Astronomy Magazine

Extensive valley network on Mars adds to evidence for ancient Martian ocean

2009-11-25T00:55:00.001-08:00

In a new study, scientists from Northern Illinois University and the Lunar and Planetary Institute in Houston used an innovative computer program to produce a new and more detailed global map of the valley networks on Mars. The findings indicate the networks are more than twice as extensive (2.3 times longer in total length) as had been previously depicted in the only other planet-wide map of the valleys.

Further, regions that are most densely dissected by the valley networks roughly form a belt around the planet between the equator and mid-southern latitudes, consistent with a past climate scenario that included precipitation and the presence of an ocean covering a large portion of Mars' northern hemisphere.

Scientists have previously hypothesized that a single ocean existed on ancient Mars, but the issue has been hotly debated.

"All the evidence gathered by analyzing the valley network on the new map points to a particular climate scenario on early Mars," NIU Geography Professor Wei Luo said. "It would have included rainfall and the existence of an ocean covering most of the northern hemisphere, or about one-third of the planet's surface."

Luo and Tomasz Stepinski, a staff scientist at the Lunar and Planetary Institute, publish their findings in the current issue of the Journal of Geophysical Research -- Planets.

"The presence of more valleys indicates that it most likely rained on ancient Mars, while the global pattern showing this belt of valleys could be explained if there was a big northern ocean," Stepinski said.

Valley networks on Mars exhibit some resemblance to river systems on Earth, suggesting the Red Planet was once warmer and wetter than present.

But, since the networks were discovered in 1971 by the Mariner 9 spacecraft, scientists have debated whether they were created by erosion from surface water, which would point to a climate with rainfall, or through a process of erosion known as groundwater sapping. Groundwater sapping can occur in cold, dry conditions.

The large disparity between river-network densities on Mars and Earth had provided a major argument against the idea that runoff erosion formed the valley networks. But the new mapping study reduces the disparity, indicating some regions of Mars had valley network densities more comparable to those found on Earth.

"It is now difficult to argue against runoff erosion as the major mechanism of Martian valley network formation," Luo said.

"When you look at the entire planet, the density of valley dissection on Mars is significantly lower than on Earth," he said. "However, the most densely dissected regions of Mars have densities comparable to terrestrial values.

"The relatively high values over extended regions indicate the valleys originated by means of precipitation-fed runoff erosion -- the same process that is responsible for formation of the bulk of valleys on our planet," he added.

The researchers created an updated planet-wide map of the valley networks by using a computer algorithm that parses topographic data from NASA satellites and recognizes valleys by their U-shaped topographic signature. The computer-generated map was visually inspected and edited with help from NIU graduate students Yi Qi and Bartosz Grudzinski to produce the final updated map.

"The only other global map of the valley networks was produced in the 1990s by looking at images and drawing on top of them, so it was fairly incomplete and it was not correctly registered with current datum," Stepinski said. "Our map was created semi-automatically, with the computer algorithm working from topographical data to extract the valley networks. It is more complete, and shows many more valley networks."

Stepinski developed the algorithms used in the mapping.

"The basic idea behind our method is to flag landforms having a U-shaped structure that is characteristic of the valleys," Stepinski added. "The valleys are mapped only where they are seen by the algorithm."

The Martian surface is characterized by lowlands located mostly in the northern hemisphere and highlands located mostly in the southern hemisphere. Given this topography, water would accumulate in the northern hemisphere, where surface elevations are lower than the rest of the planet, thus forming an ocean, the researchers said.

"Such a single-ocean planet would have an arid continental-type climate over most of its land surfaces," Luo said.

The northern-ocean scenario meshes with a number of other characteristics of the valley networks.

"A single ocean in the northern hemisphere would explain why there is a southern limit to the presence of valley networks," Luo added. "The southernmost regions of Mars, located farthest from the water reservoir, would get little rainfall and would develop no valleys. This would also explain why the valleys become shallower as you go from north to south, which is the case.

"Rain would be mostly restricted to the area over the ocean and to the land surfaces in the immediate vicinity, which correlates with the belt-like pattern of valley dissection seen in our new map," Luo said.

The research was funded by NASA.

New simulation gives Jupiter double-sized core

2008-12-21T04:07:00.001-08:00

New computer simulations, conducted at the scale of individual atoms, say Jupiter has a rocky core surrounded by ice that is more than twice as large as previously thought.

“We performed computer simulations of hydrogen-helium mixtures at high pressure and temperature conditions that occur inside Jupiter. Laboratory experiment cannot reach those extreme pressures yet,” says Professor Burkhard Militzer of the University of California, Berkeley, who calculated the properties of hydrogen and helium for temperature, density and pressure at the surface all the way to the planet's centre. Combined with known data for the planet’s mass, radius, surface temperature, gravity and equatorial bulge, co-author William Hubbard of the University of Arizona's Lunar and Planetary Laboratory used the theoretical data to build a new model for Jupiter's interior.

According to new simulations, Jupiter's core is twice as massive as originally believed. Image: NASA/R.J.Hall.

The new model suggests that Jupiter's core is an Earthlike rock 14 to 18 times the mass of Earth, equivalent to about one-twentieth of Jupiter's total mass, and with a metallic ball or iron and nickel at the centre. Previous models predicted a much smaller core of only seven Earth masses, or no core at all. The simulations also suggest that the core is made of layers of metals, rocks and ices of methane, ammonia and water, while above it is an atmosphere of mostly hydrogen and helium.

"Our simulations show there is a big rocky object in the centre
surrounded by an ice layer and hardly any ice elsewhere in the
planet,"says Militzer. "This is a very different result for the
interior structure of Jupiter than other recent models, which predict a relatively small or hardly any core and a mixture of ices throughout the atmosphere."

Militzer explains that hydrogen gradually changes from a molecular fluid in the outer layers to a metallic fluid in the deeper interior, which offers good electrical conductivity and gives rise to Jupiter's magnetic field. The homogeneous mantle is the key difference compared with older models that assume a different composition in the molecular and the metallic layers, giving rise to a smaller core.

"Our simulations show no evidence of any sharp phase transition, which led us to conclude that Jupiter's mantle is homogeneous in composition," he tells Astronomy Now. "The uncertainties in the previous models are why and where is there sharp transition and how does this change the chemical composition. No satisfactory explanation has been given, however, this is subject to further research. Our model is simpler because we assume the mantle is homogeneous since it does not make an assumption about a phase change."

Juno will reach Jupiter in 2016 and will make measurements of Jupiter's core. Image: NASA/Juno.

The results are bringing Jupiter's interior in line with that of Saturn, with a Neptune or Uranus at the centre. Neptune and Uranus are known as ice giants because they also appear to have a rocky core surrounded by icy hydrogen and helium, but without the giant gas envelopes of Jupiter and Saturn. The new Jupiter has ices that are concentrated in the outer layer of the core, while only a small amount, around one percent, is mixed in the hydrogen-helium gas envelope that contains 95 percent of the planet's mass.

The new model strongly supports the idea that Jupiter and other gas planets formed through the collision of small rocks that accreted to make a core, capturing a huge atmosphere of hydrogen and helium through its new-found gravitational attraction. "According to the core accretion model, as the original planetary nebula cooled, planetesimals collided and stuck together in a runaway effect that formed planet cores," says Militzer. "If true, this implies that the planets have large cores, which is what the simulation predicts. It is more difficult to make a planet with a small core."

In order to match the observed gravity of Jupiter, Militzer's
simulation also predicts that different parts of Jupiter's interior rotate at different rates. Jupiter can be thought of as a series of concentric cylinders rotating around the planet's spin axis, with the outer cylinders - the equatorial regions - rotating faster than the inner cylinders, in a similar fashion to how the Sun rotates. Future data from NASA's Juno mission, to be launched in 2011 and reaching Jupiter by 2016, will measure the planet's magnetic field and gravity, and provide a check on Militzer and Hubbard’s predictions.

The team also plan to use the new model to simulate other planets' interiors, and to investigate the implications for the formation of planets outside our Solar System

from:astronomynow.com

Buried ice found at low latitudes on Mars

2008-12-21T04:07:00.000-08:00

NASA's Mars Reconnaissance Orbiter has revealed vast Martian glaciers of water ice buried under protective blankets of rocky debris at much lower latitudes than any ice previously identified on the Red Planet.

Using the spacecraft’s ground-penetrating radar instrument, which can see up to one kilometre below the surface of the planet, scientists have discovered that buried glaciers extend laterally for dozens of kilometres from the edges of mountains or cliffs in the Hellas Basin region of Mars' southern hemisphere.

Artist impression of an exposed glacier on Mars. Image: NASA/JPL.

"Altogether, these glaciers almost certainly represent the largest
reservoir of water ice on Mars that is not in the polar caps," says John Holt of the University of Texas at Austin, and lead author of the report that appears in the 21 November issue of the journal Science. "Just one of the features we examined is three times larger than the city of Los Angeles and up to half a mile thick. And there are many more. In addition to their scientific value, they could be a source of water to support future exploration of Mars."

Scientists have long been puzzled by the appearance of features known as ‘aprons’, gently sloping areas containing rocky deposits at the bases of taller geographical features, since NASA's Viking orbiters first observed them on the Martian surface in the 1970s. One theory has been that the aprons are flows of rocky debris lubricated by a small amount ice. The Mars Reconnaissance Orbiter has finally provided scientists with an answer to this long-lived mystery.

"These results are the smoking gun pointing to the presence of large amounts of water ice at these latitudes," says Ali Safaeinili, a shallow radar instruments team member with NASA's Jet Propulsion Laboratory. Radar waves are sensitive to changes in the electrical reflection characteristics of rock, sand or water. Water returns a particularly strong signal, and the latest measurements report that the radio waves pass straight through the aprons and reflect off a deeper surface below, without significant loss in strength. The readings imply that the aprons are composed of thick ice under a relatively thin covering of rock, and rule out the presence of a significant amount of rocky debris within the ice.

A large portion of a debris apron along the bottom of a hill on Mars. Scientists have long suspected that ice may be involved with ‘softening’ the appearance of these features, and radar has now revealed them to be hiding vast reservoirs of ice beneath a rocky surface. Image: NASA/JPL/University of Arizona.

It is now a priority to observe other examples of these aprons seen in different areas of Mars to determine whether they are also hiding ice. "There's an even larger volume of water ice in the northern deposits," says JPL geologist Jeffrey Plaut. "The fact these features are in the same latitude bands, about 35 to 60 degrees in both hemispheres, points to a climate-driven mechanism for explaining how they got there."

It is likely that the ice sheets were laid down during a previous ice age on Mars, and scientists suspect that the rocky debris blanket topping the glaciers has protected the ice from vapourising, which would happen if it were exposed to the atmosphere at these latitudes. The discovery is similar to massive ice glaciers that have been detected under rocky coverings in Antarctica.

"The tilt of Mars' spin axis sometimes gets much greater than it is now,” says James W Head of Brown University. “Climate modelling tells us ice sheets could cover mid-latitude regions of Mars during those high-tilt periods. The buried glaciers make sense as preserved fragments from an ice age millions of years ago.”

On Earth, buried glacial ice in Antarctica preserves the record of traces of ancient organisms and past climate history. Who knows what secrets the buried Martian glaciers are keeping.

from:astronomynow.com

A localised cosmic ray influx

2008-12-21T04:01:00.001-08:00

Research conducted at the Milagro observatory has uncovered two nearby regions in space that exhibit unusually high readings of cosmic rays.

This is the second finding of a source of near-Earth galactic cosmic rays announced in the past week; scientists working on the ATIC experiment reported a surplus of cosmic ray electrons near to the Earth in the 20 November issue of the journal Nature. You can read our report here.

"These two results may be due to the same, or different, astrophysical phenomenon,” says Jordan Goodman of the University of Maryland and principal investigator for Milagro. "However, they both suggest the presence of high-energy particle acceleration in the vicinity of the Earth. Our new findings point to general locations for the localised excesses of cosmic-ray protons observed with the Milagro observatory."

Showers of high energy particles occur when high energy particles strike the top of the atmosphere. Image: Simon Swardy/U. Chicago/ NASA.

Cosmic rays are charged particles, including protons and
electrons, that are accelerated to high energies from sources both outside and inside our Galaxy. It is unknown exactly what creates these cosmic rays, but likely culprits may include supernovae, quasars or even more exotic processes involving dark matter. Until recently, it was widely believed that cosmic ray particles bombarded the Earth uniformly from all directions. These new findings are the strongest indications yet that the distribution of cosmic rays is much more variable.

"Whatever the source of the protons we observed with Milagro, their path to Earth is deflected by the magnetic field of the Milky Way so that we cannot directly tell exactly where they originate," says Goodman. "And whether the regions of excess seen by Milagro actually point to a source of cosmic rays, or are the result of some other unknown nearby effect is an important question raised by our observations."

Based on seven years worth of observations of the entire sky above the northern hemisphere, and over 200 billion cosmic ray collisions with the Earth's atmosphere, the researchers could see statistical peaks in the number of cosmic ray events originating from relatively small regions of the sky. An excess of cosmic ray protons were found in an area above and to the right of Orion, near the constellation Taurus. The other hot spot was identified as comma-shaped region in the sky near the constellation Gemini.

The Milagro Observatory is located under several metres of water to enhance cosmic ray particle detections. Image: Milagro Observatory.

The Milagro observatory is located in a 60 x 80 x 8 metre covered pond in the Jemez Mountains near Los Alamos, New Mexico, and detects cosmic rays by observing the energetic secondary particles that make it to the surface. The Earth’s atmosphere protects us from direct strikes of high energy cosmic ray particles and when a high-energy cosmic ray enters the atmosphere it loses its energy via interactions with the nuclei that make up the air. These interactions create a large cascade of secondary particles in an ‘air shower’. The particles in the air shower interact much more quickly with water than air, and generate more detectable particles in water, which is why cosmic ray detectors are usually encased in water.

Future observations of cosmic rays may come in the form of a new observatory that Goodman and colleagues have proposed to the National Science Foundation. This second-generation experiment named the High Altitude Water Cherenkov experiment (HAWC) would be built at a high altitude site in Mexico.

from:astronomynow.com

More evidence for water reservoir at Enceladus

2008-12-21T04:01:00.000-08:00

Scientists have found more evidence to suggest that the geyser like plumes spewing out from Saturn’s icy moon Enceladus may be sourced from a warm liquid ocean buried deep within the moon.

Using data collected by the Cassini spacecraft's Ultraviolet Imaging Spectrograph, scientists from the Jet Propulsion Lab, the University of Colorado and the University of Central Florida see evidence for vents channelling water vapour from the liquid reservoir to the surface at supersonic speeds, supporting a mathematical model proposed last year.

Are Enceladus' jets sourced by a warm liquid water ocean buried deep within the icy moon? The debate continues. Image: NASA/JPL/Space Science Institute.

"There are only three places in the Solar System we know or suspect to have liquid water near the surface," says Professor Joshua Colwell of the University of Central Florida. "Earth, Jupiter's moon Europa and now Saturn's Enceladus. Water is a basic ingredient for life, and there are certainly implications there. If we find that the tidal heating that we believe causes these geysers is a common planetary systems phenomenon, then it gets really interesting."

On Earth, liquid water exists four kilometres below ice at Lake Vostok and in some 140 other shallower lakes in Antarctica, so the possibility of similar reservoirs on other planetary bodies is not out of the question. Indeed, many groups of scientists working on Cassini data suspect that a liquid ocean is a strong possibility for Europa.

One recent theory proposes that the jets could be violent bursts of volatile ices that suddenly become exposed to space when Saturn’s tidal forces open and close the tiger stripes at Enceladus’ south pole. The new results, however, cast doubt on this idea. Instead the team found more water vapour coming from the vents at times when the theory predicted there should have been less. That is, at times when Enceladus is further away from Saturn, the vents would compress, reducing or shutting off the jets completely.

"Our observations do not agree with the predicted timing of the
faults opening and closing due to tidal tension and compression," says Candice Hansen, the lead author on the project. "We don't rule it out entirely, but we also definitely do not substantiate this hypothesis."

By observing the flickering light of a star as the geysers impaired a direct view of it on two occasions in 2005 and 2007, the team made measurements of the water vapour content and density of the jets. Theory predicted that more water vapour would be recorded in 2005 when the vents were open than in 2007 when they were closed. But Hansen and colleagues found that the 2007 plume was twice as dense as in 2005, the direct opposite of the original prediction. Their results are presented in the 27 November issue of the journal Nature.

Hansen’s work supports an earlier idea that the vents are like nozzles, focussing the water vapour from depth to the surface at supersonic speeds. They propose that ice grains would condense from the vapour and stream through the cracks in the ice crust before heading into space. The team conclude that only high temperatures close to the melting point of water ice could account for the high speed of the water vapour jets.

Whether there is liquid water present still remains uncertain, but if conclusive evidence arises there would be strong implications for Enceladus as a potential environment to support life. Enceladus will remain a high priority target throughout Cassini’s extended Equinox Mission, which will continue until September 2010.

from:astronomynow.com

Milky Way’s mammoth stars resolved by Hubble

2008-12-21T03:59:00.000-08:00

Two of our Galaxy's most massive stars have been scrutinised by the Hubble Space Telescope to reveal a third component of the system.

The pair of mammoth stars, WR 25 and Tr16-244, are located within the open cluster Trumpler 16, which itself is embedded within the Carina Nebula around 7,500 light years from Earth. Many stars in the Carina Nebula, including the highest luminosity star known, Eta Carinae, are ultra bright, hot stars, emitting most of their radiation in the ultraviolet and appearing blue in colour. They burn so ferociously that they power through their hydrogen fuel source faster than any other type of star.

WR 25 is situated near the centre of the image in the bottom third. Tr16-244 is located to the upper left of WR 25. The star to the left of WR 25 is a low mass star located much closer to the Earth. The massive stars are thought to be responsible for the radiation that is creating a giant gas bubble, and controlling the globule's interesting shape, which includes a finger-like shape pointing towards WR 25 and Tr16-244. Image: NASA, ESA, and J. Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain).

WR 25 and Tr16-244 interest astronomers because they are associated with star-forming nebulae, and influence the structure and evolution of galaxies. Such massive stars are usually formed in compact clusters, and combined with their extreme brightness, makes the study of any individual star very difficult. New Hubble observations have come to the rescue. Obtained by a team of scientists from US, Chilean, Spanish, and Argentine institutions and led by Jesus Maiz Apellaniz from the Instituto de Astrofisica de Andalucia in Spain, astronomers have been given an even finer look at the system, revealing that the pair is actually a triple star system. The third star takes tens or even hundreds of thousands of years to orbit the other two stars.

The true nature of WR 25 was revealed two years ago when astronomers discovered that it was actually composed of two stars. WR 25 is the more massive Wolf-Rayet star and may weigh more than 50 times the mass of our Sun. It is losing mass rapidly through powerful stellar winds that have ejected the majority of its outermost hydrogen-rich shells, while its more commonplace binary companion is roughly half as massive, orbiting around it once every 208 days.

Two of the stars are so close to each other that they look like a single object, but Hubble's Advanced Camera for Surveys reveals them as two. Image: NASA, ESA, and J. Maíz Apellániz (Instituto de Astrofísica de Andalucía, Spain).

Astronomers believe that WR 25 and Tr16-244 are the likely sources of radiation that is causing a giant gas globule within the Carina Nebula to slowly evaporate away into space, while possibly inducing the formation of new stars within it.

The research team are using Hubble as well as ground-based observatories in Spain, Chile, and Argentina to build a comprehensive catalogue of observations of all the massive stars in the Galaxy that are detectable at visible wavelengths.

from:Astronomynow.com

Nature of ‘Hanny's Voorwerp’ revealed

2008-12-21T03:58:00.000-08:00

Radio observations of a curious feature brought to the attention of astronomers by Dutch Galaxy Zoo volunteer Hanny van Arkel have finally revealed the nature of the object that came to be known as Hanny’s Voorwerp.

Like many ordinary Galaxy Zoo volunteers, Hanny was surfing through hundreds of galaxy images when she stumbled across a huge green irregular cloud of gas located about 60,000 light years from a nearby galaxy, IC 2497. Nicknamed Hanny’s Voorwerp (Dutch for object), its nature and origin have had astronomers scratching their heads for over a year.

The green gas cloud bears temperatures of over 15,000 degrees Celsius, but curiously, it is devoid of stars. Using the Westerbork Synthesis Radio Telescope (WSRT) and an e-VLBI array, an international team of astronomers led by Professor Mike Garrett of the Netherlands Institute for Radio Astronomy (ASTRON), and including Hanny van Arkel herself, have observed IC 2497 and the Voorwerp, to dig deeper into the mystery.

WSRT observations reveal a radio jet (white contours) emanating from the centre of the nearby galaxy IC 2497, headed straight in the direction of Hanny's Voorwerp (green). The observations also reveal a huge reservoir of hydrogen gas (coloured orange) that probably arose from a previous encounter between IC2497 and another galaxy. The presence of strong neutral hydrogen absorption (top right plot) argues that the central regions of IC2497 are highly obscured. Image: ASTRON/Dan Herbert/Isaac Newton Telescope.

The observations reveal a jet of highly energetic particles that are being generated by none other than a massive black hole lurking at the centre of the neighbouring galaxy. "It looks as though the jet emanating from the black hole clears a path through the dense interstellar medium of IC 2497 towards Hanny's Voorwerp", says Garrett. "This cleared channel permits the beam of intense optical and ultraviolet emission associated with the black hole to illuminate a small part of a large gas cloud that partially surrounds the galaxy. The optical and ultraviolet emission heats and ionises the gas cloud, thus creating the phenomena known as Hanny's Voorwerp.”

Another question that astronomers had was ‘where does all the hydrogen gas come from?’ The total mass of gas is about 5,000 million times the mass of the Sun and extends across hundreds of thousands of light years. Team member Dr Tom Oosterloo thinks that it has all the hallmarks of an interacting system. “The gas probably arises from a tidal interaction between IC 2497 and another galaxy, several hundred million years ago,” he says. "The stream of gas ends three hundred thousand light years westwards of IC2497 - all the evidence points towards a group of galaxies at the tip of the stream being responsible for this freak cosmic accident".

Hanny van Arkel shares the excitement of the professional team of astronomers, and visited ASTRON to find out more about the object she stumbled upon. "I'm happy we are making progress,” she says. “Apparently the more we learn about the Voorwerp, the more intriguing it becomes".

The team still think that the Voorwerp has a few more secrets to reveal, and plan much deeper observations with the WSRT and other higher resolution radio telescopes soon.

from:Astronomynow.com

Galaxy evolution: nature or nurture?

2008-12-21T03:54:00.000-08:00

UK astronomers working on data from two separate projects - Galaxy Zoo and the Space Telescope A901/902 Galaxy Evolution Survey (STAGES) - have both uncovered a type of galaxy that represents a missing link in galaxy evolution.

Astronomers broadly divide galaxies into two categories according to their shape: either disc-like systems like our own Milky Way which exhibits spiral arms, or round, rugby-ball shaped collections of stars known as ellipticals. In most cases, a galaxy's shape matches its colour: spiral galaxies appear blue because they are still vigorously forming hot young stars, while elliptical galaxies are mostly old, dead and red, and tend to cluster together in crowded regions of space.

But new results, based on two independent studies, reveal a population of unusual spiral galaxies that appear red. "In order to have spiral arms, they must have been normal, blue, spiral galaxies up until fairly recently,” says Dr Steven Bamford of the University of Nottingham who led the Galaxy Zoo study. “But for some reason their star formation has been stopped, and they have turned red. Whatever caused them to stop forming stars can't have been particularly violent, or it would have destroyed the delicate spiral pattern."

These images of three galaxies from the Galaxy Zoo (top) and STAGES surveys (bottom) show examples of how the newly discovered population of red spiral galaxies on the outskirts of crowded regions in the Universe may be a missing link in our understanding of galaxy evolution. The left hand galaxies show young blue spiral galaxies and the right are examples of elliptical galaxies containing old, red stars. The central images show the new class of red spiral galaxy, thought to be changing from blue spirals into red as star formation has been shut off by interactions with the environment. Image: Hubble Space Telescope/COMBO-17 survey/Marco Barden, Christian Wolf, Meghan Gray (STAGES) & Sloan Digital Sky Survey (Galaxy Zoo).

While Galaxy Zoo looked at the gross properties of millions of
galaxies across a large area of sky, the STAGES project examined in detail the types of neighbourhood where transformations between the two types of galaxies are expected to occur, such as the A901/902 supercluster of spiral galaxies. Using the Hubble and Spitzer Space Telescopes, the STAGES team uncovered a surprisingly large population of red spiral galaxies.

"For the STAGES galaxies, the Spitzer Space Telescope provided us with additional images at infrared wavelengths,” says STAGES scientist Dr Christian Wolf of the University of Oxford. “With them, we were able to go further and peer through the dust to find the missing piece of the puzzle". Wolf discovered that the red spirals were hiding low levels of hidden star formation, despite their otherwise lifeless appearance in visible light.

Astronomers have used the complementary observations to come up with a new theory of how nature and nurture have both played a significant role in these galaxies’ evolution. They suggest that star formation in blue spiral galaxies is gradually shut off and hidden behind dust, before slowly smoothing out to form lens-shaped red galaxies with no trace of spiral arms. To directly transform the galaxy into an elliptical would require collisions of galaxies.

The local environment of the galaxy also turns out to be important in determining when and how quickly its star formation is shut down. The red spirals are found primarily on the outskirts of crowded regions of space where galaxies cluster together. As a blue galaxy is drawn into the cluster by gravity, an interaction with its environment causes a slow-down in star formation. The astronomers see that the further in a galaxy is, the more it is affected by its environment.

The Abell 901/902 supercluster as seen by COMBO-17 in the STAGES survey. This complex system provides an ideal laboratory for studying the links between environment and galaxy evolution. Image: STAGES/COMBO-17/HST.

But if environment decides where the process occurs, the two teams also found that the mass of the galaxy decides how quickly it takes place. "Just as a heavyweight fighter can withstand a blow that would bring a normal person to his knees; a big galaxy is more resistant to being messed around by its local environment,” explains Galaxy Zoo team member Professor Bob Nichol of Portsmouth University. “Therefore, the red spirals that we see tend to be the larger galaxies - presumably because the smaller ones are transformed more quickly."

The next step for both teams is to find out exactly what shuts off the star formation, by looking inside the galaxies themselves. One suspect behind the slow demise of galaxies is a process known as strangulation, in which a galaxy's fuel supply is stripped away as it encounters a crowd of galaxies. Starved of the raw material needed to form new stars, it will slowly change colour from blue to red as its existing stars age.

"These results are possible thanks to a major scientific
contribution from our many volunteer armchair astronomers,” says Galaxy Zoo team leader Chris Lintott. “No group of professionals could have classified this many galaxies alone.”

The original Galaxy Zoo launched in the summer of 2007 and saw over 150,000 visitors classify one million galaxies, resulting in enough data to fill some six scientific papers. Galaxy Zoo 2 is currently being prepared to answer more detailed questions about the morphologies of around 250,000 galaxies from the original survey in order to compile the most comprehensive data set of galaxy shapes yet.

from:http://astronomynow.com/081126galaxyevolutionnatureornurture.html

Chandrayaan-1 Moon probe a big hit

2008-12-21T03:52:00.000-08:00

India’s first mission to the Moon, Chandrayaan-1, has begun making science observations and successfully deployed its Moon Impact Probe at the lunar south pole.

The 29 kilogram Moon Impact Probe (MIP) was dropped close to Shackleton crater, where ice is thought to exist in areas that are permanently in shadow. The probe carried three instruments: a video imaging system, a radar altimeter and a mass spectrometer, which took images, determined altitude and studied the thin lunar atmosphere during the 25 minute descent, respectively. The data was transmitted back to the orbiter and later downloaded to Earth.

Two raw images of the lunar surface taken by the camera on the Moon Impact Probe after separating from Chandrayaan-1. Image: ISRO.

The probe struck the lunar surface at a velocity of 1.5 kilometres per second. “The precise point where the MIP went down is still being analysed,” says Detlef Koschny, Chandrayaan-1 project scientist for ESA. “It was not controlled and the intention was simply to get it down in the area of the South Pole, not to go inside of Shackleton.”

The main goal of the MIP was a technology demonstration to show that scientific analysis could be performed during the probe’s descent, and the science team are currently putting together the data for public consumption. The impact speed in this case was too low to throw up any dust or ice but that is one of the goals of NASA’s upcoming LCROSS mission that should excavate material from one of the Moon’s dark south pole craters, and will finally confirm the presence or absence of water ice there. The identification of water is very important to the future of human activities on the Moon.

The rest of Chandrayaan-1’s instruments are now beginning science operations, once completing a commissioning phase. That is, all the standard modes of each instrument are tested by carrying out routine ‘housekeeping’ activities to verify that everything is working properly. The European Space Agency is involved with three instruments - C1XS (Chandrayaan-1 X-ray Spectrometer), SARA (Sub-keV Atom Reflecting Analyser) and SIR-2 (a near-infrared spectrometer), of which SIR-2 has already begun science observations, C1XS is performing routine tests and SARA will be commissioned in the coming weeks. “Full science operations will begin mid-December, of course pending successful instrument commissioning,” says Koschny.

C1XS, SARA and SIR-2 will all map the Moon’s composition in different ways. C1XS, built by UK scientists and engineers, will quantify the Moon’s mineral resources and is expected to unearth clues regarding the origin of the Earth-Moon system. SARA will investigate the space environment around the Moon, and the interactions of the solar wind with the Moon's surface. SIR-2 will survey the Moon's mineral composition and the effect of space weathering, since in the absence of an atmosphere the Moon’s barren surface is exposed directly to the harsh environment of space. Accurate maps of the Moon’s surface composition will help planetary scientist unravel the Moon’s geological history, which will help us better understand the origin of the Earth-Moon system. The results are also expected to teach us more about what happened on the Moon since it formed and how and when it cooled.

from:http://astronomynow.com/081125Chandrayaan1Moonprobeabighit.html

First map of Mars’ aurorae

2008-12-21T03:50:00.001-08:00

Scientists using ESA's Mars Express have produced the first crude map of aurorae on Mars.

The aurorae on Mars were first discovered in 2004 using the SPICAM ultraviolet and infrared atmospheric spectrometer onboard Mars Express, which revealed displays of ultraviolet light associated with the residual magnetic fields generated by Mars' crustal rocks. Now, using coordinated observations from SPICAM, the MARSIS sub-surface sounding radar altimeter's radar, and the energetic neutral atoms analyser ASPERA, Francois Leblanc from the Service d'Aeronomie and colleagues have observed nine new auroral emission events, which have allowed them to make the first crude map of auroral activity on Mars.

Artist impression of how the 'green' aurorae may look to an observer orbiting on the night-side of Mars. Image: M. Holmström (IRF).

The observations show that the aurorae seem to be located near regions where the Martian magnetic field is the strongest, confirming earlier MARSIS detections of higher-than-expected electrons in similar regions. This tentatively suggests that the magnetic fields help to create the aurorae, but there is still a lot of work to do in determining how they arise, since Mars lacks the same large scale internal mechanism that drives the magnetic fields on other planets. Instead, it just generates small pockets of magnetism where areas of rocks in the crust of Mars are themselves already magnetic, resulting in many magnetic pole-type regions all over Mars.

On Earth, aurorae are usually confined to the polar regions and shine brightly in visible light as well as at ultraviolet wavelengths. The existence of similar aurorae is also well known on the giant planets of the Solar System and occur wherever a planet's magnetic field channels electrically charged particles blown out from the Sun in the solar wind into the planet’s atmosphere. But how the electrons are accelerated to sufficiently high energies to spark aurorae on Mars remains a mystery. "It may be that magnetic fields on Mars connect with the solar wind, providing a road for the electrons to travel along," says Leblanc.

Terrestrial aurorae are displayed typically in reds and greens, as a result of the interaction of molecular and atomic oxygen and molecular nitrogen in the atmosphere with the solar wind particles. These molecules are not abundant enough in the Martian atmosphere and so it is uncertain if similar light shows would be observed from the red planet’s surface. Furthermore, SPICAM is designed to work at ultraviolet wavelengths and cannot see whether visible light is being emitted as well. But the new results will provide plenty of work for the scientists in the months and years to come, and will offer new insight to the composition and structure of the Martian atmosphere and how the planet interacts with electrically charged particles originating from the Sun.

"There's now a large domain of physics that we have to explore in order to understand the aurorae on Mars,” says Leblanc. “Thanks to Mars Express we have a lot of very good measurements to work with."

from:http://astronomynow.com/081124FirstmapofMarsaurorae.html

Beta Pictoris planet finally imaged?

2008-12-21T03:50:00.000-08:00

Inside the debris disc of Beta Pictoris lies a newly discovered object. If confirmed as a gas giant, it will be the first image of a planet that is as close to its host star as Saturn is to the Sun.

The hot star Beta Pictoris is one of the best known examples of stars surrounded by a debris disc – the dusty remains of past collisions among planetary building blocks and asteroids. Previous observations of the system revealed a peculiar shape to the disc, a secondary inclined disc, and comets tumbling towards the central star. With a projected distance from the star of only eight times the Earth-Sun distance, the new object discovered by a team of French astronomers using ESO's Very Large Telescope is most likely a giant planet that astronomers suspected might be lurking there all along.

"These are indirect, but tell-tale signs that strongly suggest the presence of a massive planet lying between five and ten times the mean Earth-Sun distance from its host star," says team leader Anne-Marie Lagrange. "However, probing the very inner region of the disc, so close to the glowing star, is a most challenging task."

This composite image represents the close environment of Beta Pictoris as seen in near infrared light. The newly detected source is more than 1000 times fainter than Beta Pictoris, aligned with the disc, at a projected distance of eight times the Earth-Sun distance. Image: ESO/A.-M. Lagrange et al.

The team imaged the Beta Pictoris system around five years ago using the NAOS-CONICA instrument (NACO) mounted on one of the 8.2 metre units of the Very Large Telescope (VLT). Recently, a member of the team re-analysed the data in infrared to seek the trace of a companion to the star. "For this, the real challenge is to identify and subtract as accurately as possible the bright stellar halo," explains Lagrange. "We were able to achieve this after a precise and drastic selection of the best images recorded during our observations."

A feeble, point-like glow well inside the star's halo was discerned, with independent analysis throwing up the same result: the companion is real. "Our observations point to the presence of a giant planet, about eight times as massive as Jupiter and with a projected distance from its star of about eight times the Earth-Sun distance, which is about the distance of Saturn in our Solar System," says Lagrange.

However, the team cannot yet rule out the possibility that the candidate companion could be a foreground or background object, and so the team will have to make some more observations to confirm the nature of the discovery, although the fact that the object lies in the plane of the star’s disc strongly implies that it is bound to the star and its proto-planetary disc. "Moreover, the candidate companion has exactly the mass and distance from its host star needed to explain all the disc's properties. This is clearly another nail in the coffin of the false alarm hypothesis," adds Lagrange.

Once confirmed, this candidate companion will be the closest planet from its star ever imaged directly, although planets have been inferred orbiting closer to their host stars in other studies using different methods. By studying different planetary systems, scientists can learn about the different formation processes of planets at varying distances from their host stars.

"Direct imaging of extrasolar planets is necessary to test the various models of formation and evolution of planetary systems. But such observations are only beginning,” says team member Daniel Rouan. “Limited today to giant planets around young stars, they will in the future extend to the detection of cooler and older planets, with the forthcoming instruments on the VLT and on the next generation of optical telescopes."

Beta Pictoris is 12 million years old and located about 70 light years away from Earth towards the constellation Pictor.

from:http://astronomynow.com/081124BetaPictorisplanetfinallyimaged.html

Hubble resolves mystery of lone starburst galaxy

2008-12-21T03:47:00.000-08:00

Astronomers have solved the mystery as to why a small, nearby, isolated galaxy is pumping out new stars faster than any galaxy in our local neighborhood. It turns out it is actually further away than astronomers first thought.

The discovery happened by accident while Alessandra Aloisi and colleagues from the Space Telescope Science Institute in Baltimore and the European Space Agency were using Hubble to search galaxy NGC 1569 for red giant stars. Red giants can be used to estimate a galaxy's age since they are reliable ‘standard candles’ for measuring distance because they all shine at the same brightness.

"When we found no obvious trace of them, we suspected that the galaxy was farther away than originally believed," says Aaron Grocholski. "We could only see the brightest red giant stars, but we were able to use these stars to re-calibrate the galaxy's distance."

NGC 1569's core is made up of three giant star clusters, each containing more than a million stars. New analysis place the galaxy at a distance of 11 million light years from Earth. Image: NASA/ESA/STScI/AURA/Hubble Heritage Team/A.Aloisi.

Previous estimates of the galaxy's distance were made with ground-based telescopes and were unreliable because they looked at the galaxy's crowded core and were unable to resolve individual red giant stars. Hubble was able to resolve both the galaxy's cluttered core and its sparsely populated outer fringes, identifying individual red giants, and therefore allowing a precise distance to the galaxy to be determined.

"This was a serendipitous discovery," says Aloisi. "Hubble didn't go deep enough to see the faintest red giant stars we were hunting for because the galaxy is farther away than we thought. However, by capturing the entire population of the brightest red giant stars, we were able to calculate a precise distance to NGC 1569 and resolve the puzzle about the galaxy's extreme starburst activity."

The new observations reveal that it is located around one and a half times farther away than astronomers previously thought, at a distance of nearly 11 million light years. The extra distance places the galaxy in the middle of a group of about 10 galaxies centred on the spiral galaxy IC 342. Gravitational interactions among the group's galaxies may be compressing gas in NGC 1569 and igniting the frenetic bout of star formation, which is over 100 times higher than star formation in the Milky Way.

"Now the starburst activity seen in NGC 1569 makes sense, because the galaxy is probably interacting with other galaxies in the group," says Aloisi. "Those interactions are probably fueling the star birth."

This type of starburst galaxy is thought to drive the evolution of galaxies in the distant and young Universe. "Starburst galaxies can only be studied in detail in the nearby Universe, where they are much rarer,” says Roeland van der Marel. “Hubble observations of our galactic neighborhood, including this study, are helping astronomers put together a complete picture of the galaxies in our local Universe. Put the puzzle pieces in the right place, as for NGC 1569, and the picture makes much more sense."

The results are published in the 20th October issue of the journal Astrophysical Journal Letters.

from:http://astronomynow.com/081121Hubbleresolvesmysteryoflonestarburstgalaxy.html

Mysterious source of high energy cosmic rays

2008-12-21T03:45:00.000-08:00

The NASA-funded Advanced Thin Ionization Calorimeter (ATIC) balloon instrument has discovered a previously unidentified nearby source of high energy cosmic rays.

The 1,950 kilogram ATIC experiment was designed to be carried to an altitude of about 37,800 metres above Antarctica using a helium-filled balloon. The goal was to study cosmic rays – energetic particles originating from objects in space – that otherwise would be absorbed into the Earth’s atmosphere. Published in this week’s issue of the journal Nature, new results show an unexpected surplus of cosmic ray electrons at very high energy – 300-800 billion electron volts – that must come from a previously unidentified source or from the annihilation of very exotic theoretical particles used to explain dark matter.

"This electron excess cannot be explained by the standard model of cosmic ray origin," says John Wefel, ATIC project principal investigator. "There must be another source relatively near us that is producing these additional particles."

The crew from the Columbia Scientific Balloon Facility prepares to launch the Advanced Thin Ionization Calorimeter (ATIC) experiment from McMurdo Station, Antarctica. Image: NASA.

According to the research, this source would need to be within about 3,000 light years of the Sun. But because of their nature, charged particles are deflected in the galactic magnetic field between wherever they originate and when they are detected at the Earth. "While we do measure the arrival direction, it is not connected to the source location because of bending and scattering in the magnetic field," Wefel tells Astronomy Now.

The source of the cosmic rays could be an exotic object such as a pulsar, mini-quasar, supernova remnant or an intermediate mass black hole. "There are new objects and sources being discovered every day and week," says Wefel. "The ones we know about now do not seem to be able to do the job, but maybe next month one will be found to explain our excess electron data. But since we do not yet see such a source, maybe the alternate explanation – dark matter annihilation – should be considered."

Dark matter is thought to comprise around 23 percent of the Universe’s energy density, while ‘normal’ matter comprises just four percent. Dark energy, which is thought to play a dominant role in the expansion of the Universe, makes up 73 percent. The nature of dark matter is not understood, but its presence can be inferred from the gravitational effects it imposes on visible matter, such as distorting galaxy structure and influencing their rotation speeds. Several theories that describe how gravity works at very small, quantum distances predict exotic particles that could be good dark matter candidates.

"The annihilation of these exotic particles with each other would produce normal particles such as electrons, positrons, protons and antiprotons that can be observed by scientists," says Eun-Suk Seo, ATIC lead at the University of Maryland. "These results may be the first indication of a very interesting object near our Solar System waiting to be studied by other instruments," adds Wefel.

The science team are hoping that there will be new and continuing searches to try to locate a nearby source that can explain the data. "But, we also need to study the exact shape of this feature in more detail to see if it really does have the tell-tale shape expected for dark matter annihilation. That is the on-going experimental challenge," says Wefel.

from:http://astronomynow.com/081121Mysterioussourceofhighenergycosmicrays.html

Planet found orbiting dangerously close to red giant

2008-12-21T03:43:00.000-08:00

A new planet found orbiting a red giant star at a distance of just 0.6 AU may shed new light on how aging stars influence nearby planets before they are consumed.

The new exoplanet is around six times the mass of Jupiter and orbits its dying star – HD 102272 – at a distance closer than Venus is to our Sun. The discovery was made by a team of astronomers from Penn State and Nicolaus Copernicus University in Poland using the Hobby-Eberly Telescope of McDonald Observatory in southwestern Texas. By using the telescope’s spectrograph, the astronomers observed patterns in the spectral lines of the light radiating from HD 102272 that represent the fingerprint of a star that is moving alternately toward and away from Earth as it wobbles in space in response to the gravitational pull of an orbiting planet. The specific pattern of these shifts allowed the scientists to determine that at least one planet, and possibly even two, orbit the star. If the second planet exists, the system would become the first multi-planet system discovered around a red giant star.

“If real, the second planet has a very eccentric (e=0.68) orbit with a semi-major axis of 1.6 AU,” team member Professor Alexander Wolszczan tells Astronomy Now. Wolszczan is also the discoverer of the very first planets found outside our Solar System over 15 years ago.

The Hobby-Eberly telescope is located at the McDonald Observatory in far West Texas, which has the darkest skies of any major observatory in the continental United States. Image: Marty Harris/McDonald Obs./UT-Austin.

The team hope that the intriguing system will shed light on the ways in which aging stars can influence nearby planets, although it is already well known that stars of about 0.5-8 solar masses swell and expand towards the end of their lifetimes, possibly swallowing up nearby planets. A similar fate is destined for the Earth in a few billion years time.

“The star is twice as massive as the Sun, meaning that it's been evolving much faster,” says Wolszczan. “Possibly, it will engulf the planet in less than ~100 million years, when it rapidly expands after helium ignition”. From the perilously close distance of 0.6 AU the steadily expanding giant would appear in the planets' alien skies as a huge, reddish disc that is more than 16 times larger than the face of Earth's full Moon appears to us.

“Just like with our planets, the one out there is not much younger than the star, which may currently be at, say, no more than 1.5 billion years,” says Wolszczan. “Detecting planets like that tells us about long-term survival of planetary systems around evolving stars and chances of life to cope with the process or, maybe, even start over, since habitable zones move away and expand as a red giant evolves in time.” Indeed, when our own Sun swells into a red giant, there is the possibility that Jupiter’s icy satellite Europa may fall into the sought after habitable zone. Currently shrouded by an icy shell but possibly hiding an ocean beneath, if it were to exist closer to the Sun, it might become a warm ocean world that could possibly support life.

Wolszczan and colleagues hope that the discovery will teach them about the evolution of planets orbiting extremely close to a red giant star, and what causes planets to avoid forming too close to such a monster. “Although the planet we discovered conceivably could be closer to the star without being harmed by it, there appears to be a zone of avoidance around such stars,” explains Wolszczan. “Our discovery pushes it back to about 0.6 AU, which is the size of the new planet's orbit. It is important to find out why planets don't want to get any closer to stars, so one of our next steps is to try to figure out why this zone of avoidance exists and whether it occurs around all red giant stars.”

HD 102272 is located 1,200 light-years from the Earth in the constellation Leo

from: http://astronomynow.com/081120Planetfoundorbitingdangerouslyclosetoredgiant.html

Site selection narrows for next Mars lander

2008-12-21T03:42:00.001-08:00

Four potential landing sites on Mars have been selected as candidates for the touch-down of NASA’s next roving Mars mission, the Mars Science Laboratory.

Location map of the proposed landing sites of the MSL (white labels) compared with the locations of previous Mars missions (marked in yellow). The MSL site selection has now been narrowed to Eberswalde, Holden, Gale Crater and Mawrth Vallis. Image: NASA/JPL.

Three other sites were eliminated in this round and the winning site will be announced next summer, after further evaluation of observations made by Mars orbiters have been made to assess the scientific value and safety risks of the proposed sites. In the running are locations known as Eberswalde, located in an ancient river delta and thought to contain clay minerals that might contain evidence for the carbon chemistry crucial for life; Gale crater, which sports a five kilometre high mountain of layered materials that would provide a record from environments that produced clay deposits near the bottom to later environments that produced sulfate deposits partway up; Holden crater, which bears witness to gullies carved by running water which deposited sediments and clays in lake beds; and Mawrth Valley, a flood channel on the mysterious boundary that separates the northern lowlands from the southern highlands of Mars.

"All four of these sites would be great places to use our roving
laboratory to study the processes and history of early Martian environments and whether any of these environments were capable of supporting microbial life and its preservation as biosignatures," says John Grotzinger, Mars Science Laboratory project scientist.

Several of the sites had been proposed for past missions such as the Mars Exploration Rovers (MERs) Spirit and Opportunity, but were ruled out as too hazardous for the capabilities of those rovers. The Mars Science Laboratory (MSL), however, has improved features that have opened up more areas for exploration. For example, it is larger and more robust than the MERs and is powered by nuclear fuel, allowing it to operate year round without the need for continuous solar power.

The Mars Science Laboratory will be winched down to the Martian surface by a sky crane. Image: NASA/JPL.

The rover will be lowered to the Martian surface via a new ‘skycrane’ technology, similar to how helicopters maneuver large objects through terrestrial skies. This method can accommodate more slope than the airbag method used for Spirit and Opportunity, and can be adjusted last minute to avoid any potentially hazardous boulders, for example. The target landing area is also considerably reduced from a safe area of about 70 kilometres for the MERs to a landing ellipse of just 20 kilometres for MSL.

"Landing on Mars always is a risky balance between science and engineering. The safest sites are flat, but the spectacular geology is generally where there are ups and downs, such as hills and canyons. That's why we have engineered this spacecraft to make more sites qualify as safe," says MSL mission manager Michael Watkins. "This will be the first spacecraft that can adjust its course as it descends through the Martian atmosphere, responding to variability in the atmosphere. This ability to land in much smaller areas than previous missions, plus capabilities to land at higher elevations and drive father, allows us to consider more places the scientists want to explore."

The mission plan calls for the rover to spend a full Martian year (23 months) examining the environment with a diverse payload of tools. The primary goals of the mission will be to characterise the local geology of the landing site and to determine whether life ever arose on the red planet. It will also characterise the climate of Mars and help prepare for human exploration. In order to fulfill these goals, MSL will complete a series of science objectives, such as determining an inventory of organic material and the chemical building blocks for life, and identifying features that might represent the effects of biological processes. MSL will also interpret the processes that have formed or modified rocks and soils at the landing site and surrounding area. The atmospheric measurements will help to assess the present state, distribution and cycling of water and carbon in the planet, and to help prepare for human visitors MSL will determine the nature and amount of radiation received on the Martian surface.

The Mars Science Laboratory will be much larger than previous Mars rovers Spirit and Opportunity. Image: NASA/JPL.

MSL is currently scheduled for launch in September 2009, arriving at the red planet in the summer of 2010. More information about the mission can be found in the Astronomy Now 2009 Yearbook, on sale now.

from:http://astronomynow.com/081120SiteselectionnarrowsfornextMarslander.html

Synchronised observations catch flares from Sagittarius A*

2008-12-21T03:42:00.000-08:00

Simultaneous observations made with the VLT and APEX telescopes have revealed the nature of four violent flares emanating from the centre of our Milky Way Galaxy.

Astronomers used ESO’s Very Large Telescope (VLT) and the Atacama Pathfinder Experiment (APEX) to study the region around the Milky Way’s black hole, known as Sagittarius A*, at near-infrared and sub-millimetre wavelengths respectively. Sagittarius A* is a supermassive black hole lurking at the centre of the Milky Way, and boasts a mass of about four million times that of the Sun. Emission from the galactic monster is thought to come from gas thrown off by proximal stars via a strong stellar wind, which then orbits and falls into the jaws of the black hole. Around four to six flares are observed from Sagittarius A* at infrared wavelengths every day.

Colour composite image of the central region of our Milky Way galaxy, about 26,000 light years from Earth. Giant clouds of gas and dust are shown in blue, as detected by the LABOCA instrument on the APEX telescope at sub-millimetre wavelengths. The image also contains near-infrared data from the 2MASS project at K-band (in red), H-band (in green), and J-band (in blue). The image shows a region approximately 100 light-years wide. Image: ESO/APEX/2MASS/A. Eckart et al.

"Only for this one object can our current telescopes detect these relatively faint flares from material orbiting just outside the event horizon," says Frederick Baganoff of the Massachusetts Institute of Technology (MIT). The event horizon marks the boundary beyond which no matter or radiation can escape the gravitational field of the black hole. While supermassive black holes are thought to exist in all galaxies, Sagittarius A* is the nearest one that astronomers can study in such detail.

Making the simultaneous observations required careful planning between teams at the two locations, and is the first time that astronomers have caught a flare by synchronising their observations in this way. "Observations like this, over a range of wavelengths, are really the only way to understand what's going on close to the black hole," says lead astronomer Andreas Eckart of the University of Cologne.

Over a period of six hours the VLT team detected extremely variable emission at infrared wavelengths, with four major flares erupting from Sagittarius A* in that time. The sub-millimetre wavelength results also showed flares, but crucially, they occurred about one and a half hours after the infrared flares. The astronomers put this down to the fact that the clouds of gas that are emitting the flares are expanding rapidly at rates of five million kilometres per hour. This expansion causes changes in the character of the emission over time, resulting in the time delay between the infrared and sub-millimetre flares.

Artist impression of a bright blob of gas in the disc of material surrounding the black hole in the centre of our Galaxy, Sagittarius A* and responsible for the flares detected in this study. As the blob orbits the black hole, it is stretched out, and this expansion over time causes the delay between flares being detected at near-infrared wavelengths (with the VLT) and at sub-millimetre wavelengths (with APEX). Image: ESO/L. Calçada.

The speed of the expansion, while fast, is actually only 0.5 percent of the speed of light, and provides more insight into the nature and cause of the flares. In order to escape from the immensely strong gravity that surrounds the black hole, the gas would have to be travelling at half the speed of light – 100 times faster than that detected – and so the researchers conclude that the gas cannot be streaming out in a jet from the black hole itself. Instead, they suspect that a ‘blob’ of gas orbiting close to the black hole is being stretched out and this is causing the expansion, and therefore the time delay between flares being detected by the VLT and APEX.

By simultaneously carrying out observations at different wavelengths, the astronomers have created a powerful tool to reveal the nature of flares emitted in the regions of black holes. As a next step, Eckart and his team hope to make further observations that will allow them to develop their proposed model for flare emission, and discover more about this mysterious region at the centre of our Galaxy.

from:http://astronomynow.com/081119synchronisedobservationscatchflaresfromSagA.html

1000 telescopes for schools

2008-12-21T03:41:00.000-08:00

In an ambitious project led by the Society for Popular Astronomy (SPA), the Science Facilities and Technology Council (STFC) and the Royal Astronomical Society (RAS), 1000 telescopes will be donated to secondary schools in the UK to inspire the next generation of astronomers throughout the International Year of Astronomy.

The landmark project, Telescopes for Schools, is just one part of the global effort to celebrate the International Year of Astronomy (IYA 2009), which commemorates the 400th anniversary of Galileo's first use of the telescope for astronomy, as well as the 40th anniversary of the first Moon landings. An English astronomer, Thomas Harriott, also first used a telescope to observe the Moon 400 years ago.

Four centuries later, the Telescopes for Schools project aims to inspire another generation of astronomers by enthusing pupils in subjects like physics and mathematics. "We think every pupil should have the chance to look through a telescope, an experience they will remember for the rest of their lives," says SPA President Helen Walker. "The UK has a flourishing community of amateur and professional astronomers. Through Telescopes for Schools they can share their enthusiasm with our young people."

Children at the Glasgow Science Centre enjoying a first look through one of 1000 free telescopes set to be delivered to UK schools. Image: International Year of Astronomy 2009, UK.

Schools can apply for one of the 70mm refractor telescopes via the SPA’s Moonwatch website at www.popastro.com/moonwatch, designed to support the project. The participating schools will also receive a DVD with clips explaining how to use their telescope and what they can look at, as well as interviews with enthusiastic astronomers and additional support materials for teachers. The schools are encouraged to find a local astronomer to help them use the telescope, but if the school does not know any local astronomers, the SPA has undertaken to try and find one from the communities of amateur and professional astronomers.

"The UK is a world leader in astronomy and we aim to use IYA 2009 to provide a launch pad to stimulate public interest in astronomy and the night sky and to encourage the take-up of science and technology in schools,” says Professor Ian Robson, who leads the IYA 2009 activities in the UK. “The launch of this project is tremendously exciting and I look forward to the excitement it will generate."

The Telescopes for Schools project will allow students to follow in Galileo's and Harriott’s footsteps and look at craters on the Moon or the satellites of Jupiter, and many other night sky objects including the rings of Saturn, bright clouds of gas and dust (nebulae), star clusters and even other galaxies. "The telescopes will give you a better understanding of the wider Universe," says RAS President Professor Andy Fabian

from:http://astronomynow.com/0811191000telescopesforschools.html

Scientists dive deeper into Mars’ watery past

2008-12-21T03:38:00.000-08:00

An international team of scientists working with data gleaned from Mars Odyssey’s Gamma Ray Spectrometer report new evidence for the controversial idea that oceans once covered as much as one-third of ancient Mars.

Today, on the Earth, oceans occupy around two-thirds of our planet, but all of the Martian oceans have long since dried up. Although the fleet of spacecraft and landers visiting Mars since the 1970s have demonstrated widespread evidence for a watery past, planetary scientists find it considerably challenging trying to identify ancient ‘shorelines’ on Mars, since they look a lot different to those we are more familiar with on Earth. For example, Earth's well-defined coastal shorelines are largely a direct result of powerful tides caused by gravitational interaction between Earth and the Moon, but Mars lacks a sizable moon that could have exerted such a force on the planet. In addition, that lakes or seas on Mars could have formed from giant debris flows and liquefied sediments, and Martian oceans may have been ice-covered, which would prevent any wave action and subsequent erosion of the coastline.

This 3D map superimposes gamma ray data from Mars Odyssey's GRS onto topographic data from the laser altimeter onboard the Mars Global Surveyor. The red arrow indicates the shield volcanoes of Elysium rise in northern Mars. Blue-to-violet colours mark areas poor in potassium and red-to-yellow colours mark potassium-rich sedimentary deposits in the lowlands below the Mars Pathfinder landing site (PF) and Viking 1 landing site (V1).

In the new study, lead by University of Arizona planetary geologist James Dohm, the shorelines are based on past investigations using topographic measurements. The team used data from NASA’s Mars Odyssey spacecraft, in particular the Gamma Ray Spectrometer (GRS), which is capable of detecting elements buried as much as 33 centimetres below the surface of Mars by the gamma rays they emit, to delineate the ancient shorelines on Mars. The capability of the GRS was previously demonstrated in the ground-breaking discovery of water-ice near the surface throughout much of high-latitude Mars in 2002.

"We compared GRS data on potassium, thorium and iron above and below a shoreline believed to mark an ancient ocean that covered a third of Mars' surface, and an inner shoreline believed to mark a younger, smaller ocean," says Dohm. "Our investigation posed the question: Might we see a greater concentration of these elements within the ancient shorelines because water and rock containing the elements moved from the highlands to the lowlands, where they eventually ponded as large water bodies?"

Results from Mars Odyssey and other spacecraft suggest that past watery conditions likely leached, transported and concentrated such elements as potassium, thorium and iron into the lowlands. The team found that the potassium-thorium-iron enriched areas occur below the older and younger ocean boundaries with respect to the entire region. "In other words, GRS elemental information is consistent with the ancient aqueous activity documented in the literature, such as the transferral of volatiles and rock materials to the northern plains and the formation of lakes and oceans in the northern plains, which includes marine deposits that either remained unburied and/or are exposed by erosion and deformation," Dohm tells Astronomy Now. "The regions below and above the two shoreline boundaries are like cookie cutouts that can be compared to the regions above the boundaries, as well as the total region."

An illustration showing the location of the Tharsis volcanic region and Valles Marineris in the context of the hypothesized larger, ancient ocean and smaller, more recent ocean in Mars' northern lowland planes. It is argued that Tharsis volcanism unleashed great floods that carved large outflow channels and deposited sediment carried from the southern cratered highlands to the northern lowland plains, where water formed lakes and oceans and changed climate for thousands of years.

The research team liken the younger inner shoreline to an ocean ten times the size of our Mediterranean Sea that existed on the northern plains of Mars a few billion years ago, and think that the larger, more ancient shoreline that covered a third of Mars held an ocean about 20 times the size of the Mediterranean.

Understanding how and when water existed on Mars is crucial in determining the habitability of the red planet, since water is a vital ingredient for life as we know it. The debate as to the possible existence of ancient Martian oceans marked by shorelines has been a colourful area of discussion for over twenty years. A trigger for global oceans, according to a report by Professor Victor Baker and colleagues at the University of Arizona Lunar and Planetary Laboratory, is that erupting magma caused extreme heating, and therefore resulted in vast areas of ice melting and unleashing floods that ponded in the northern lowlands of Mars, forming seas and lakes.

“Several investigators hypothesize that before the magmatic-driven release, the ice begins to melt and carbon dioxide gases begin to build below impermeable ice somewhat like a lid - think of shaking a pop can,” explains Dohm. “Eventually, the carbon dixoide-charged water is released catastrophically in floods of enormous magnitudes.”

The latest analysis of GRS data adds key information to the long-standing oceans on Mars controversy. "But the debate is likely to continue well into the future, perhaps even when scientists can finally walk the Martian surface with instruments in hand, with a network of smarter spaceborne, airborne and ground-based robotic systems in their midst,” says Dohm

from: http://astronomynow.com/081119scientistsdivedeeperintoMarswaterypast.html

XMM and Integral unveil magnetar environment

2008-12-02T09:32:00.000-08:00

X-ray and gamma ray data from ESA's XMM-Newton and Integral orbiting observatories have been used to make the first tests of the physical processes that define magnetars, an unusual class of neutron star with immense magnetic fields.

Neutron stars are the remnants of stars 10-50 times more massive than our Sun that have collapsed in on themselves such that the equivalent mass of our Sun is concentrated into a sphere just 20 kilometres in diameter. Neutron stars are also defined by their extremely fast rotation and ultra-strong magnetic field. Magnetars are a sub-class of neutron star that boast magnetic fields a thousand times stronger than that of ordinary neutron stars, and in total, astronomers know of just 15 such magnetic powerhouses.

X-ray and gamma ray data from ESA’s XMM-Newton and Integral orbiting observatories have been used to test, for the first time, the physical processes thought to lie behind the emission of magnetars, an atypical class of neutron stars with ultra-strong magnetic fields. Image: 2008 Sky & Telescope/Gregg Dinderman.

A magnetar’s magnetic field is so great that it is thought to be capable of twisting its own stellar crust, producing a current in the form of an electron cloud which flows around the star. These currents interact with the radiation coming from the stellar surface, producing X-rays which are observed by satellites such as XMM-Newton and Integral.

Until now, the electron clouds around magnetars were just a theoretical prediction, since it is not possible to produce such ultra-strong magnetic fields in laboratories on Earth. Dr Nanda Rea from the University of Amsterdam and colleagues have now demonstrated the presence of electron clouds around the whole set of known magnetars by building a theoretical code which takes into account the effect of these clouds, and then applying this code to X-ray and low energy gamma ray observations from XMM-Newton and Integral of all 15 magnetars.

“This model could perfectly fit all the data on these objects, resulting in a measurement of the electron density and temperature in the magnetosphere of these big magnets,” Rea tells Astronomy Now. “Their presence demonstrate that indeed the theoretical prediction of a twisted magnetosphere is correct, and that their peculiar X-ray emission (with respect to normal neutron stars) is in great part due to these electron clouds 1000 times denser than in normal neutron stars.”

The results have established an important link between an observed phenomenon and an actual physical process, and the team is now working hard to develop and test more detailed models to fully understand the behaviour of matter under the influence of such strong magnetic fields
from:http://astronomynow.com/081117XMMandIntegralunveilmagnetarenvironment.html

Scientists dive deeper into Mars’ watery past

2008-12-02T09:31:00.001-08:00

The latest analysis of GRS data adds key information to the long-standing oceans on Mars controversy. "But the debate is likely to continue well into the future, perhaps even when scientists can finally walk the Martian surface with instruments in hand, with a network of smarter spaceborne, airborne and ground-based robotic systems in their midst,” says Dohm
from:http://astronomynow.com/081119scientistsdivedeeperintoMarswaterypast.html

Planet family photographed around normal star

2008-12-02T09:31:00.000-08:00

Astronomers using the Gemini North telescope and W.M. Keck Observatory on Hawaii's Mauna Kea have obtained the first images of a multi-planet system around a normal star.

"We finally have an actual image of an entire system. This is a milestone in the search and characterisation of planetary systems around stars," says Bruce Macintosh of the Lawrence Livermore National Laboratory.

Gemini Observatory discovery image showing two of the three confirmed planets indicated as b and c. b is the ~7 Jupiter-mass planet orbiting at about 70 AU; c is the ~10 Jupiter-mass planet orbiting the star at about 40 AU. Due to the brightness of the central star, it has been blocked and appears blank in this image to increase visibility of the planets. Image: Gemini Observatory

The new solar system orbits a dusty young star known as HR 8799, which is 140 light years away and about 1.5 times the size of our Sun and five times more luminous. Three planets, two roughly ten times and one seven times the mass of Jupiter orbit the star at distances equivalent to 24, 37 and 67 times the Earth-Sun separation (1 astronomical unit, or AU). Moreover, the size of the planets decreases with distance from the parent star, much like the giant planets do in our own Solar System. The furthest planet in the system orbits just inside a disc of dusty debris, similar to that produced by the comets of the Kuiper belt of our Solar System, just beyond the orbit of Neptune at 30 AU. The discovery team have commented that the system seems to be a scaled up version of our Solar System orbiting a slightly larger and brighter star.

"Seeing these planets directly – separating their light from the star – lets us study them as individuals, and use spectroscopy to study their properties, like temperature or composition," says Macintosh. "We can see some evidence for complex cloud structure in their atmosphere and soon we'll be able to get spectra, and say something about composition."

Using the Gemini North telescopes, the international team made the initial discovery of two of the planets in the planetary system in October 2007. Follow-up observations with the Keck II telescope confirmed the discovery and discerned a third planet orbiting even closer to the star. In both cases, adaptive optics technology – with a resolution of 0.4 seconds of arc – was used to correct in real-time for atmospheric turbulence to obtain these historic infrared images of an extrasolar multiple planet system.

Naked eye and binocular finder charts for HR 8799. The host star is faintly visible to the naked eye, but only to those who live well away from bright city lights or have a small telescope or even binoculars. Image: Gemini Observatory Illustration by Stephen James O'Meara.

"Until now, when astronomers discover new planets around a star, all we see are wiggly lines on a graph of the star's velocity or brightness. Now we have an actual picture showing the planets themselves, and that makes things very interesting," says Macintosh.

The host star is a bright, blue, A-type star, which are often ignored in ground and space-based direct imaging surveys since they offer a less favorable contrast between a bright star and a faint planet. But their advantage over the Sun is that they can retain heavy discs of planet-making material and therefore form more massive planets at wider separations that are easier to detect. Indeed, as Ben Zuckerman of UCLA comments: "HR 8799's dust disc stands out as one of the most massive in orbit around any star within 300 light years of Earth." HR 8799 is also young – less than 100 million years old – which means its planets are still glowing with heat from their formation.

The observations of HR 8799 form part of a larger survey of 80 such young, dusty and massive stars located in the solar neighborhood. This discovery was made after observing only a few stars, which may lead to the conclusion that Jupiter-mass planets at separations similar to the giant planets of our Solar System are frequent around stars only a bit more massive than the Sun. What is certain is that HR 8799's planetary system will be studied in great detail in the years to come, and will undoubtedly be a prime target for next-generation exoplanet-finding instruments and dedicated space missions. Ultimately, astronomers are working towards images and spectroscopic studies of truly Earthlike planets.

Artist impression of the multiple planet system, that hosts three planets of 10, 10 and 7 times Jupiter mass. Image: Gemini Observatory Artwork by Lynette Cook.

"After all these years, it's amazing to have a picture showing not one but three planets. The discovery of the HR 8799 system is a crucial step on the road to the ultimate detection of another Earth," says Macintosh. "I think there's a very high probability that there are more planets in the system that we can't detect yet. One of the things that distinguishes this system from most of the extrasolar planets that are already known is that HR 8799 has its giant planets in the outer parts – like our solar system does – and so has 'room' for smaller terrestrial planets – far beyond our current ability to see – in the inner parts."

The article is published in the 13 November 2008 issue of Science Express
from:http://astronomynow.com/081114Planetfamilyphotographedaroundnormalstar.html

Hubble images exoplanet

2008-12-02T09:30:00.000-08:00

Using the Hubble Space Telescope, a team of astronomers has taken an image of a planet around the star Fomalhaut. It is the first such image of an exoplanet taken in visible wavelengths. The results have been published today in the journal Science.

Fomalhaut lies 25 light years away in the constellation Piscis Austrinus, the Southern Fish, and is surrounded by a striking debris ring. The planet, Fomalhaut b, resides inside this ring and orbits the star at a distance of 119 astronomical units (an astronomical unit, AU, being the distance between the Earth and the Sun). In other words, Fomalhaut b orbits its star at nearly four times the distance that Neptune does from the Sun. Previous Hubble images of the debris ring have shown it to bear an uncanny resemblance to the ‘eye of Sauron’ from the Lord of the Rings films.

This 2006 Hubble Space Telescope optical image shows the belt of dust and debris (bright oval) surrounding the star Fomalhaut and the planet (inset) that orbits the star every 872 years and sculpts the inner edge of the belt. A coronagraph on the Advanced Camera for Surveys blocks out the light of the star (centre), which is 100 million times brighter than the planet. Image: Paul Kalas, UC Berkeley/NASA/ESA.

Professor Paul Kalas of the University of California, Berkeley, has been studying the Fomalhaut system for 15 years. He first imaged Fomalhaut’s debris belt in 2005 using Hubble’s Advanced Camera for Surveys, and quickly noticed that the belt had a sharp, inner edge. "The gravity of Fomalhaut b is the key reason that the vast dust belt surrounding Fomalhaut is cleanly sculpted into a ring,” he says. This is similar to the way that Saturn’s rings are kept trim by the activity of its moons. It has taken three years to obtain two images of Fomalhaut b. But with these images, Kalas has been able to show that the planet has an annual orbit of 872 years, correlating exactly with its distance from the star.

And it gets even more interesting. Kalas and his team detected a dip in the planet’s brightness by half a stellar magnitude in the time that the two images were taken. What could be the explanation? Hot gas from the debris ring around the planet, and a hot outer atmosphere heated by convective cells, have both been touted as explanations. But could the dip also be due to a moon passing in front of the planet? “That would be one exotic possibility that requires future observations to either confirm the idea, or exclude it,” Kalas says
from:http://astronomynow.com/081114Hubbleimagesexoplanet.html

Exclusive Interview: Richard Garriott:Space tourist

2008-12-02T09:29:00.000-08:00

Richard Garriott, a significant figure in the video game industry, recently established himself as a self-funded space tourist, spending ten days onboard the International Space Station (ISS) in October. Astronomy Now’s Website Editor Emily Baldwin spoke to Garriott about the highs and lows of his space station experiences, and his thoughts on the future of space tourism.

What inspired you to want to take on the challenge of training as an astronaut and to go into space?
I think everybody, at some time in their life, imagines they might want to travel into space, so in that way I don’t think I was any different to anyone else. What was different for me is not only was my father an astronaut [Owen Garriott] which made it seem more practical, but also, when I was a teenager, a NASA physician told me I would not be eligible to be a NASA astronaut because of my poor eyesight. For me, instead of making the dream go away, it made me think “wait a minute, you can’t tell me I’m not allowed to go into space” and so I worked ever since then to privatise space and find a way for private citizens to get there, and of course most especially me.

How long did you have to train for, and what preparations did you have to make in order to be ready for the trip?
My training has been most of 2008, and my training here in Russia has mostly been what you might consider intellectual training. That is, learning all the systems onboard the Soyuz and the Space Station to make sure I could operate safely and independently, as well as practice all the experiments I wanted to do. But even before that I had medical preparations to do, where you have to learn about the physiological challenges of living in space, which are considerably greater than what people might expect.

Did you encounter any difficulties with your health that you weren’t expecting?
There were some challenges that I didn’t realise in advance how significant they would be. For example, about 80 percent of people who go into space get what is called space adaptation sickness, which a lot of people think of as motion sickness. I actually didn’t have that because the Russians have a very nice preparation scheme for acclimatising yourself to potential motion sickness that helped me. But on the other hand there is another effect that occurs, called a fluid shift, that when you live in zero-g it kind of feels like you’re hanging upside down on monkey bars. And when you hang upside down for say five minutes you can feel the extra fluid pressure in your head but it doesn’t really bother you. But if you can imagine doing that for five hours or five days you can imagine that it can become particularly uncomfortable. And so for the first five days I felt like I had a head cold, and I really didn’t feel too comfortable. Also your stomach and intestines basically shut down when you’re in space and so you feel a little sick and just not really yourself. A lot of people describe those effects as fairly normal when in space.

What was your role in the mission?
I really had three main areas. One was to prove or demonstrate that as a private astronaut I could still contribute scientifically and commercially like a career astronaut. So I did a variety of experiments and one which was probably the most scientifically interesting was called Protein Crystal Growth where I grew a very large number of protein crystals which are now being studied on the ground and which I believe will contribute significantly to the understanding of this very important science that really stands a good chance of advancing the medical field in a very important way. [The proteins have important cellular functions that are usually associated with common human diseases, and the weightless environment of space allows large crystals to grow, enabling researchers to learn more about their molecular structure and how they can be used to develop drugs to combat disease]. I also spent a good deal of my time doing second generation experiments. Since my father was an astronaut and took photos of the Earth, I worked with a group called the Nature Conservancy to study those NASA photographs to find places I could or should photograph myself from space to showcase how the Earth has changed in 35 years in one generation of space flight. And then there were educational activities. In fact, I spent almost 30 percent of my time on orbit doing educational experiments and answering educational questions. I worked with the British National Space Centre as well as the Challenger centres and did experiments for the teachers and the students. I also connected by ham radio [amateur radio] to students all around the globe. And finally I did what we call 'personal symbolic activities', in particular I did an art show on orbit and I even created a science fiction movie.

Garriott used some of his personal time to put on an art show.

Image: www.richardinspace.com.

You also ran a competition for children to design some experiments for you to carry out in space. What were some of the things they came up with?
We had a contest with a variety of different age groups. The oldest kids proposed future plans to take advantage of space that weren’t necessarily things I could do in a short duration orbit, but they were designing things like hotels and buildings in orbit that might accommodate larger numbers of people. And for the slightly younger kids they had me doing experiments like what happens in your daily routines, like when you brush your teeth, wash your hair, rinse your mouth out and so on. Basically, how can you rinse your mouth out without a sink to spit into, for example? And so they had me doing some experiments relating to life in space. The very youngest kids asked me very insightful questions that were actually quite tricky to answer, like is it hot or cold in space? Of course space is a vacuum and so as such has no inherent temperature of its own. Its temperature is actually the measure of energy or motion of the molecules of a medium like the surface you might touch. So in space if you’re in a shadow like behind the space station or behind the Earth it can get very cold very quickly as you radiate your heat away, and in the sunlight you absorb that heat and the vacuum around you, which is a great insulator, gets hotter and hotter and you would overheat very quickly. So space really has no temperature but you get cold in the shade and hot in the Sun.

How do things ‘work’ on the space station?
Life is dependant on a number of things onboard the station. For example you have to have electrical power – there are giant solar panels all over it, giant batteries in some of the main areas of the station, and yet what’s interesting is that there’s no voltmeter because it’s all managed from the ground, so it just works and some people on the ground keep an eye on it so you don’t have to. Another thing that’s really important is having enough oxygen. There’s a system that works through electrolysis, these water tanks get brought up and get split into hydrogen and oxygen, and the hydrogen is vented outside and oxygen is brought into the main cabin, but there’s no oxygen gauge. Another thing that’s really important is to get rid of the carbon dioxide, but there’s no carbon dioxide gauge! All these things you can find – you can go to a laptop and bring it up and look at the displays but there’s no really obvious in front of you gauge. Same with temperature – there’s no thermostat on the air conditioning system for example. The systems are incredibly well designed, they just operate themselves, and they’re monitored by the ground and it’s only in the very extreme conditions do they notify the crew and say “hey, there’s something you might need to take a look at.” Otherwise it just works. For example on the few days I spent on Soyuz, it’s designed astoundingly well such that you don’t have to turn on air conditioning or heating, it just works by itself. It’s insulated well enough that it retains its own temperature. Any excess heat is automatically dumped through radiators and you’ve got little heaters that are also operating to make sure things don’t get too cold. And it all just operates automatically without any human interaction.

What was it like when the toilet broke?
Actually they had cured the toilet by the time I got onboard. However, you hear that the most common question kids ask is how do you go to the bathroom in space? But having not been an astronaut before, when I got over here [to Russia] one of the questions I had is how do you go to the bathroom in space? It’s funny, because even amongst astronauts and cosmonauts, one of the most common dinner time conversations is using the bathroom and what parts are easy and what parts are difficult. Liquid collection is really no problem, it’s basically a funnel with a vacuum behind it that you pee into, and the only challenge is how to keep yourself floating away while you’re trying to hold the funnel in front of you. Technically a little challenging but it’s no big deal. On the other hand, dealing with the solid waste is quite a bit more challenging. The method is still basically the same, but you sit on a miniature toilet which is lined with a plastic bag with perforations on the bottom, and there’s a fan below that is there to pull things into the bag. However it doesn’t really work that well, it doesn’t respond in the same way that gravity assists you in getting rid of solid wastes on the Earth. So that is an area that requires additional strategies!

NASA astronaut Greg Chamitoff (left) and Richard Garriott pose for a photo in the Zvezda Service Module of the International Space Station. Image: NASA.

What was the most interesting thing you saw on the Earth

from space?
One was the San Francisco bay area. One of the things that was really striking was still how close to the Earth we were in spite of being as high up as we were [the ISS orbits at an altitude of about 350 kilometres]. As you look to the horizon you can see the blackness of space and the curvature of the Earth, and the thin veil of the atmosphere on top of the Earth, but looking straight down you can still see airports, air plane contrails, the clouds, I could still see all the ship wakes going in and out of the Bay area, I could see the Golden Gate Bridge and the Oakland Bay Bridge, all easily viewable from space. It was interesting to realise how still intimately close you were with the Earth. And you hear how man made objects are difficult to see from space, – at least from low Earth orbit that’s just not true. You can see the Palm islands in Dubai and the New World Islands very easily by eye. You see weather systems in a completely different way because you could see that from horizon to horizon they interact with each other in ways you would not see from the ground. Also you can see the geological interaction of the planet, like plate tectonic movement, – it really does appear like one continuous flowing surface of the Earth. And even how humanity has pretty much inhabited all the fertile areas of the Earth is really quite apparent from viewing it from space.

What was a typical day like for you?
Well, we ignored bed time but apart from that we had a pretty good schedule! We would get up at 5am GMT, we’d spend an hour and a half having breakfast and doing morning hygiene routines and printing out our daily schedule and preparing for work. At 6.30 or 7am we’d start our work day and everyone had independent schedules. The work days were quite full, but we all got together for lunch and dinner, and after dinner was largely our own to do our personal projects which tended to run until midnight or 1am. And then you get a bit of rest before starting again a few hours later!

What were the highs and lows of your trip?
A low point would be on flight day 5 I woke up with a horrific headache that lasted the whole day. There was some debate as to what the cause was but one possibly is that because you sleep in a sleeping bag, and for at least a little bit of the time in that particular night I’d brought my face into the sleeping bag which tends to mean you breathe in and out the same air, so basically I had carbon dioxide poisoning. So I felt really poorly that day. The highlight would probably be my ham radio activities. I talked to over 500 individuals around the globe and had about a dozen contacts with school groups to answer questions. I was also sending lots of slow scan television images down by ham radio and it became very clear early on that people all around the globe were really paying pretty close attention to my flight and observing all the ham radio images I sent down, and were making commentary to me about the images, or how much they were enjoying following along, and getting the chance to talk with me. And I was really very, very moved, especially in the last few days when I spoke to classrooms full of kids, who’d only be online for 30 seconds and would all say “Hi Richard, bye Richard, have a good trip home,” all together. It was really very, very special.

What were launch and re-entry like?
The launch and re-entry of course are both very special times, just like living on the Space Station itself. Launch is very smooth, it doesn’t feel dangerous in any way and it doesn’t overload your body too much. The g-forces went up to about 4.5g but you don’t feel uncomfortable in any way, you just feel like it’s eight minutes of very confident lifting from behind, lifting into the sky by this amazing vehicle that doesn’t shudder or shake or give any indication of the astounding difficulty of reaching space. Re-entry again feels much more confident and comfortable than I expected but the view is really spectacular. When you’re coming in through the upper atmosphere and seeing the heat shield burn off and the plasma outside the window, it’s really astounding. And when the main parachutes open, the whole vehicle is like it’s on the end of very big whip that gets cracked; you get rolled around with some significant jostling, and after that you’re just drifting down quite comfortably under a canopy until you get down to the ground. The vehicle hitting the ground is like a 30mph car crash, but what’s interesting is that you’re in a seat that’s perfectly moulded to your body and it has shock absorbers, so landing’s actually really comfortable. But the vehicle around you takes a significant impact, but really it’s not particularly alarming, it’s just noticeable.

Weather systems can be seen in a totally different way from 380 kilometres above the ground! This is Hurricane Ike, taken by crew onboard the ISS in September. Image: NASA.

How do you think space tourism will be developed in the future, and could we eventually be making trips into space as regularly as 'normal' destination holidays?
The more I’ve learnt about this the more I can break space travel into a few categories. So first there is sub orbital spaceflight which is going to become commercial in the next few years. I believe the ultimate price for those flights will come down to into the tens of thousands of dollars. Which means if you can afford a first class ticket for a vacation across the other side of the planet, you’ll be able to afford instead a flight to space, so a lot of people will be able to take sub orbital space flights. However, the speeds and energies involved to get all the way into orbit and back are considerably more daunting so I don’t think that that’s going to become cheaper than millions of dollars any time soon. So therefore it will either stay in the hands of wealthy individuals, or what I hope happens and this is what I’m hoping to work towards, is that I can demonstrate that there are things to do in orbit that are worth putting people there for, and not because they are sponsored by the government. For example, we spend a lot of money putting someone on an oil rig to bring back oil because oil’s worth it. And as soon as there’s things to do in space that are worth doing then that will take a lot of people into space, not just as vacation but for people to live and work.

What advice would you give a school age student wanting to become an astronaut?
I would say, to either go privately or to go as a government sponsored professional, the advice is pretty similar. One of the things that made this appropriate for me, in the sense that it allowed me to train and work as a crew member and being accepted as a private flyer by my crew, is that I have a very diverse background. I enjoy subject matter across the board from science to history to math, and that really has been helpful in making my journey successful. That also happens to be important if you want to apply for a job as an astronaut, and it happens to be important if you want to be a successful entrepreneur, which allowed me to afford myself this opportunity to go into space. So for kids, enjoy your classes, enjoy as many different areas of knowledge that you can, pick up as much as you can in as many fields of knowledge as possible. Find something to do that you really love. I’m really lucky I’m doing computer games in my case, which I’m really passionate about and really love, and when you know a subject well enough and are passionate enough about it, you do well at it, and so I think that’s what helped me be successful in this industry and ultimately has taken me into space.

Do you have any plans to make further trips into space?
Of course I do hope I do get to come back, but I believe it will most likely be when I can put a business plan together, so to speak, that will pay for my trip to space rather than coming out of my own pocket. It will be a few years, but as soon as possible.

You can read more about Richard Garriott and his space adventures at: www.richardinspace.com

from:http://astronomynow.com/081113RichardGarriottInterview.html

Mysterious new aurora

2008-12-02T09:25:00.000-08:00

An infrared camera on the Cassini spacecraft has detected a unique aurora at Saturn’s north polar cap, unlike any other known in the Solar System.

"We've never seen an aurora like this elsewhere," says Tom Stallard of the University of Leicester, and lead author of a paper released today in the journal Nature. "It's not just a ring of aurorae like those we've seen at Jupiter or Earth. This one covers an enormous area across the pole. Our current ideas on what forms Saturn's aurorae predict that this region should be empty, so finding such a bright one here is a fantastic surprise."

The image shows both a bright ring, as seen from Earth, as well as an example of bright auroral emission within the polar cap that had been undetected until the advent of Cassini. Silhouetted by the glow (shown here in red) of the hot interior of Saturn are the clouds and haze that underlie this auroral region. Image: NASA/JPL/University of Arizona.

Auroras are caused by the collision of charged particles streaming along the magnetic field lines of a planet into its atmosphere, and give rise to the spectacular Northern Lights or the aurora borealis on Earth (and similarly the aurora australis in the south polar regions, too). Most aurorae appear green and red due to emissions from atomic oxygen.

For the giant planets Jupiter and Saturn, the majority of aurora are caused by particles trapped within the magnetic environments of those planets. Jupiter's main auroral ring, caused by interactions internal to Jupiter's magnetic environment, is constant in size, while Saturn's main aurora, which is caused by the solar wind, undergoes dramatic size changes as the wind varies. The newly observed aurora at Saturn's north pole, however, does not fit into either category.

"Saturn's unique auroral features are telling us there is something special and unforeseen about this planet's magnetosphere and the way it interacts with the solar wind and the planet's atmosphere," says Nick Achilleos, Cassini scientist based at the University College London. "Trying to explain its origin will no doubt lead us to physics which uniquely operates in the environment of Saturn."

Energetic particles, crashing into the upper atmosphere cause Saturn’s aurora (shown in blue in the image presented here) to glow brightly in infrared. This aurora, which defies past predictions of what was expected, is constantly changing, even disappearing within a 45 minute-period. Cassini’s infrared eyes found that the aurora sometimes fills the region from around 82 degrees north all the way over the pole
from:http://astronomynow.com/081113MysteriousnewauroraonSaturn.html

Dusty shock waves generate planet ingredients

2008-12-02T09:23:00.000-08:00

Using NASA’s Spitzer Space Telescope, astronomers have shown that shock waves around dusty young stars could be generating the raw materials needed for planet formation.

Astronomers detected tiny crystals, similar in make-up to quartz, around young stars just beginning to form planets. The cristobalite and tridymite crystals are already known to reside in comets, volcanic lava flows on Earth, and in some meteorites collected on Earth. They are thought to form in short-lived heating events followed by rapid cooling, conditions that are generated in shock waves.

Shock waves formed by colliding gas and dust in young planet-forming discs may force the creation of raw materials needed for planet growth. Image: ESO.

It is well known that planets are born out of swirling discs of dust and gas that surround young stars, building up from tiny grains into progressively larger planetisimals and eventually fully fledged planets in just a few millions of years. Forrest and colleagues used Spitzer to examine five young planet-forming discs around stars 400 light years away, and detected the high-temperature forms of silica, that is, cristobalite and tridymite, in planet forming discs for the first time. Silica is made of only silicon and oxygen and is the main ingredient in glass.

"Cristobalite and tridymite are essentially high-temperature forms of quartz," says Ben Sargent, one of the co-authors of the paper that describes the results that will appear in a future edition of the Astrophysical Journal. "If you heat quartz crystals, you'll get these compounds."

But these specific crystals require temperatures as high as 1,220 Kelvin to form, and the young planet-forming discs are only about 100 to 1,000 Kelvin, presenting something of a paradox. Since the crystals require a heating event that is followed by rapid cooling for their genesis, astronomers theorised that shock waves could be the culprit, creating violent, high speed collisions between the clouds of gas swirling around a young planetary disc and elevating the temperatures there.

"By studying these other star systems, we can learn about the very beginnings of our own planets 4.6 billion years ago," says William Forrest of the University of Rochester, New York.
"Spitzer has given us a better idea of how the raw materials of planets are produced very early on."

The findings are also in agreement with local evidence from our own Solar System. Spherical pebbles, called chondrules, found in ancient meteorites that have fallen to Earth are also thought to have been crystallised by shock waves in our Solar System's young planet-forming disc
from:http://astronomynow.com/081112dustyshockwavesgenerateplanetingredients.html

Sub-millimetre astronomy reveals glowing

2008-12-02T09:22:00.000-08:00

By using sub-millimetre wavelength astronomy, astronomers have revealed the cold dense clouds of material that are the birth places of new stars.

Astronomers using the LABOCA camera on the 12 metre Atacama Pathfinder Experiment (APEX) telescope detected clumps of cold gas four times fainter than ever seen before, and which had been forced to collapse as an expanding bubble of ionised gas about ten light years across swept through the region known as RCW120.

Colour composite image of RCW120. The submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas. Image: ESO/APEX/DSS2/ SuperCosmos.

RCW120 is located some 4,200 light years from Earth towards the constellation of Scorpius and hosts a hot, massive star in its centre. The star is emitting huge amounts of ultraviolet radiation, which ionises the surrounding gas, stripping the electrons from hydrogen atoms and producing the characteristic red glow of so-called H-alpha emission.

Accompanying the ionised region is a shock wave, which sweeps up a layer of the surrounding cold interstellar gas and cosmic dust. This layer becomes unstable and collapses under its own gravity into dense clumps, forming cold, dense clouds of hydrogen where new stars are born. Since the clouds are still extremely cold at just -250 degrees Celsius, their faint heat glow can only be seen at sub-millimetre wavelengths, demonstrating the importance of sub-millimetre astronomy in studying the earliest stages of stellar life. Moreover, since the brightness of the stellar clumps is a measure of their mass, this also means that astronomers can extend their studies to the least massive stars via sub-millimetre astronomy
from:http://astronomynow.com/081112submillitreastronomyrevealsglowingstellarnurseries.html

Phoenix concludes Martian adventure

2008-12-02T09:20:00.000-08:00

After more than five months on the Martian surface, NASA’s Phoenix Mars Lander has said its farewells to the Earth as the decline in solar power forces the spacecraft to shut down.

Phoenix last communicated with mission engineers on 2 November but there is still hope the lander will revive itself and phone home. In addition to shorter daylight hours, Phoenix must also contend with a dustier sky, greater cloud coverage and colder temperatures as the northern Mars summer turns to autumn.

One of Phoenix's major acheivements was finding a layer of ice just below the surface. The ice was seen to vapourise before its cameras in just a few Martian days. Image: NASA/JPL-Calech/University of Arizona/Texas A&M University.

Even though the practical side of the spacecraft’s work has concluded, mission scientists say that the analysis of data from the instruments is in its earliest stages. "Phoenix has given us some surprises, and I'm confident we will be pulling more gems from this trove of data for years to come," says Phoenix Principal Investigator Peter Smith of the University of Arizona.

Phoenix already notched up a first by landing farther north than any other spacecraft has dared on the Martian surface. Following its arrival on 25 May 2008, Phoenix has photographed, dug, scooped, baked, tasted and sniffed out the ingredients of the north polar soil, confirming the presence of water-ice in the Martian subsurface early in its mission. Phoenix is the first mission to directly ‘touch’ water-ice on Mars, which it found just a few centimetres below the surface, verifying the remote observations made by Mars Odyssey in 2002. The lander’s cameras returned over 25,000 images from panoramas to atomic level images of soil grains with the first atomic force microscope ever used outside Earth.

"Phoenix not only met the tremendous challenge of landing safely, it accomplished scientific investigations on 149 of its 152 Martian days as a result of dedicated work by a talented team," says Phoenix Project Manager Barry Goldstein at NASA's Jet Propulsion Laboratory. The mission was scheduled to last just three months, but continued for over five months.

During the first 90 Martian days after its May 25, 2008 landing in the north arctic plains of Mars, Phoenix dug several trenches in the workspace reachable with the lander's robotic arm. Image: NASA/JPL-Calech/University of Arizona/Texas A&M University.

One of Phoenix's science goals was to advance our understanding of Mars as a potentially habitable environment, either now or in the past. Supporting findings include documenting a mildly alkaline soil environment unlike any found by earlier Mars missions, finding small concentrations of salts that could be nutrients for life, discovering perchlorate salt, which has implications for ice and soil properties, and detecting calcium carbonate, a marker of effects of liquid water. Many of the minerals detected by both Phoenix and the Mars Exploration Rovers could only have formed in the presence of water, and scientists believe that by finding water, they will find clues to the history of life on Mars, should it ever have existed.

Phoenix also documented the Martian weather for the duration of the mission, observing snow descending from clouds, and providing extensive data on daily temperature, pressure, humidity and wind, as well as direct observations of haze, clouds, frost and dust devils. Coordinated with NASA's Mars Reconnaissance Orbiter, the duo performed simultaneous ground and orbital observations of Martian weather to provide context for both sets of recordings.

"Phoenix provided an important step to spur the hope that we can show Mars was once habitable and possibly supported life," says Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "Phoenix was supported by orbiting NASA spacecraft providing communications relay while producing their own fascinating science. With the upcoming launch of the Mars Science Laboratory, the Mars Program never sleeps."

Mars Science Laboratory will launch in late 2009 and will be winched down to the Martian surface by a rocket-powered ‘sky-crane’. The landing site has yet to be determined. You can read more about the Mars Science Laboratory in the Astronomy Now 2009 Yearbook, available to buy now
from: http://astronomynow.com/081111PhoenixconcludesMartianadventure.html

Early career planetary scientists explore Mars

2008-12-02T09:16:00.000-08:00

Martian meteorites, surface process and the habitability of the red planet formed a key part of discussions at the UK Planetary Forum’s 6th Early Careers Planetary Scientists’ meeting held in London last week. Emily Baldwin reports on three up and coming PhD students and their extraterrestrial research.

The question of if and when water existed on Mars and its role in the history of the red planet is probably one of the most sought after answers in planetary science. Susan Conway of the Open University is studying the formation mechanisms of gullies on Mars by looking at similar examples here on the Earth. She suggests that since the current low average temperatures and pressures on Mars prevent the formation of liquid water, the discovery of recently active gullies on the surface of Mars presents a paradox.

Gullies like this on the Earth are usually formed by flowing water, but on Mars liquid water is unstable. Research into what has created the recent gullies on Mars is an active area of research for current early career scientists. Image: Malin Space Science Systems, MGS, JPL, NASA.

“The process forming gullies on Mars is unknown and it is through investigating the morphology of analogous sites on Earth that we hope to either rule out certain processes or find evidence for them occurring on Mars,” says Conway. Conway and colleagues undertook fieldwork in the Westfjords of Iceland where gullies share similarities with those on Mars, in terms of their shape and sinuosity (how much they bend and curve).

“In Iceland the gullies we have studied are formed by debris flow, a process by which a slurry of mud, rocks and water surges downslope. This process forms very distinctive landforms,” she says. By studying the Icelandic gullies, and comparing them with others from around the world, Conway found that the characteristics of Martian gullies shared many similarities with the terrestrial counterparts, meaning that debris flow as an active process on Mars – and possibly even including water – cannot be ruled out just yet. However, there is still a lot of work to be done, and Conway plans to study more gullies to increase the dataset.

“If we can show the morphology of the gullies on Mars is sufficiently similar to debris flow then we have a strong case for saying this process has been recently active on Mars,” she says. “This shows liquid water must have been present on the surface in the recent past, highlighting either that our current understanding of the behaviour of water under present Martian conditions is lacking or that our interpretation of the recent Martian climate is wrong.”

Earlier this year debris flows were reported on scarps on Mars that appeared as bright deposits in images taken by various orbiting Mars cameras separated by just a few years. After the initial excitement that this could have provided evidence for water on Mars, it turns out that dry debris flows, similar to an avalanche on Earth, are the most likely culprit. “The debris falls reported earlier this year do not form gullies,” comments Conway. “Due to the cold temperatures in this region, it is likely that these flows were entirely dry mass wasting.”

By studying environments on the Earth where volcanic activity and ice interact, such as in Iceland as shown here, scientists can learn about the potential habitability of similar environments on other planets such as Mars. Image: Clare Cousins.

Moving to astrobiology, but sticking with the watery theme, Claire Cousins of the Centre for Planetary Sciences at University College London presented her work on the potential for microbial colonisation on Mars, specifically where buried ice interacts with volcanic processes to give potentially life-giving heat to an otherwise harsh, frozen environment. “After an eruptive episode, subglacial volcanic systems produce a number of different environments that can be colonised by microbial life,” describes Cousins. “These include solidified lava, a lens of meltwater (which can be sustained by hydrothermal heating once the lava has cooled), and the overlying ice.”

The combination of geothermal energy and liquid water within a subsurface setting make subglacial volcanic systems an excellent refuge for life on Mars. “The presence of large amounts of water-ice plus widespread evidence for basaltic volcanism on Mars suggests the two must have interacted at some point in Martian history,” she says.

By performing experiments with microbes in simulated Martian icy conditions – which consisted of -30 degress Celsius temperatures, UV radiation and low pressure – and then subjecting the experiment to heat, Cousins and colleagues showed that the production of meltwater between the lava sample and the overlying ice offered a suitable environment for colonisation. “This strongly suggests this environmental setting could have been habitable on Mars at a time when volcanic activity and glaciers interacted,” she says.

However, problems may arise within the initial colonisation of a system because of the potential instability of these environments. “Once geothermal heat flow diminishes, or the overlying glacier retreats, the environments no longer exist,” says Cousins. That means that although you may have suitable environments, you need to somehow get the microbes there in the first place. Cousins comments that several volcanic systems can exist beneath the same glacier, therefore microbes could be transported via meltwater traveling through fractures and channels within the ice, thereby offering a solution to this problem.

“There is a lot of evidence that suggests subglacial volcanic activity occurred throughout Martian history, driving the need to understand these systems and resulting environments more fully,” adds Cousins. To date, only the top few centimetres of Martian soil have been probed; future missions such as ExoMars will include a drill to dig even deeper, and perhaps uncover potentially habitable environments buried at depth.

There is a lot of evidence for volcanic activity in Mars' past. Could volcanic activity combined with an icy environment at depth provide the magic ingredients for life? Claire Cousins of UCL has been finding out. Image: NASA.

While we have yet to return samples of Martian soil to the Earth, meteorites originating from the red planet are the next best thing, and give Julia Cartwright of the University of Manchester the tools to learn about the atmospheric and geological history of the planet. She studies a type of meteorite known as shergottites that account for over 80 percent of known Martian meteorites and which display evidence of undergoing a violent history. By looking at the composition, ratio and location of minerals contained within a meteorite, and the gases trapped within them, scientists can learn about the environment in which the meteorite originally formed, including details of the planet’s atmosphere and interior at the time of their genesis.

“The gases are incorporated into meteorites at some point in their histories, though the locations and trapping mechanisms of these gases has been heavily debated,” says Cartwright. The current theories propose that gases can form either within the mineral grains themselves, on the boundaries between grains or on the surfaces of the mineral, which relate to the mechanisms that put them there: either by being dissolved in the same magma that formed the grain, altered by water or formed in a high pressure event such as an impact, respectively.

Cartwright’s work on four different shergottites can answer questions regarding her meteorites’ ages and possible source locations. “The shergottites have very similar, young formation ages of 200-500 million years suggesting that they may have been formed in the same region and from the younger units on Mars, which only constitute a small proportion of the Martian surface. The shergottites also have very similar ejection ages of 1-4 million years, suggesting that they were ejected from Mars in just one of two ejection events.”

A photograph of a thin section of one of Cartwright’s Martian shergottite meteorites, with various minerals labelled. The left half of the image is shown in cross polarised light and the right side plane polarised light. By analysing the gases contained within meteorites, scientists can learn about the atmosphere and interior processes of Mars at the time the meteorite was formed and ejected from the planet. Image: Julia Cartwright.

But there is still work to be done to understand the processes that went into forming the different minerals contained within the meteorites, made all the more difficult by contamination by terrestrial processes resulting from the meteorites lying on the Earth’s surface for long periods of time. “Most meteorites will contain some sort of terrestrial component, though this will be determined by the amount of weathering that the meteorite has been subjected to,” she says. “Distinguishing between terrestrial and Martian weathering is very difficult, as similar minerals including clays, sulphates and carbonates are produced in both instances.”

Cartwright comments that a sample-return mission would be priceless regarding any further work on Mars. “Run in tandem to studies on meteorites, the information provided could be just the tip of the ice-berg when it comes to understanding not only the other planets in our Solar System, but our own planet Earth.”

Conway, Cousins and Cartwright were just three of twenty early career scientists presenting their work at the 6th UK Planetary Forum meeting, held at University College London on Monday 3 November. The UK Planetary Forum (UKPF) was founded in 1996 as a representative body of the planetary science community, and aims to promote planetary science in the UK amongst scientists and the public alike. For more information on the UKPF and for full listings of the talks presented, visit the UKPF website
from:http://astronomynow.com/081108EarlycareerplanetaryscientistsexploreMars.html

ESO produces deepest UV image of the Universe

2008-12-02T09:15:00.000-08:00

A new image from the European Southern Observatory (ESO) offers the deepest ground-based ultraviolet image of the Universe ever obtained.

The image contains more than 27 million pixels and reveals a cocktail of brightly coloured and varying shaped galaxies that make up the Chandra Deep Field South (CDF-S). The CDF-S is one of two regions selected as part of the Great Observatories Origins Deep Survey (GOODS), an effort of the worldwide astronomical community that unites the deepest observations from ground- and space-based facilities at all wavelengths from X-ray to radio. Its primary purpose is to provide astronomers with the most sensitive census of the distant Universe to assist in the fundamental study of the formation and evolution of galaxies.

The Chandra Deep Field South observed with ESO’s VIMOS and WFI instruments is the deepest image every taken in the U-band. The image covers a region 14.1 x 21.6 arcminutes. Image: ESO/ Mario Nonino, Piero Rosati and the ESO GOODS Team.

The image combines data obtained from 55 hours of observations with the VIMOS (Visible wide field Imager and Multi-Object Spectrograph) instrument on ESO’s Very Large Telescope (VLT) in the U- and R-bands, as well as data obtained in the B-band with the Wide-Field Imager (WFI) attached to the 2.2 metre Max Planck Gesellschaft/ESO telescope at La Silla. The U-band represents the boundary between visible and ultraviolet light, and in this image is the result of 40 hours of staring at the same region of the sky, resulting in the deepest image ever taken from the ground at this wavelength. At these depths, the sky is almost completely covered by galaxies, each one like our own Milky Way Galaxy, hosting hundreds of billions of stars.

Only a very few stars in this image actually belong to the Milky Way, though, and one can be seen to the left of the second brightest star towards the top of the field of view. It appears as a slightly elongated rainbow because the star moved while the data were being acquired in the different filters over several years.

Such a deep image unveils galaxies a billion times fainter than the unaided eye can see and over a range of colours not directly
observable by the human eye. The CDF-S has already been essential to the discovery of a large number of new galaxies that are so far away that they are seen as they were when the Universe was a youthful two billion years old.

from:http://astronomynow.com/081107ESOproducesdeepestultravioletimageoftheUniverse.html

Fingers and loops revealed in the Crab Nebula

2008-12-02T09:08:00.000-08:00

The Chandra X-ray Observatory has captured the first clear view of the faint boundary of the Crab Nebula’s X-ray emitting pulsar wind nebula.

The Crab Nebula is located about 6,000 light years away in the constellation of Taurus and is powered by a rapidly rotating, highly magnetised neutron star, or pulsar (seen as a white dot near the centre of the image), the remnant of the gravitational collapse of a massive star that met its fate in a supernova explosion.

Chandra has captured a clear view of the faint boundary of the Crab Nebula’s X-ray emitting pulsar wind nebula. Image: NASA/CXC/SAO/F.Seward et al.

The Crab pulsar spins on its axis around 30 times a second, and this rapid rotation, combined with a strong magnetic field, generates an intense electromagnetic field that creates jets of radiation emanating from the poles of the pulsar, and a powerful wind flowing out in the equatorial direction.

As the magnetic pulsar wind slams into the body of the nebula, electrons and positrons (anti-electrons) spiral around the magnetic field lines and radiate away energy. An inner X-ray ring is thought to represent the shock wave that marks the boundary between the surrounding nebula and the flow of particles from the pulsar. Energetic electrons and positrons trapped within the star’s magnetic field move outward from this ring and brighten in an outer ring, producing a glow in X-rays, while many filamentary structures that contain hot gas permeate the nebula itself.

The Crab Nebula in visible light (left) and infrared (right) as seen by Hubble and Spitzer, respectively. The optical image also includes X-ray images (blue colour) from Chandra. The size of the X-ray image is smaller because the higher energy X-ray emitting electrons radiate away their energy more quickly than the lower energy optically emitting electrons as they move. Images: visible: ESA/NASA; Spitzer: NASA/JPL-Caltech/R. Gehrz (University of Minnesota).

The shock front is extremely dynamic, with its shape and position changing rapidly. Further out, fingers and loops of matter and bays that are void of matter all indicate that the magnetic field of the nebula and filaments of cooler matter are controlling the motion of the electrons and positrons. The particles can move rapidly along the magnetic field and travel several light years before radiating away their energy. In contrast, they move much more slowly perpendicular to the magnetic field, and travel only a short distance before losing their energy. The conspicuous dark bays on the lower right and left in the Chandra image are likely due to the effects of a remnant magnetic field from the Crab Nebula’s original progenitor star.

from: http://astronomynow.com/081107FingersandloopsintheCrabNebula.html

Dusty shock waves generate planet ingredients

2008-11-12T19:37:00.000-08:00

Using NASA’s Spitzer Space Telescope, astronomers have shown that shock waves around dusty young stars could be generating the raw materials needed for planet formation.

Shock waves formed by colliding gas and dust in young planet-forming discs may force the creation of raw materials needed for planet growth. Image: ESO.

The findings are also in agreement with local evidence from our own Solar System. Spherical pebbles, called chondrules, found in ancient meteorites that have fallen to Earth are also thought to have been crystallised by shock waves in our Solar System's young planet-forming disc.

from:http://astronomynow.com/081112dustyshockwavesgenerateplanetingredients.html

Sub-millimetre astronomy reveals glowing stellar nurseries

2008-11-12T19:36:00.000-08:00

By using sub-millimetre wavelength astronomy, astronomers have revealed the cold dense clouds of material that are the birth places of new stars.

Colour composite image of RCW120. The submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas. Image: ESO/APEX/DSS2/ SuperCosmos.

from:http://astronomynow.com/081112submillitreastronomyrevealsglowingstellarnurseries.html

Phoenix concludes Martian adventure

2008-11-12T13:39:00.000-08:00

After more than five months on the Martian surface, NASA’s Phoenix Mars Lander has said its farewells to the Earth as the decline in solar power forces the spacecraft to shut down.

Mars Science Laboratory will launch in late 2009 and will be winched down to the Martian surface by a rocket-powered ‘sky-crane’. The landing site has yet to be determined. You can read more about the Mars Science Laboratory in the Astronomy Now 2009 Yearbook, available to buy now
from:http://astronomynow.com/081111PhoenixconcludesMartianadventure.html

Early career planetary scientists explore Mars

2008-11-12T13:37:00.000-08:00

from:http://astronomynow.com/081108EarlycareerplanetaryscientistsexploreMars.html

ESO produces deepest UV image of the Universe

2008-11-09T21:02:00.000-08:00

A new image from the European Southern Observatory (ESO) offers the deepest ground-based ultraviolet image of the Universe ever obtained.

from:http://astronomynow.com/081107ESOproducesdeepestultravioletimageoftheUniverse.html

Fingers and loops revealed in the Crab Nebula

2008-11-09T20:58:00.000-08:00

The Chandra X-ray Observatory has captured the first clear view of the faint boundary of the Crab Nebula’s X-ray emitting pulsar wind nebula.

Chandra has captured a clear view of the faint boundary of the Crab Nebula’s X-ray emitting pulsar wind nebula. Image: NASA/CXC/SAO/F.Seward et al.

from: http://astronomynow.com/081107FingersandloopsintheCrabNebula.html

Phoenix in "precarious times" following power fault

2008-11-06T20:09:00.000-08:00

NASA’s Phoenix Mars Lander tripped into safe mode yesterday in response to a low-power fault, and unexpectedly switched on to the ‘B-Side’ of its redundant electronics, shutting down one of its two batteries in the process.

During safe mode, the lander stops non-critical activities and awaits further instructions from the mission team. Engineers were able to kick start battery charging by sending commands from Earth to the failing lander, but the harsh weather conditions are taking their toll.

NASA's Mars Phoenix Lander is slowly shutting down as winter sets in. The mission, already in its fifth month of a 90 day mission, suffered a fault yesterday due to the
deteriorating weather conditions. Image: NASA/JPL-Calech/University of Arizona.

"This is a precarious time for Phoenix," says Phoenix Project Manager Barry Goldstein. "We're in the bonus round of the extended mission, and we're aware that the end could come at any time. The engineering team is doing all it can to keep the spacecraft alive and collecting science, but at this point survivability depends on some factors out of our control, such as the weather and temperatures on Mars."

Phoenix has recorded the lowest temperatures yet, dipping to -96 degrees Celsius at night and barely rising above -45 degrees Celsius in the day. Dust-storms and water-ice clouds add additional challenges, reducing the amount of sunlight reaching Phoenix’s solar panels, thereby restricting the amount of power the lander can generate. On Tuesday, low temperatures triggered Phoenix’s emergency battery heaters into action, creating another drain on precious power supplies.

"It could be a matter of days, or weeks, before the daily power generated by Phoenix is less than needed to operate the spacecraft," says JPL mission manager Chris Lewicki. "We have only a few options left to reduce the energy usage."

Only this week did mission leaders announce plans to turn off four heaters, one at a time, in an effort to preserve power. The faults experienced yesterday forced the engineers to shut down two heaters instead of one as originally planned, ceasing operations of the robotic arm, robotic arm camera and the thermal and evolved-gas analyser. The second heater served the lander's pyrotechnic initiation unit, which hasn't been used since landing.

Science activities will remain on hold for the rest of the week to allow the spacecraft to recharge and conserve power. It is still hoped that Phoenix will be able to perform meteorological observations at the very least, for some weeks to come.

from:http://www.astronomynow.com/081030phoenixinprecarioustimesfollowingpowerfault.html

Cassini’s imaging trick earned halloween treats from Enceladus

2008-11-06T20:07:00.000-08:00

Following the success of the ‘skeet shoot’ imaging technique employed for the 11 August Enceladus fly-by, Cassini performed the same trick to obtain more high resolution images of the icy satellite this halloween.

Cassini captured more high resolution images of the prominent tiger stripes in the south polar region of Enceladus in a halloween encounter with Saturn’s enigmatic moon. Image: NASA/JPL/Space Science Institute.

While the 9 October fly-by focussed on the geyser-like plumes emanating from the so-called tiger stripes at the moon’s south pole, the halloween fly-by was set on obtaining high resolution images of the terrain from which the jets are erupting. The skeet shoot technique, named after an Olympic shooting event, works by initially pointing Cassini ahead of the moon, and ordering it to track a point in space while it waits for Enceladus to move into the camera’s field of view. Once the targeted region is in the line of fire, the camera shoots images of the high priority target regions in rapid succession.

For the 31 October fly-by, the ground track of the camera's pointing was selected to cut across two tiger stripes, known as sulci. The swath was chosen to pass over three particular segments of the tiger stripes that are known to be local hot spots and which are sites of previously observed eruptions. The results of the fly-by mean that the Cassini team have now observed six of eight jet sources, with the latest fly-by catching sources assigned tags VI and VII in and around the Baghdad sulci, as well as repeating observations of Damascus jet sources II and III. They noted that the region of the active tiger stripes is finely-fractured throughout and littered with icy blocks.

The source region for a jet (assigned the tag VI) was identified in the Baghdad Sulcus region. Image: NASA/JPL/Space Science Institute.

This image was captured at a resolution of just nine metres per pixel, the highest resolution of the halloween encounter. The image shows the south polar terrain in unprecedented detail, revealing fractured terrain littered with icy blocks. Image: NASA/JPL/Space Science Institute.

New mineral points to a wetter Mars

2008-11-05T18:34:00.001-08:00

NASA's Mars Reconnaissance Orbiter (MRO) has observed a new category of minerals spread across large regions of Mars that point towards prolonged periods of water covering the red planet as recently as two billion years ago.

The new mineral, known as opaline silica, was detected on Mars by both the Spirit rover and by the MRO’s CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument earlier in the year, but in the November issue of the journal Geology, the CRISM team provide authoritative evidence for the presence of widespread opal and not some other water-containing (hydrated) mineral.

Opal like minerals have been detected in and around the giant Valles Marineris canyon system, appearing as a light-toned cream colour in this false colour image. The presence of opal in this location suggests water was present on the surface of Mars as recently as two billion years ago. Image: NASA/JPL-Caltech/Univ. of Arizona.

“Finding large outcrops of opal (hydrated silica) on Mars is a great discovery because it shows that the opal detected by the Spirit rover is not a unique occurrence and that this material is apparently quite common in some regions of Mars,” says lead author Dr Ralph Milliken of the Jet Propulsion Laboratory. “Also, the presence of opal and other silica-rich minerals has been predicted to exist on Mars by geochemical models, and now we've finally seen evidence of it on the surface from orbit.”

The hydrated mineral deposits are telltale signs of where and when water was present on ancient Mars, and the MRO observations reveal its presence in long outcrops in the relatively young plains outside of the large Valles Marineris canyon system, as well as some locations near dry river channels. “In some places the opal is found with iron sulfates, which tells us that the deposits may have formed from evaporation of very acidic water,” Milliken tells Astronomy Now. “However, in some locations we only see the opal, so in these places the water might not have been as acidic and may have been more favorable for life. Finding opal in these relatively young deposits tells us that there was liquid water on Mars as recently as 2-2.5 billion years ago, which means that the window for life or habitability on Mars has opened up a bit more than we previously thought.”

Until now, only two major groups of hydrated minerals, phyllosilicates and hydrated sulfates, had been observed by spacecraft orbiting Mars. Clay-like phyllosilicates formed more than 3.5 billion years ago where igneous rock came into prolonged contact with water, and are suited to trapping and preserving organic matter. Hydrated sulfates formed from the evaporation of salty and sometimes acidic water. The newly discovered opaline silicates are the youngest of the three types of hydrated minerals and formed where liquid water altered materials created by volcanic activity or meteorite impact on the Martian surface. The variations in the compositions of the minerals suggest that different types of watery environments created them, showing just how diverse conditions on Mars were in the last few billion years.

The key result of the opal discovery is the implication for the duration of water on Mars, and by association, the ‘extra’ time inferred for life to have taken hold on our neighbouring planet. "What's important is that the longer liquid water existed on Mars, the longer the window during which Mars may have supported life," says Milliken. "The opaline silica deposits would be good places to explore to assess the potential for habitability on Mars, especially in these younger terrains."

NASA’s Mars Science Laboratory will launch in 2009 and although the landing site is yet to be decided, it will be targeting sites most likely to yield signs of past life.

from:http://www.astronomynow.com/081030NewmineralpointstoawetterMars.html

Fireball captured by Canadian cameras

2008-11-05T18:31:00.000-08:00

For the second time this year The University of Western Ontario’s Meteor Group has captured rare footage of a meteor streaking across the sky and possibly falling to the ground.

The meteor was tracked by all seven of Western’s Southern Ontario Meteor Network cameras at 5:28 am on Wednesday 15 October, local time. Western University astronomers suspect that some fraction of the meteor may have fallen to the ground, amounting to a few hundred grams in mass.

All seven cameras of the Meteor Network spotted this meteor streaking across the sky; this image was taken by the Orangeville camera number 6. The lights at the bottom are a moving aircraft. Video of the meteor is available here. Image: University of Western Ontario.

By studying the video footage, the astronomers concluded that the meteor penetrated the Earth’s atmosphere at an altitude of around 37 kilometres whereupon it slowed down considerably. Most meteoroids burn up by the time they hit an altitude of 60-70 kilometres from the ground, but in this case, one or more small meteorites could have made it to the ground intact. The surviving fragments are predicted to lie in a region north of Guelph. The trajectory of the meteor could also be tracked back to its pre-impact orbit, putting it into the typical Earth crossing asteroid type of a stony meteorite. Stony meteorites are composed mostly of silicate minerals and account for around 95 percent of all meteorites seen to fall to Earth.

In March, the same network of all-sky cameras captured a meteor careering towards the Parry Sound area. All-sky cameras consist of a fish eye lens that enables the whole sky to be imaged at once, as the name suggests. A network of three or more cameras allows the meteors to be located via triangulation.

The fireball is suspected to have shed meteorites in a region north of Guelph. Residents are encouraged to contact researchers at Western if they witnessed the event or if they have found fragments of the meteorite. Image: University of Western Ontario.

Just a week before the Canadian accomplishment, a three-metre wide asteroid was seen powering through the skies of northern Sudan as a glowing fireball (read our report here). Meteors streak across the sky on a daily basis, and when the Earth passes through the tail of a comet, we are treated to a meteor shower, such as the Perseids, Orionids, Leonids and Geminids, which offer the best displays. However, it is quite rare that meteoritic material reaches the ground intact, but finding this treasure allows scientists to sample the material of an extraterrestrial body, teaching us about the composition of the residents of our cosmic neighbourhood. The three-metre wide asteroid was a reminder that the Earth is also at risk from potentially devasting impacts without much notice, indeed, that case study was detected less than a day before it was due to penetrate the Earth's atmosphere.

from:http://www.astronomynow.com/081028FireballcapturedbyCanadiancameras.html

Double asteroid belt in Solar System clone

2008-11-05T18:29:00.000-08:00

Spitzer observations have discerned two rocky asteroid belts and an icy outer ring surrounding our Sun’s doppelgänger Epsilon Eridani that could have been shaped by evolving planets.

"This system probably looks a lot like ours did when life first took root on Earth," says lead author of the study Dana Backman of the SETI Institute.

Click to enlarge. Our familiar Solar System compared with the similar layout of Epsilon Eridani's system. Both systems host asteroids (brown), comets (blue) and planets (white dots). Image: NASA/JPL-Caltech.

Epsilon Eridani, visible to the naked eye and located just 10.5 light years away in the constellation Eridanus, is marginally smaller and cooler than our own Sun, but at just 850 million years old is providing insight into how our Solar System evolved. It already shares striking similarities to the formation we are familiar with today, bearing an inner rocky asteroid belt at an equivalent distance from the central sun as our own inner Astroid Belt. An outer rocky belt containing around 20 times as much material also exists in the same position as Uranus.

A third ring of icy material spans a ring from 35 to 100 AU, mimicking the Kuiper belt of our own Solar System but with 100 times more material. But when our own Sun was a spritely 850 million years old, our icy reservoir probably looked much the same as Epsilon Eridani’s, prior to a dramatic clearing out of rocky material during the Heavy Bombardment Era, where material was flung into the inner planets and some even hurled out of the Solar System altogether.

"Epsilon Eridani looks a lot like the young Solar System, so it's
conceivable that it will evolve similarly," says Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics.

Artist impression of the Epsilon Eridani solar system, exhibiting a double asteroid belt and a reservoir of icy cometary material. Image: NASA/JPL-Caltech.

The forming solar system was observed by the Spitzer Space Telescope, and revealed gaps between each of the rings orbiting the central star. Such gaps are best explained by the presence of planets that gravitationally mold the rings and sweep out material as they orbit their central star.

"Planets are the easiest way to explain what we're seeing," says Marengo. Indeed, the astronomers predict that three planets with masses between those of Neptune and Jupiter must be lurking in the system, and a candidate planet near the innermost ring already has been detected by radial velocity studies. A second planet is inferred near the outer asteroid belt at a distance of 20 AU, and a third at about 35 AU near the inner edge of the Kuiper Belt clone.

There is no doubt that the Epsilon Eridani system will be the first on many a planet hunter’s list, and as the resolving power of telescopes increases, astronomers hope to detect terrestrial and even Earth-mass planets orbiting inside the innermost asteroid belt for a true Solar System analogue.

from: http://www.astronomynow.com/081027DoubleasteroidbeltinSolarSystemclone.html

Rebooted Hubble scores a perfect 10

2008-11-05T18:26:00.000-08:00

After numerous glitches with the software onboard Hubble, the world’s favourite space telescope is finally back online, and celebrates by capturing the perfect image.

Arp 147 lies in the constellation of Cetus, over 400 million light years away. This picture was assembled from WFPC2 images taken with three separate filters. The blue, visible-light, and infrared filters are represented by the colours blue, green, and red, respectively. Image: NASA, ESA, and M. Livio (STScI).

The Wide Field Planetary Camera 2 (WFPC2) captured this chance alignment of two galaxies that spell out the number ’10’. Together the interacting galaxies are known as Arp 147. The left-hand galaxy, the ‘1’, appears nearly edge on in our line of sight, and is relatively undisturbed apart from a smooth ring of starlight. The right-hand galaxy, representing the ‘0’, forms a ring of clumpy but intense star formation.

Astronomers speculate that the blue ring was created after the redder looking galaxy plunged through a galaxy on the right. The colliding galaxies would have created a powerful density wave that would have swept out the material into an expanding ring, stimulating star formation. The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.

The galaxy pair was photographed on 27-28 October, demonstrating that Hubble is once again functioning as normal. Later today, NASA representatives will discuss the status of the upcoming repair mission, which was set back to early 2009 following technical problems with Hubble in the days before the mission was originally due to go ahead.

from:http://www.astronomynow.com/081030RebootedHubblescoresaperfect10.html

JCMT sees the dark hearts of bright galaxies

2008-11-05T18:22:00.000-08:00

European astronomers using the James Clark Maxwell Telescope (JCMT) have gained important information on what are known as Ultraluminous Infrared Galaxies (ULIRGs), galaxies with a huge energy output but which are obscured by their massive dust and gas clouds.

Astronomers believe that this class of galaxy was much more common in the younger Universe than it is now, with their impressive energy output attributed to extremely rapid conversion of gas into young, luminous stars and to energetic processes associated with supermassive black holes. Using the HARP receiver on the JCMT, a team of astronomers from Wales, The Netherlands and Germany directly probed the physical conditions in the active inner regions of a number of ULIRGs by penetrating the thick dusty veil surrounding the galaxies and observing the submillimetre radiation.

Spectrum of hydrogen cyanide in a ULIRG obtained with the JCMT and its HARP receiver. The background image shows UGC5101 as observed with the ACS on board the Hubble Space Telescope and shows dust clouds obscuring the most luminous parts of the galaxy which can be seen as a red-brown band. Image: NASA, ESA, the Hubble Heritage STScI/AURA-ESA/Hubble Collaboration, and A. Evans, University of Virginia, Charlottesville/NRAO/Stony Brook University.

"The submillimetre radiation observed by the JCMT can penetrate the dust shroud obscuring the nuclear regions of the ULIRGs, but the spectral lines emitted from these regions are still very faint," says Dr Papadopoulos from Bonn University. "Therefore, we had to use the JCMT and its sensitive HARP receiver for up to 12 hours under very good atmospheric conditions, to detect just a single line in a single galaxy."

Among the molecular fingerprints that the team has observed are spectral lines of warm and dense carbon monoxide (CO) and of the formyl ion (HCO+). However, the most important spectral line detected is hydrogen cyanide (HCN), which originates from warm, dense and highly toxic hydrogen cyanide gas in the most active regions of the ULIRGs. These are the first spectra of this type from a substantial set of ULIRGs, and are surprisingly difficult to detect in many of these extreme objects. When interpreted together with the rest of the data, it becomes obvious that this spectral line probes the most extremely dense gas, the very immediate fuel of the massive star formation in these objects.

"Unlike other spectral lines which probe more remote gaseous regions in these galaxies which may not be actively forming stars, the hydrogen cyanide intensity changes dramatically from galaxy to galaxy," says Paul van der Werf of Leiden University in The Netherlands. "This depends on, and reveals, the intense gravitational tides and their effects on the densest of the gas phases in the centres of the ULIRGs."

The team is continuing its study of ULIRGs with the JCMT by observing the hot dense gas associated with the formation of young stars in these galactic powerhouses. "Even future satellites will not be able to supply us with all the information we need to probe the conditions within these galaxies: the JCMT with its large collecting area provides essential pieces in the puzzle," adds Kate Isaak of Cardiff University.

from: http://www.astronomynow.com/081105JCMTseesthedarkheartsofbrightgalaxies.html

Meteorites’ magnetism holds clues to planet birth

2008-11-05T18:20:00.000-08:00

Magnetic records frozen into the cores of ancient meteorites have provided fresh insight into the planetary forming conditions at the beginning of the Solar System.

Benjamin Weiss of MIT and colleagues studied a group of the oldest known meteorites – angrites, basaltic rocks likely derived from main belt asteroids – to solve a longstanding mystery regarding the way planets form. The key result is that small planetary building blocks around 160 kilometres in diameter were still large enough to melt, separating out into a light crust and a heavier core. This heavy, iron-rich material began to turn over to produce a magnetic dynamo, the traces of which are still preserved in the meteorites that fell to Earth.

iPlanetary building blocks could have been differentiated into mini-planets with core, mantle and crust. Remnant magnetism from these planetesimals has been detected in ancient meteorites that fell to Earth. Image: NASA/JPL-Caltech.

"The magnetism in meteorites has been a longstanding mystery,” says Weiss. Indeed, until relatively recently, it was commonly thought that planetesimals — similar to the asteroids seen in the Solar System today — that came together to build planets were just homogenous, unmelted rocky material, with no large-scale structure. "Now we're realising that many of the things that were forming planets were mini-planets themselves, with crusts and mantles and cores."

The revelation has the potential to change key theories regarding the formation and evolution of planetary bodies in the early Solar System. Specifically, if the smaller bodies were already molten as they slammed together to build up larger planet-sized bodies, that could have implications for how different minerals are distributed in the Earth's crust, mantle and core today.

"In the last five or ten years our understanding of the early history of the Solar System has undergone a sort of mini-revolution, driven by analytical advances in geochemistry,” says Weiss. “In this study we used a geophysical technique to independently test many of these new ideas."

Events in the nascent Solar System took place at a fast rate and the fact that some of the angrite meteorites used in this study formed just three million years after the birth of the Solar System and show signs that their parent body had a magnetic field that was 20 to 40 percent as strong as Earth's today, has serious implications for the development of magnetic fields on planets.

"We are used to thinking of dynamo magnetic fields in rocky bodies as uncommon phenomena today,” says Weiss. “But it may be that short-lived planetesimal dynamos were widespread in the early Solar System." Because the magnetic record preserved in the angrite meteorites extends beyond the expected lifetime of the circumstellar disc, the magnetic fields must have been generated inside the body from which the meteorites were derived, possibly by an early magnetic dynamo in the planetesimal’s rapidly formed metallic core.

The results of the study are published in the 31 October edition of the journal Science.

from: http://www.astronomynow.com/081105meteoritesmagnetismholdscluestoplanetbirth.html

Rare impact craters revealed in Martian polar terrain

2008-11-03T20:01:00.000-08:00

New HiRISE images have revealed two rare sightings of impact craters in the Mars’ northern polar regions.

In the first image, an unusual solitary mound protruding from a depression in a slope in Mars’ north polar layered terrain was brought to the attention of HiRISE scientists. Mars’ layered terrain is made up from stacks of ice and dust several kilometres thick, and is thought to contain much of the planet’s water reservoir. Its formation is believed to be strongly linked to atmospheric processes, and scientists believe the deposits record details of climate changes on the red planet.

This cater surprised scientists because of its location in the north layered terrain where craters are rare, its non-circular shape possibly arising from flowing ice deforming the bowl-shaped cavity, and the mound of bright ice rising out of the crater. The surrounding terrain has lost most of its ice cover, whereas that in the crater could be protected by the crater walls. The image is colour enhanced to show ice as blue/white and the surrounding terrain as yellow. Image: NASA/JPL/University of Arizona.

The new HiRISE image shows an exposed 500 metre thick section of this layering, and part of what could be the remnant of a once buried impact crater. The image reveals a 40 metre high conical mound sticking out of the slope that is made up of polygonal blocks as big as 10 metres across. The blocks are covered with reddish dust, but otherwise resemble ice-rich blocks seen in other images of the north polar layered deposits.

"The mound may be the remnant of a buried impact crater, which is now being exhumed," says planetary scientist Shane Byrne from the Lunar and Planetary Laboratory in Arizona. Impact craters would have been buried by ice as the layered deposits accumulated, with layers wrapping around and infilling the crater. But this is a rare case, since almost no craters exist on the surface of this terrain. "In this case, erosion formed a trough that uncovered one of these structures,” continues Byrne. “For reasons that are poorly understood right now, the ice beneath the site of the crater is more resistant to this erosion, so that as this trough formed, ice beneath the old impact site remained, forming this isolated hill."

This is the crater seen against the vast expanse of the north polar cap. Colours have been enhanced to show dusty regions as red and ice of large grain sizes as blue. A smooth area stretching away from the crater to the upper right of the image may be caused by winds around the crater or by fine-grained ice and frost blowing out of the crater. Image: NASA/JPL/University of Arizona.

In another new HiRISE image a second impact crater 115 metres in diameter is witnessed on the north polar cap itself, where such features are hardly ever observed. The deficit of impact craters in these high northern latitudes suggests that either the north polar cap is only about 100,000 years old or that crater impacts into the ice disappear as the ice relaxes over time.

Since the Mars Reconnaissance Orbiter's HiRISE camera began operations in 2006, it has returned more than 8,200 gigapixel-sized images of the Martian surface that are giving planetary scientists brand new insight into the geology of the red planet

from:http://www.astronomynow.com/081021RareimpactcratersrevealedinMartianpolarterrain.html

The stellar nursery with a massive heart

2008-11-03T19:57:00.002-08:00

A new ESO image reveals the vast stellar nursery of Gum 29, which hosts a small cluster of stars bearing one of the most massive double star systems known to man.

This image was obtained with the Wide Field Imager (WFI) camera attached to the 2.2-metre Max-Planck/ESO telescope through four different filters (B, V, R, and H-alpha), and shows the amazing intricacies of the vast stellar nursery Gum 29. At its centre lies the cluster of young stars Westerlund 2. Image: ESO.

Gum 29, named for it being the 29th entry in astronomer Colin Stanley Gum’s catalogue, is a vast region of ionised hydrogen gas that spans over 200 light years. Known as the H-II region, the hydrogen gas has been stripped of its electrons by the intense breath of hot young stars radiating in its centre. The new image was captured with the Wide Field Imager (WFI) camera attached to the 2.2 metre Max-Planck telescope at the European Southern Observatory (ESO)’s La Silla site in Chile.

A young and little-known star cluster – Westerlund 2 – is embedded within the belly of Gum 29 at a distance of 26,000 light years from Earth, corresponding to a location within the outer edge of the Carina spiral arm of our Milky Way Galaxy. It is thought to be just one or two million years old. Two stars in the bottom right of Westerlund 2 form a double star system of huge proportions at 82 and 83 times the mass of our Sun respectively, and rotating around each other in approximately 3.7 days. They are amongst the most massive stars known to astronomers.

Marked in the image is a double stellar system in the Westerlund 2 cluster. The two stars have masses of 82 and 83 times that of our Sun and are amongst the most massive stars known to astronomers. Image: ESO.

Intense scrutiny of this pair has also revealed their identity as Wolf-Rayet stars, massive stars that are expelling huge quantities of material as they near the end of their lives. Observations made in X-rays have subsequently shown that streams of material from each star continually collide, creating a blaze of X-ray radiation.

COROT sees sunquakes in other stars

2008-11-03T19:57:00.001-08:00

The CNES/ESA Earth orbiting COROT satellite has applied the technique of seismology to the study of stellar interiors, probing the interiors of three stars beyond our own Sun for the first time.

COROT can detect ‘starquakes’, acoustic waves generated deep within a star that ripple across the star’s surface, altering its brightness. By studying these variations, a star’s mass, age and structure can be determined. Image: CNES.

Like the propagation of seismic waves on Earth providing information about our planet's interior, sound waves travelling throughout the Sun and other stars carry information about what is happening below the surface. The study of these waves propagating through a star is known as helioseismology, and has already been used to generate complex models of the interior conditions on our Sun, showing that different layers of our home star rotate at different speeds to generate the Sun’s magnetic field, and that jet streams of plasma run thousands of kilometres below the surface.

Oscillations of the Sun’s surface can also be tracked by direct observations and related to interior processes by the tool of helioseismology. Similar oscillations can be observed on other stars by watching for variations in the light emitted by the star as the surface wobbles, revealing both the internal structure of the star and the way energy is transported from the core to the surface.

"Other techniques to estimate stellar oscillations have been used from the ground, but they are limited in what they can do," says Malcolm Fridlund, ESA Project Scientist for COROT at ESA's European Space Research and Technology Centre (ESTEC). "Adverse weather conditions, plus the fact that you cannot observe stars during daytime, oblige ground astronomers to interrupt their observations.”

COROT consists of a 27 centimetre telescope and was launched in December 2006. Image: CNES/D. Ducros.

The COROT satellite allows uninterrupted viewing from afar, and with high sensitivity instruments such as a 4-CCD camera capable of recording tiny variations of light intensity emitted from a star, COROT offers a new view of our stellar neighbourhood. In the new study, three Sun-like stars were scrutinized by COROT: HD499933, HD181420 and HD181906, revealing 'sunquakes' rumbling inside their interiors.

"The fact that COROT succeeded in probing the interior of Sun-like stars with direct measurements for the first time is a huge leap in understanding stars in general", says Fridlund. "In addition, this will help us to understand, by comparison, our own Sun even better."

COROT was launched at the end of 2006 and was designed as both a planet hunter and star surveyor, having clocked up six exoplanets to date with the aim of surveying around 120,000 stars for exoplanets, and over a hundred stars for stellar seismology studies.

from:http://www.astronomynow.com/081024COROTseessunquakesinotherstars.html

2008-06-06T02:43:00.000-07:00

The Milky Way is a large place, and getting all the stars together, even from just the inner galaxy, for a family photo requires a big canvas. The imaging team from the Spitzer Space Telescope today unveiled the largest, highest resolution infrared picture ever taken of the Milky Way. The photo spans 55 meters (180 feet), and takes up almost one entire wall in the huge exhibit hall here at the AAS meeting in St. Louis (above.) The image is made of 800,000 snapshots taken by Spitzer, amassing 39,000 X 6000 pixels, and shows an area of sky 120 degrees longitude by 2 degrees latitude. It provides 100 times better angular resolution than any previous survey and is 100 times more sensitive. There's also an online version….

This "chops" up the image into five strips, and certainly isn't as impressive as the 55 meter version! However, there's another, more spectacular way to view this spectacular image. The GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) Image Viewer provides a great way to view and browse this image. The viewer boasts the following tagline: "One spacecraft, 5 infrared bands, 800,000 images, 4 billion pixels of data." It lets you scan the image with both the IRAC (Infrared Array Camera) on Spitzer, or the MIPS (Multiband Imaging Photometer.)

2008-06-06T02:37:00.000-07:00

If you were stuck inside your house, you'd never know what it looks like from the outside. That's the situation with the Milky Way. We're inside it, so we don't really know what its structure looks like. There are other examples of grand spirals that we can see, but this is like seeing other houses outside your window; you just can't be sure. Astronomers have developed a detailed map of the Milky Way, and realized that they were giving our home galaxy too many arms; it's only got 2, and not 4 like astronomers originally thought.

The new revelation was made possible thanks to NASA's Spitzer Space Telescope, which sees in the infrared spectrum, and can peer though the gas and dust that obscures the plane of the Milky Way.

Previous maps of the Milky Way were first developed in the 1950s, when astronomers used radio telescopes to trace out the spiral arms of our home galaxy. They focused on gas clouds, and revealed what they thought were 4 major star-forming arms: Norma, Scutum-Centaurus, Sagittarius and Perseus.

We live in minor arm called the Orion Arm, or the Orion Spur, located between the Sagittarius and Perseus Arms.

And then in 2005, astronomers used infrared telescopes to pierce through the clouds of gas and dust to see that the central bar in the middle of the Milky Way extends much further than previously believed.

In a new survey by Spitzer, astronomers merged together 800,000 photographs containing over 110 million stars. Software counted up the number of stars and measured their density.

As expected, astronomers found an increase in density in stars towards the Scutum-Centaurus Arm, but no increase towards the Sagittarius and Norma arms. The Perseus arm wraps around the outer portion of our galaxy and can't be seen in the Spitzer images.

This helps make the case that the Milky Way only has two spiral arms; a commonly seen situation where a galaxy has a long central bar.

Japan space lab anchored to ISS

2008-06-06T02:35:00.000-07:00

A team of astronauts has attached a $1bn (£500m) Japanese laboratory to the International Space Station (ISS).

The 15-tonne Kibo lab was delivered by the shuttle Discovery. It will be the station's biggest room, for the study of biomedicine and material sciences.

Astronauts Akihiko Hoshide and Karen Nyberg manoeuvred Kibo into place, using the space station's robotic arm.

The lab was anchored after two crew members had made preparations during a spacewalk lasting more than six hours.

Discovery docked at the ISS on Monday after a two-day voyage.

As well as the Japanese laboratory, the shuttle has also brought a new pump for the station's toilet, which broke nearly two weeks ago.

The failure has resulted in the resident crew on the ISS having to perform manual flushes several times a day.

The lab was moved into place using a mechanical arm

The Kibo Japanese Pressurised Module (JPM) is the size of a bus and joins the US Destiny lab and the European Columbus lab which are already attached to the platform.

Kibo is so big it could not be fitted inside a single shuttle and is being assembled in three parts. A logistics module went up on the previous shuttle flight; an exposed "terrace" on which experiments can be done outside of the station will launch in 2009.

The logistics module will be moved from its current docking position to a berthing point on the JPM later in Discovery's mission. All of its contents - experimental racks and equipment - can then be moved inside the 11.2m-long cylinder to get the module ready for science.

Kibo experiments will make use of the weightless conditions experienced in orbit.

Being able to see how biological, chemical and physical systems behave in the absence of a strong gravity field will help researchers better understand how the human body works and aid their search for materials that display useful new properties.

The Discovery flight has also delivered Canadian-born astronaut Greg Chamitoff, who will replace flight engineer Garrett Reisman as a station resident for the next six months.

Discovery also carried up a VIP - the space ranger Buzz Lightyear.

The 30cm-tall (12in) action figure, made famous in the Disney/Pixar Toy Story movies, went into orbit as part of an educational programme.

Nine further shuttle flights are required to complete the ISS before the orbiter fleet is retired in 2010.

Discovery's return to Earth is scheduled for 14 June.
Source: http://news.bbc.co.uk/1/hi/sci/tech/7432466.stm

So, What Do Astronomers Do With A 55 Meter-Long Image?

2008-06-06T02:33:00.000-07:00

The new 55-meter image that was unveiled today is impressive, but does it hold any scientific value? A resounding yes to that question came from astronomers who helped work on this project, and given the standing room only for the oral presentation of the scientific research going into this image, plenty of other astronomers are interested in the discoveries from Spitzer's five-year effort of gathering infrared data of our home galaxy. "This is a legacy science project," said Barbara Whitney of the Space Science Institute, "that shows star formation as never seen before on both the large and small scale. Most of these star forming regions are being seen for the first time."

"This is the highest-resolution, largest, most sensitive infrared picture ever taken of our Milky Way," said Sean Carey of NASA's Spitzer Science Center. "Where previous surveys saw a single source of light, we now see a cluster of stars. With this data, we can learn how massive stars form, map galactic spiral arms and make a better estimate of our galaxy's star-formation rate," Carey explained.

From our vantage point on Earth, we see the Milky Way as a blurry, narrow band of light that stretches across the sky. In the visible, we only see about 5% of what's actually out there. But with Spitzer's dust-piercing infrared eyes, astronomers have peered 60,000 light-years away into this fuzzy band, called the galactic plane, and saw all the way to the other side of the galaxy.

The result is a cosmic tapestry depicting an epic coming-of-age tale for stars.

While evolved stars are seen as blue, the star forming regions are seen as green. The regions where young stars reside are revealed as "bubbles," or curved ridges in the green clouds. These bubbles are carved by the winds from the outflow of dust from the young stellar objects. The starlets appear as yellow and red dots, and wisps of red are dust particles.

"With these Spitzer data, we've been able to catalogue more than 100 million stars," said Edward Churchwell of the University of Wisconsin, at Madison.

"This picture shows us that our Milky Way galaxy is a crowded and dynamic place. We have a lot to learn. I've definitely found a lot of things in this map that I didn't expect to see," said Carey.

Source : http://www.universetoday.com/2008/06/03/so-what-do-astronomers-do-with-a-55-meter-long-image/

Milky Way Mapping Project Finds Surprisingly Slow Stars

2008-06-06T02:28:00.000-07:00

Saint Louis, MO - On Earth, making a map is as easy as taking aerial photographs or surveying a patch of land on foot. In contrast, mapping the Milky Way galaxy is a tremendous challenge. The distances are too large to travel, making bird's-eye views or direct surveys impossible. Instead, astronomers must make do with the view from Earth, which is embedded in the galaxy itself. It's like a sardine, 400 miles offshore, trying to figure out the size and shape of the Pacific Ocean. For astronomers, the edge-on view and obscuring dust make it difficult to map anything farther than about 6,000 light-years, at least using visible light.

Now, ultra-precise radio measurements using the National Science Foundation's Very Long Baseline Array (VLBA) have given astronomers their first good look at the structure of the Milky Way and the motions of its young stars. Already, the measurements have turned up a big surprise: the mapped stars are orbiting slower than expected and moving in looping, oval paths rather than circling the galactic center.

"Almost all of our targets seem to have been accelerated opposite the direction of the galaxy's rotation," said Smithsonian astronomer Mark Reid (Harvard-Smithsonian Center for Astrophysics.) Reid discussed his findings today in a press conference at the 212th American Astronomical Society meeting.

Reid speculated that the accelerating force came from the galaxy's spiral arms. The Milky Way's spiral pattern comes from a phenomenon called a density wave, which acts like an astronomical traffic jam. Just as cars stuck behind a slow-moving truck catch up to each other and slow down, gas clouds approaching a spiral arm catch up to each other and slow down. They also compress, birthing the hot, young stars that Reid studied.

The slowing motion and resulting loss of angular momentum shift the stars' orbits from circular to elliptical. Since previous efforts to map the Milky Way assumed that stars orbit in circles, the resulting maps have intrinsic errors.

Reid used the VLBA to measure the parallax, or apparent shift in position on the sky as the Earth orbits the Sun, for masers in about a dozen star-forming regions. He then applied basic geometry to calculate highly accurate distances to each region. He also was able to observe the motion of each maser in the plane of the sky. Combining those data with motions along the line of sight yielded the true, 3-d motion of each target through space.

The VLBA's capabilities were crucial to this project. "The VLBA runs so smoothly that it makes my work easy," Reid said.

He added that the accuracy of the VLBA exceeds that of any other mapping instrument. "The previous gold standard, the Hipparcos satellite, could measure positions of stars to an accuracy of 1 milli-arcsecond. We're doing 100 times better with the VLBA."

Reid and his colleagues in Germany, Italy, and China plan to continue this mapping project by racking up several dozen more targets in the years to come. Ultimately, this work will help answer basic questions about the structure of the Milky Way.

"We don't even know how many spiral arms the Milky Way has-two or four," Reid explained.

Reid also looks forward to the launch of Hipparcos' successor, the European Space Agency's spacecraft Gaia. It will map the positions of up to 1 billion stars located as far as 30,000 light-years from Earth.

"Right now, our map of the Milky Way still has large areas marked 'Here there be dragons.' Ten years from now, those areas will be filled in," Reid said.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu

Source: http://www.cfa.harvard.edu/press/2008/pr200812.html

Toilet is Fixed and Kibo is Switched On - A Great Day Aboard the ISS (Video)

2008-06-06T02:24:00.001-07:00

It has been a very good day for the crew on board the International Space Station. Not only has the brand new Japanese Kibo science laboratory been activated, much to the crew's relief, the faulty toilet has also been fixed. Russian flight engineer Oleg Kononenko was able to replace the broken urine collection pump in a 2 hour repair job yesterday (Wednesday) and specialists in Moscow checked his work to verify it was working fine. Although this may sound like a bit of minor news, it was make-or-break time for the ISS as if the repair was unsuccessful, this may have seriously hindered the manned presence on the station (and besides, we haven't even had time to play with Kibo yet!)…

It looks like the replacement part for the ISS toilet is working as it should after it was delivered by Discovery on June 2nd. Cosmonaut Oleg Kononenko successfully carried out the technical plumbing job and all seems to be flushing as it should. Although a toilet fix in space may not seem like a critical factor, 10-days without a functioning toilet on board the ISS have been difficult for the crew. Until now, all crew members have had to make do with the single toilet facility on board the Russian Soyuz vessel currently docked at the station. It is fortunate the break-down happened when it did, with enough time for the Russian space agency to send replacement parts to the US in time for Space Shuttle Discovery's launch last weekend.

As Kononenko worked on the unglamorous task of fixing the toilet, the other astronauts were working on installing Kibo. All connections from Kibo to the station had to be made, including water supply, power and air, and today it was pressurized and powered up. The new Kibo science laboratory that was attached to the station on Tuesday following a six-hour spacewalk by two astronauts to prepare for its installation. Everything is looking good and the crew hope to open the hatch, float in and explore the station's brand new science module some time today.

View the Reuters video report about the plumbing trouble on the ISS »

Source: USA Today

Highest Resolution View Ever From Mars Comes From Phoenix Lander

2008-06-06T02:21:00.000-07:00

June 5, 2008 -- A microscope on NASA's Mars Phoenix Lander has taken images of dust and sand particles with the greatest resolution ever returned from another planet.

The mission's Optical Microscope observed particles that had fallen onto an exposed surface, revealing grains as small as one-tenth the diameter of a human hair.

"We have images showing the diversity of mineralogy on Mars at a scale that is unprecedented in planetary exploration," said Michael Hecht of NASA's Jet Propulsion Laboratory, Pasadena. He is the lead scientist for Phoenix's Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instrument suite.

The Phoenix mission is led by Peter Smith at The University of Arizona with project management at JPL and development partnership at Lockheed Martin, Denver.

Meanwhile, Phoenix received commands Thursday to collect its first soil sample to be delivered to a laboratory instrument on the lander deck. Commands for that same activity sent on Wednesday did not reach Phoenix because the orbiter intended for relaying the transmission, NASA's Mars Odyssey, had put itself into a safe standby mode shortly before the commands would have reached Odyssey.

On Wednesday, the lander completed a back-up plan of activities that had been sent previously, reported JPL's Chris Lewicki, mission manager for Phoenix surface operations on the lander's 11th Martian day. That plan included weather monitoring and additional imaging for a high-resolution color panorama of the site.

The Optical Microscope images were taken June 3 of particles that had collected on a sticky surface exposed during the Phoenix landing and for five days after landing. "It's a first quick look," Hecht said. "This experiment was partly an insurance policy for something to observe with the microscope before getting a soil sample delivered by the arm, and partly a characterization of the Optical Microscope. All the tools are working well."

Some of the particles might have come from inside the spacecraft during the forceful events of landing, but many match expectations for Martian particles. "We will be using future observations of soil samples delivered by the Robotic Arm to confirm whether the types of particles in this dustfall sample are also seen in samples we can be certain are Martian in origin," Hecht said.

The particles show a range of shapes and colors.

"You can see the amount of variety there is in what appears otherwise to be just reddish brown soil," said Tom Pike, Phoenix science team member from Imperial College London. He noted that one translucent particle resembles a grain of salt, but that it is too early to say for sure.

Thursday's commands were relayed to Phoenix via NASA's Mars Reconnaissance Orbiter. The relay radio on that orbiter has been working well in recent days, after intermittently turning itself off last week. Phoenix will continue to do relays via Mars Reconnaissance Orbiter until Odyssey returns to full functioning, and then Phoenix will use both orbiters.

"We are currently bringing the Odyssey spacecraft back into nominal operations, and we will resume relay service with Odyssey in the next day or two," said JPL's Chad Edwards, chief telecommunications engineer for the JPL Mars Exploration Program.

"We think Odyssey went into safe mode because of a single event that affected computer memory," Edwards said. "Yesterday's safe mode event appears to be very similar to events that have caused Odyssey to go into safe mode two or three times earlier during its long operation around Mars." Odyssey has been orbiting Mars since 2001.

International contributions to the Phoenix Mars mission come from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.

Click Here for images shown during this press conference

Source From: http://phoenix.lpl.arizona.edu/06_05_pr.php

Launchpad Damaged During Saturday's Shuttle Launch

2008-06-02T02:17:00.000-07:00

Debris falls into the water during Discovery's launch on Saturday. Image from CBS Space Place.

The launchpad at Kennedy Space Center was damaged during Saturday's space shuttle launch. Pictures taken during Discovery's launch show debris raining down into the waterway just behind launchpad 39A. Additional images show debris that appears to be broken concrete littering a nearby road as well as damaged and buckled concrete on one side of the launchpad. CBS News' Bill Harwood reported that the damage to the pad occured on the north side of the "flame trench" wall. The trench is used to divert exhaust from the shuttle's solid rocket boosters.

The damage is "unusual," Harwood quoted NASA spokesman Bill Johnson, who verified the damage was serious and tomorrow (Monday) a full report on the incident will be issued. Harwood also reported that a NASA manager said part of the pad's base was repaired following a previous launch, but possibly something was either missed or not repaired correctly.

The debris appears to come from the lauchpad itself, and not the shuttle. However, the astronauts on board Discovery have not yet been able to conduct the usual inspection of the shuttle nose cap and wing leading edge panels because the 50-foot-long boom equipped with laser scanners and high-resolution cameras was unable to fit into the shuttle's payload bay due to the large size of the Japanese Kibo laboratory that Discovery is bringing to the International Space Station. The last shuttle crew left the orbiter boom sensor system at the ISS, and the crew of Discovery will retrieve it while docked to the station. ISS crew members will take high resolution pictures of the shuttle as it approaches the station on Monday.

Both launchpads at KSC, 39A and 39B were originally built for the Apollo spacecraft/Saturn rockets and were modified for the space shuttles. During launches the pads must withstand both high heat and extreme pressure.

Original News Source: CBS Space Place

It Really Looks Like Ice on Mars

2008-06-02T02:16:00.000-07:00

Take a look at this image sent back from the Phoenix lander. On Friday, Phoenix scientist Ray Arvidson said there may be ice directly under the Phoenix lander, exposed in the blast zone by the retrorockets used for Phoenix's soft landing. Friday's image showed a small portion of the exposed area that looks brighter and smoother than the surrounding soil. On Saturday, Sol 5 for Phoenix on Mars, a new image shows a greater portion of the area under the lander. Scientists say the abundance of excavated smooth and level surfaces adds evidence to a hypothesis that the underlying material is an ice table covered by a thin blanket of soil. This is just what the Phoenix mission was hoping to find, and how incredible to land directly over your goal.

The bright-looking surface material in the center, where the image is partly overexposed, may not be inherently brighter than the foreground material in shadow. But the scientists are calling this area "Holy Cow." Reportedly (via Emily at the Planetary Society) that's exactly the phrase exclaimed when this image was returned. More pictures of this feature will be imaged using different exposures in an effort to determine if this really is ice.

The other interesting aspect of this image is that the retrorocket nozzles are visible right at the top of the image.

We'll keep you posted when there's more information and data available on the area under the lander.

Sources: Phoenix, Planetary Blog

Harvesting Solar Power from Space

2008-06-02T02:15:00.000-07:00

In a new report, the viability of sending solar panels into space to collect a vast quantity of uninterrupted energy has been re-investigated. Although the idea has been around since the 1970's, space solar power has always been viewed as prohibitively expensive. In the current energy climate down here on Earth with spiralling oil prices and a massive push toward green energy sources, sending massive solar arrays into geosynchronous orbit doesn't seem like such a strange (or expensive) idea. There are many obstacles in the way of this plan, but the international community is becoming more interested, and whoever is first to set up an orbital array will have a flexible and unlimited energy resource…

It sounds like the perfect plan: build a vast array of solar panels in space. This avoids many of the practical problems we have when building them on Earth such as land availability, poor light conditions and night time, but sending a sunlight farm into space will be expensive to set up. In the 1970's a plan was drawn up by NASA for the possibility of orbital sunlight "harvesting", but it was deemed too expensive with a hefty price tag of at least $1 trillion. There was no country in the world that could commit to such a plan. But as we slowly approach an era of cheaper space travel, this cost has been slashed, and the orbital solar energy case file has been re-opened. Surprisingly, it isn't the most developed nations in the world that are pushing for this ultimate renewable energy source. India and China, with their ballooning populations are reaching a critical point for energy consumption and they are beginning to realise their energy crisis may be answered by pushing into space.

"A single kilometer-wide band of geosynchronous Earth orbit experiences enough solar flux in one year to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today." - Pentagon's National Security Space Office 2007 report.

So how could this plan work? Construction will clearly be the biggest expense, but the nation who leads the way in solar power satellites will bolster their economy for decades through energy trading. The energy collected by highly efficient solar panels could be beamed down to Earth (although it is not clear from the source what technology will go into "beaming" energy to Earth) where it is fed into the national grid of the country maintaining the system. Ground based receivers would distribute gigawatts of energy from the uninterrupted orbital supply. This will have obvious implications for the future high demand for electricity in the huge nations in Asia and will wean the international community off carbon-rich non-renewable resources such as oil and coal. There is also the benefit of the flexible nature of this system being able to supply emergency energy to disaster (and war-) zones.

"It will take a great deal of effort, a great deal of thought and unfortunately a great deal of money, but it is certainly possible." - Jeff Keuter, president of the George C. Marshall Institute, a Washington-based research organization.

The most optimistic time frame for a fully operational space-based sunlight collection satellite would be 2020, but that is if we started work now. Indeed some research is being done (Japan is investing millions of dollars into a potential prototype to be put into space in the near future), but this is a far cry from planning to get full-scale operations underway in a little over a decade…

Source: CNN International

Get Ready for High-Energy GLAST

2008-06-02T02:11:00.000-07:00

It's not hard to grab someone's attention when you mention the words "super massive black holes," "gamma ray bursts," "cosmic rays," and " dark matter." NASA's next space telescope will attempt to grab data about some of these high-energy objects in our universe to help us understand their mysteries. GLAST, the Gamma-ray Large Area Space Telescope will use its instruments to study those objects that generate gamma-ray radiation, the most energetic form of radiation we know of, billions of times more energetic than the type of light visible to our eyes. Liftoff for GLAST is set for Thursday, June 5, and the launch window extends from 11:45 a.m. to 1:40 p.m. EDT.

GLAST will reside in a circular, low Earth orbit of about 560 km ( 350 miles ). This orbit was chosen to minimize the effects of charged particles that surround Earth, and which would create additional unwanted background signals in the detectors. At that altitude, the observatory will circle Earth every 90 minutes. In sky-survey mode, GLAST will be able to view the entire sky in just two orbits, or about 3 hours.

The instruments on the GLAST mission are the Large Area Telescope (LAT) and the GLAST Burst Monitor. Lat has a tracker for gamma-ray detection and direction measurement, and can also measure the energies of the rays. The GBM will have two types of scintillators mounted on the sides of the spacecraft to detect electromagnetic waves.

Phil over at Bad Astronomy has a couple of very nice (and fun) videos with info about GLAST (one starring Phil himself), but these are the major goals of GLAST:

• Explore the most extreme environments in the Universe, where nature harnesses energies far beyond anything possible on Earth.
• Search for signs of new laws of physics and what composes the mysterious Dark Matter.
• Explain how black holes accelerate immense jets of material to nearly light speed.
• Help crack the mysteries of the stupendously powerful explosions known as gamma-ray bursts.
• Answer long-standing questions across a broad range of topics, including solar flares, pulsars and the origin of cosmic rays.

GLAST should provide some very interesting data about these spectacular and remarkable objects in our universe, and will create a full-sky map of gamma radiation.

Kapla GLAST!

Source: GLAST site

Historical divergence

2008-02-02T22:22:00.000-08:00

From ancient times until the 17th century, astrologers constantly desired more accurate astronomical tables, and for this reason, they instigated and even funded many important developments in astronomy. The role of astrology as an important motivation for astronomical research diminished as the works of Galileo and others solved the problems in celestial mechanics that were of interest to astrologers, and as belief in astrological influences or correlations became extinct among astronomers. The needs of modern navigation and physics became more important motivators for astronomical research.

Astrology and astronomy began to take divergent paths during the rise of the rational and the scientific method in the Western World. The science of astronomy as we know it today (mathematical, mechanical, empirical) is of relatively recent origin. This discipline became separated from and generally antagonistic towards astrology only beginning around the time of the "Great Astronomers" -- Galileo, Kepler, Copernicus, Brahe, etc. (though they were all still astrologers as well as astronomers). This period is defined as the beginning of the scientific revolution, leading on into The Age of Enlightenment, sometimes referred to as The Age of Reason -- as stated, the two fields diverged completely in the West between approximately 1750-1800.

It is a commonly held belief among astrologers that Isaac Newton had an interest in astrology. However, Newton's writings fail to mention the subject and the handful of books in his possession that contained references to astrology were primarily concerned with other subjects such as the writings of Hermes Trismegistus (and mentioned astrology only in passing.) In an interview with John Conduitt, Newton said that as a young student, he had read a book on astrology, and was "soon convinced of the vanity & emptiness of the pretended science of Judicial astrology" (D.T. Whiteside, M.A. Hoskin & A. Prag (eds.), The Mathematical Papers of Isaac Newton (Cambridge University Press, Cambridge, 1967), vol. 1, pp. 15-19).

Perhaps the words astrolomer/astrolomy or astronoger/astronogy would be sufficient to describe the aforementioned dual roles of just about every person seriously studying (astronomy) and interpreting (astrology) the sky from antiquity until about 1750-1800. In Medieval Europe the word Astronomia was often used to encompass both disciplines as this included the study of astronomy and astrology jointly and without a real distinction; this was one of the original Seven Liberal Arts.

Astrology and astronomy stayed together for a very long time - the funding from astrology supported major astronomical research, which was in turn used to make more and more accurate ephemerides for use in astrology. As the funding and technology progressively increased, this inexorably lead to greater and greater discoveries that eventually drove the two apart.

Most of the very early, ancient astronomers/astrologers up until about 1750-1800 were simultaneously employed as astrologers for the powerful and the wealthy; many Kings and Queens employed court astrologers to aid them in the running of their kingdom, and this is where most of the money that was used to fund much need astronomical research came from.

University medical students were taught astronomy/astrology for use during their practice as physicians; they needed to know how to observe (astronomically) in order to be able to interpret (astrologically) and treat the illness. (See Medical astrology.)

More often than not it was only because of the prospect of getting better and more accurate astrological predictions that the rich (Royalty) were willing to invest in the very expensive projects of creating observatories and funding constant astronomical observations (see Tycho Brahe), which were very time consuming and just didn't seem quite as interesting as the 'mystical' art of astrology.

Distinguishing characteristics

2008-02-02T22:18:00.001-08:00

* The primary goal of astronomy is to understand the physics of the universe. Astrologers use astronomical calculations for the positions of celestial bodies along the ecliptic and attempt to correlate celestial events (astrological aspects, sign positions) with earthly events and human affairs. Astronomers consistently use the scientific method, naturalistic presuppositions and abstract mathematical reasoning to investigate or explain phenomena in the universe. Astrologers use mystical/religious reasoning as well as traditional folklore, symbolism and superstition blended with mathematical predictions to explain phenomena in the universe. The scientific method is not consistently used by astrologers.

* Astrologers practice their discipline geocentricically [12] and they consider the universe to be harmonious, changeless and static, while astronomers believe that the universe is without a center and is dynamic, expanding outward. [13]

* Astrologers are deterministic; that is, they believe that everything in the universe is orderly, predictable and predetermined, that nothing happens at random.[14] Astronomers, on the contrary, believe that both order and randomness simultaneously exist in the universe; that is, astronomers believe the universe is not entirely orderly, predictable and predetermined, that randomness does in fact exist in the universe to at least some extent. Random cosmic collisions and other random phenomena occur everywhere in the universe.

* Both astrologers and astronomers see Earth as being an integral part of the universe, that Earth and the universe are interconnected as one cosmos (not as being separate and distinct from each other). However, astrologers philosophically and mystically portray the cosmos as having a supernatural, metaphysical and divine essence that actively influences world events and the personal lives of people.[15]. However, astronomers teach that nothing in the universe is divine or supernatural, and that nothing in outer space directly manipulates world events or the personal lives of people in supernatural or divine ways. Astronomers believe that, because the Earth is an integral part of the universe, celestial objects are just as humbly natural as terrestrial objects, being composed of exactly the same substances, and controlled by exactly the same forces, as objects on Earth. The substances iron, hydrogen, sulfur, carbon, nitrogen and oxygen, as well as the fundamental interactions of gravity, electromagnetism, weak force and strong force, are just as prevalent within the stars and planets as they are on Earth.

* Astronomers refers to star patterns as "constellations" and "asterisms", while astrologers refer to star patterns as "signs". Contemporary astronomers, who are academic instead of mystical or superstitious, have little use for the constellations, accepting them only as "regions" or "provinces" of the sky for scientific observation and academic study, instead of as real pictures in the sky. Unlike the mystical and superstitious astrologers, who believe and teach that pictures truly exist among the constellations and have supernatural or divine influences on people, today’s academic mainstream astronomers believe and teach that pictures do not truly exist among the constellations. Instead, today’s academic mainstream astronomers believe and teach that people and cultures throughout history only imagined pictures among the constellations and composed myths and stories about what they imagined in the sky, and that such mere "pictures of the imagination" have no supernatural or divine influences on people whatsoever. Today’s academic mainstream astronomers believe and teach that a constellation is nothing more than a group of stars in a specific region of the sky, and that any person or culture, at any time or place, can imagine whatever picture they wish among a particular group of stars, as history proves via the many ancient and modern cultures, each culture having its own unique star lore.

* Astrologers and astronomers differ in their approach to concepts such as constellations. Astronomers recognize a thirteenth constellation, Ophiuchus, in addition to the twelve astrologers recognize. Astrologers traditionally omit Ophiuchus from their zodiacal signs, preferring twelve due to a long-standing conceptual system in which twelve signs are vital. In addition, due to the 26,000 year precession cycle of Earth on its axis of rotation, the constellations along the ecliptic are no longer positioned the same as they were during Aristotle and Ptolemy's day (when the current astrological system was first established). The Sun, for example, no longer enters Aries on the vernal equinox, instead, it now enters Pisces during that time, making Pisces the true contemporary first sign of the zodiac instead of Aries. Precession only affects the astrological traditions employing the tropical zodiac, such as Western astrology, however. Indian astrology, which uses the sidereal zodiac, uses modern star positions.

Overview Astrology

2008-02-02T22:18:00.000-08:00

Historically, most cultures have not made a clear distinction between the two disciplines, lumping them both together as one. In ancient Babylonia, famed for its astrology, there were not separate roles for the astronomer as predictor of celestial phenomena, and the astrologer as their interpreter; both functions were performed by the same person. This overlap does not mean that astrology and astronomy were always regarded as one and the same. In ancient Greece, presocratic thinkers such as Anaximander, Xenophanes, Anaximenes, and Heraclides speculated about the nature and substance of the stars and planets. Astronomers such as Eudoxus (contemporary with Plato) observed planetary motions and cycles, and created a geocentric cosmological model that would be accepted by Aristotle -- this model generally lasted until Ptolemy, who added epicycles to explain certain motions. The Platonic school promoted the study of astronomy as a part of philosophy because the motions of the heavens demonstrate an orderly and harmonious cosmos. In the third century B.C.E., Babylonian astrology began to make its presence felt in Greece. Astrology was criticized by Hellenistic philosophers such as the Academic Skeptic Carneades and Middle Stoic Panaetius. However, the notions of the Great Year (when all the planets complete a full cycle and return to their relative positions) and eternal recurrence were Stoic doctrines that made divination and fatalism possible.

While the Greek words astrologia and astronomia were often used interchangeably, they were conceptually not the same. Both words more often than not referred to astronomy. The words for astrology proper, were more typically apotelesma and katarkhê.[citation needed]

The earliest to differentiate between the terms astronomy and astrology was Isidore of Seville in the 7th century, while the earliest semantic distinction between astronomy and astrology was given by the Persian astronomer and astrologer Abu Rayhan al-Biruni circa 1000.[11]

Astrology was widely accepted in the Middle Ages as astrological texts from Hellenistic and Arabic astrologers were translated into Latin. In the late Middle Ages, its acceptance or rejection often depended on its reception in the royal courts of Europe. Not until the time of Francis Bacon was astrology rejected as a part of scholastic metaphysics rather than empirical observation. A more definitive split between astrology and astronomy the West took place gradually in the seventeenth and eighteenth centuries, when astrology was increasingly thought of as an occult science or superstition by the intellectual elite. Because of their lengthy shared history, it sometimes happens that the two are confused with one another even today. Many contemporary astrologers, however, do not claim that astrology is a science, but think of it as a form of divination like the I-Ching, an art, or a part of a spiritual belief structure (influenced by trends such as Neoplatonism, Neopaganism, Theosophy, and Hinduism).

Astrology and astronomy

2008-02-02T22:15:00.000-08:00

Astrology and astronomy are historically one and the same discipline (Latin: astrologia), and were only gradually recognized as separate in western 17th century philosophy (the "Age of Reason").

Since the 18th century they have come to be regarded as completely separate disciplines. Astronomy, the study of objects and phenomena beyond the Earth's atmosphere, is accepted as a science [1][2][3] and is a widely studied academic discipline. Astrology, which uses the apparent positions of celestial objects as the basis for psychology, prediction of future events, and other esoteric knowledge, is not widely regarded as science and is typically defined as a form of divination[4][5][6][7][8][9][10].

Other areas of inquiry Cosmology

2007-12-03T21:47:00.000-08:00

Cosmologists also study:

* whether primordial black holes were formed in our universe, and what happened to them.
* the GZK cutoff for high-energy cosmic rays, and whether it signals a failure of special relativity at high energies
* the equivalence principle, and whether Einstein's general theory of relativity is the correct theory of gravitation, and if the fundamental laws of physics are the same everywhere in the universe

Dark energy

2007-12-03T21:46:00.001-08:00

If the universe is to be flat, there must be an additional component making up 71% (in addition to the 25% dark matter and 4% baryons) of the density of the universe. This is called dark energy. In order not to interfere with big bang nucleosynthesis and the cosmic microwave background, it must not cluster in haloes like baryons and dark matter. There is strong observational evidence for dark energy, as the total mass of the universe is known, since it is measured to be flat, but the amount of clustering matter is tightly measured, and is much less than this. The case for dark energy was strengthened in 1999, when measurements demonstrated that the expansion of the universe has begun to gradually accelerate.

However, apart from its density and its clustering properties, nothing is known about dark energy. Quantum field theory predicts a cosmological constant much like dark energy, but 120 orders of magnitude too large. Steven Weinberg and a number of string theorists (see string landscape) have used this as evidence for the anthropic principle, which suggests that the cosmological constant is so small because life (and thus physicists, to make observations) cannot exist in a universe with a large cosmological constant, but many people find this an unsatisfying explanation. Other possible explanations for dark energy include quintessence or a modification of gravity on the largest scales. The effect on cosmology of the dark energy that these models describe is given by the dark energy's equation of state, which varies depending upon the theory. The nature of dark energy is one of the most challenging problems in cosmology.

A better understanding of dark energy is likely to solve the problem of the ultimate fate of the universe. In the current cosmological epoch, the accelerated expansion due to dark energy is preventing structures larger than superclusters from forming. It is not known whether the acceleration will continue indefinitely, perhaps even increasing until a big rip, or whether it will eventually reverse.

Dark matter

2007-12-03T21:46:00.000-08:00

Evidence from big bang nucleosynthesis, the cosmic microwave background and structure formation suggests that about 25% of the mass of the universe consists of non-baryonic dark matter, whereas only 4% consists of visible, baryonic matter. The gravitational effects of dark matter are well understood, as it behaves like cold, non-radiative dust which forms around haloes around galaxies. Dark matter has never been detected in the laboratory: the particle physics nature of dark matter is completely unknown. However, there are a number of candidates, such as a stable supersymmetric particle, a weakly interacting massive particle, an axion, and a massive compact halo object. Alternatives to the dark matter hypothesis include a modification of gravity at small accelerations (MOND) or an effect from brane cosmology.

The physics at the center of galaxies (see active galactic nuclei, supermassive black hole) may give some clues about the nature of dark matter.

Formation and evolution of large-scale structure

2007-12-03T21:40:00.000-08:00

Understanding the formation and evolution of the largest and earliest structures (ie, quasars, galaxies, clusters and superclusters) is one of the largest efforts in cosmology. Cosmologists study a model of hierarchical structure formation in which structures form from the bottom up, with smaller objects forming first, while the largest objects, such as superclusters, are still assembling. The most straightforward way to study structure in the universe is to survey the visible galaxies, in order to construct a three-dimensional picture of the galaxies in the universe and measure the matter power spectrum. This is the approach of the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey.

An important tool for understanding structure formation is simulations, which cosmologists use to study the gravitational aggregation of matter in the universe, as it clusters into filaments, superclusters and voids. Most simulations contain only non-baryonic cold dark matter, which should suffice to understand the universe on the largest scales, as there is much more dark matter in the universe than visible, baryonic matter. More advanced simulations are starting to include baryons and study the formation of individual galaxies. Cosmologists study these simulations to see if they agree with the galaxy surveys, and to understand any discrepancy.

Other, complementary techniques will allow cosmologists to measure the distribution of matter in the distant universe and to probe reionization. These include:

* The Lyman alpha forest, which allows cosmologists to measure the distribution of neutral atomic hydrogen gas in the early universe, by measuring the absorption of light from distant quasars by the gas.
* The 21 centimeter absorption line of neutral atomic hydrogen also provides a sensitive test of cosmology
* Weak lensing, the distortion of a distant image by gravitational lensing due to dark matter.

These will help cosmologists settle the question of when the first quasars formed

Big Bang Nucleosynthesis

2007-12-03T21:38:00.001-08:00

Big Bang Nucleosynthesis is the theory of the formation of the elements in the early universe. It finished when the universe was about three minutes old and its temperature fell enough that nuclear fusion ceased. Because the time in which big bang nucleosynthesis occurred was so short, only the very lightest elements were produced, unlike in stellar nucleosynthesis. Starting from hydrogen ions (protons), it principally produced deuterium, helium-4 and lithium. Other elements were produced in only trace abundances. While the basic theory of nucleosynthesis has been understood for decades (it was developed in 1948 by George Gamow, Ralph Asher Alpher and Robert Herman) it is an extremely sensitive probe of physics at the time of the big bang, as the theory of big bang nucleosynthesis connects the abundances of primordial light elements with the features of the early universe. Specifically, it can be used to test the equivalence principle, to probe dark matter and test neutrino physics. Some cosmologists have proposed that big bang nucleosynthesis suggests there is a fourth "sterile" species of neutrino.

Big Bang Nucleosynthesis

2007-12-03T21:38:00.000-08:00

The very early universe (Areas of Study Physical Cosmology)

2007-12-03T21:37:00.001-08:00

While the early, hot universe appears to be well explained by the big bang from roughly 10-33 seconds onwards, there are several problems. One is that there is no compelling reason, using current particle physics, to expect the universe to be flat, homogeneous and isotropic (see the cosmological principle). Moreover, grand unified theories of particle physics suggest that there should be magnetic monopoles in the universe, which have not been found. These problems are resolved by a brief period of cosmic inflation, which drives the universe to flatness; smooths out anisotropies and inhomogeneities to the observed level; and exponentially dilutes the monopoles. The physical model behind cosmic inflation is extremely simple, however it has not yet been confirmed by particle physics, and there are difficult problems reconciling inflation and quantum field theory. Some cosmologists think that string theory and brane cosmology will provide an alternative to inflation.

Another major problem in cosmology is what has caused the universe to contain more particles than antiparticles. Cosmologists can use X-ray observations to deduce that the universe is not split into regions of matter and antimatter, but rather is predominantly made of matter. This problem is called the baryon asymmetry, and the theory to describe the resolution is called baryogenesis. The theory of baryogenesis was worked out by Andrei Sakharov in 1967, and requires a violation of the particle physics symmetry, called CP-symmetry, between matter and antimatter. Particle accelerators, however, measure too small a violation of CP-symmetry to account for the baryon asymmetry. Cosmologists and particle physicists are trying to find additional violations of the CP-symmetry in the early universe that might account for the baryon asymmetry.

Both the problems of baryogenesis and cosmic inflation of these problems are very closely related to particle physics, and their resolution might come from high energy theory and experiment, rather than through observations of the universe.

Timeline of the Big Bang

2007-12-03T21:35:00.000-08:00

Observations suggest that the universe as we know it began around 13.7 billion years ago. Since then, the evolution of the universe has passed through three phases. The very early universe, which is still poorly understood, was the split second in which the universe was so hot that particles had energies higher than those currently accessible in particle accelerators on Earth. Therefore, while the basic features of this epoch have been worked out in the big bang theory, the details are largely based on educated guesses. Following this, in the early universe, the evolution of the universe proceeded according to known high energy physics. This is when the first protons, electrons and neutrons formed, then nuclei and finally atoms. With the formation of neutral hydrogen, the cosmic microwave background was emitted. Finally, the epoch of structure formation began, when matter first started to aggregate into the first stars and quasars, and ultimately galaxies, clusters of galaxies and superclusters formed. The future of the universe is not yet firmly known, but according to the ?CDM model it will continue expanding forever.

Particle physics in cosmology

2007-12-03T21:34:00.001-08:00

Particle physics, which deals with high energies, is extremely important in the behavior of the early universe, since it was so hot that the average energy density was very high. Because of this, scattering processes and decay of unstable particles are important in cosmology.

As a thumb rule, a scattering or a decay process is cosmologically important in a certain cosmological epoch if its relevant time scale is smaller or comparable to the time scale of the universe expansion, which is 1 / H with H being the Hubble constant at that time. This is roughly equal to the age of the universe at that time.

Equations of motion

2007-12-03T21:34:00.000-08:00

The equations of motion governing the universe as a whole are derived from general relativity with a small, positive cosmological constant. The solution is an expanding universe; due to this expansion the radiation and matter in the universe are cooled down and become diluted. At first the expansion is slowed down by gravitation due to the radiation and matter content of the universe. However, as these become diluted, the cosmological constant becomes more dominant and the expansion of the universe starts to accelerate rather than decelerate. In our universe this has already happened, billions of years ago.

History of physical cosmology

2007-12-03T21:31:00.001-08:00

Modern cosmology developed along tandem observational and theoretical tracks. In 1915, Albert Einstein developed his theory of general relativity. At the time, physicists were prejudiced to believe in a perfectly static universe without beginning or end. Einstein added a cosmological constant to his theory to try to force it to allow for a static universe with matter in it. The so-called Einstein universe is, however, unstable. It is bound to eventually start expanding or contracting. The cosmological solutions of general relativity were found by Alexander Friedmann, whose equations describe the Friedmann-Lemaître-Robertson-Walker universe, which may expand or contract.

In the 1910s, Vesto Slipher and later Carl Wilhelm Wirtz interpreted the red shift of spiral nebulae as a Doppler shift that indicated they were receding from Earth. However, it is notoriously difficult to determine the distance to astronomical objects: even if it is possible to measure their angular size it is usually impossible to know their actual size or luminosity. They did not realize that the nebulae were actually galaxies outside our own Milky Way, nor did they speculate about the cosmological implications. In 1927, the Belgian Roman Catholic priest Georges Lemaître independently derived the Friedmann-Lemaître-Robertson-Walker equations and proposed, on the basis of the recession of spiral nebulae, that the universe began with the "explosion" of a "primeval atom"—what was later called the big bang. In 1929, Edwin Hubble provided an observational basis for Lemaître's theory. Hubble proved that the spiral nebulae were galaxies and measured their distances by observing Cepheid variable stars. He discovered a relationship between the redshift of a galaxy and its luminosity. He interpreted this as evidence that the galaxies are receding in every direction at speeds (relative to the Earth) directly proportional to their distance. This fact is known as Hubble's law. The relationship between distance and speed, however, was accurately ascertained only relatively recently: Hubble was off by a factor of ten.

Given the cosmological principle, Hubble's law suggested that the universe was expanding. This idea allowed for two opposing possibilities. One was Lemaître's Big Bang theory, advocated and developed by George Gamow. The other possibility was Fred Hoyle's steady state model in which new matter would be created as the galaxies moved away from each other. In this model, the universe is roughly the same at any point in time.

For a number of years the support for these theories was evenly divided. However, the observational evidence began to support the idea that the universe evolved from a hot dense state. Since the discovery of the cosmic microwave background in 1965 it has been regarded as the best theory of the origin and evolution of the cosmos. Before the late 1960s, many cosmologists thought the infinitely dense singularity at the starting time of Friedmann's cosmological model was a mathematical over-idealization, and that the universe was contracting before entering the hot dense state and starting to expand again. This is Richard Tolman's oscillatory universe. In the sixties, Stephen Hawking and Roger Penrose demonstrated that this idea was unworkable, and the singularity is an essential feature of Einstein's gravity. This led the majority of cosmologists to accept the Big Bang, in which the universe we observe began a finite time ago.

Energy of the cosmos

2007-12-03T21:31:00.000-08:00

Light elements, primarily hydrogen and helium, were created in the Big Bang. These light elements were spread too fast and too thinly in the Big Bang process (see nucleosynthesis) to form the most stable medium-sized atomic nuclei, like iron and nickel. This fact allows for later energy release, as such intermediate-sized elements are formed in our era. The formation of such atoms powers the steady energy-releasing reactions in stars, and also contributes to sudden energy releases, such as in novae. Gravitational collapse of matter into black holes is also thought to power the most energetic processes, generally seen at the centers of galaxies (see quasars and in general active galaxies).

Cosmologists are still unable to explain all cosmological phenomena purely on the basis of known conventional forms of energy, for example those related to the accelerating expansion of the universe, and therefore invoke a yet unexplored form of energy called dark energy[1] to account for certain cosmological observations. One hypothesis is that dark energy is the energy of virtual particles (which mathematically must exist in vacuum due to the uncertainty principle).

There is no unambiguous way to define the total energy of the universe in the current best theory of gravity, general relativity. As a result it remains controversial whether one can meaningfully say that total energy is conserved in an expanding universe. For instance, each photon that travels through intergalactic space loses energy due to the redshift effect. This energy is not obviously transferred to any other system, so seems to be permanently lost. Nevertheless some cosmologists insist that energy is conserved in some sense.[2]

Thermodynamics of the universe is a field of study to explore which form of energy dominates the cosmos - relativistic particles which are referred to as radiation, or non-relativistic particles which are referred to as matter. The former are particles whose rest mass is zero or negligible compared to their energy, and therefore move at the speed of light or very close to it; the latter are particles whose kinetic energy is much lower than their rest mass and therefore move much slower than the speed of light.

As the universe expands, both matter and radiation in it become diluted. However, the universe also cools down, meaning that the average energy per particle is getting smaller with time. Therefore the radiation becomes weaker, and dilutes faster than matter. Thus with the expansion of the universe radiation becomes less dominant than matter. In the very early universe radiation dictates the rate of deceleration of the universe's expansion, and the universe is said to be radiation dominated. At later times, when the average energy per photon is roughly 10 eV and lower, matter dictates the rate of deceleration and the universe is said to be matter dominated. The intermediate case is not treated well analytically. As the expansion of the universe continues, matter dilutes even further and the cosmological constant becomes dominant, leading to an acceleration in the universe's expansion.

Physical cosmology

2007-12-03T21:30:00.001-08:00

Physical cosmology, as a branch of astronomy, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. Cosmology involves itself with studying the motions of the celestial bodies and the first cause. For most of human history, it has been a branch of metaphysics. Cosmology as a science originates with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on earth, and Newtonian mechanics, which first allowed us to understand those motions. This is now called celestial mechanics. Physical cosmology, as it is now understood, began with the twentieth century development of Albert Einstein's theory of general relativity and better astronomical observations of extremely distant objects.

The twentieth century advances made it possible to speculate about the origins of the universe and allowed scientists to establish the Big Bang as the leading cosmological theory, which most cosmologists now accept as the basis for their theory and observations. Vanishingly few researchers still advocate any of a handful of alternative cosmologies, but professional cosmologists generally agree that the big bang best explains observations. Physical cosmology, roughly speaking, deals with the very largest objects in the universe (galaxies, clusters and superclusters), the very earliest distinct objects to form (quasars) and the very early universe, when it was nearly homogeneous (hot big bang, cosmic inflation and the cosmic microwave background radiation).

Cosmology is unusual in physics for drawing heavily on the work of particle physicists' experiments, and research into phenomenology and even string theory; from astrophysicists; from general relativity research; and from plasma physics. Thus, cosmology unites the physics of the largest structures in the universe to the physics of the smallest structures in the universe.

Criticisms

2007-12-03T21:29:00.002-08:00

Because Astrobiology relies mostly on scientific extrapolations, over solid, factual evidence, the authenticity of astrobiology as a science can be questioned. Astrobiology is more theoretical than scientific. While other branches of science remain heavily theoretical, there is a greater degree of mathematical, pragmatic and/or observational evidence supporting the theories. For example, while science cannot prove string theory, there is a great deal of mathematical computation which implies the existence of strings of energy. Such evidence does not exist with Astrobiology, save for an asteroid segment which is believed to have fossilized Martian microbes. [55] the University of Glamorgan, UK, started just such a degree in 2006.[56]

Characterization of non-Earth life is extraordinarily unsettled; hypotheses and predictions as to its existence and origin vary wildly; true astrobiological experiments (with modest exceptions such as the study of the ALH84001 meteorite and searches for indications of life in Earthshine) simply cannot occur at present. Finally, astrobiology has been criticized for being unimaginative in the tacit assumption that Earth-like life presents the most likely template for life elsewhere. For example, Michael Crow, the president of Arizona State University, said the following:[57]

For the last 3,000 years of our science, we really haven't gotten around to the notion that there might be something going on somewhere other than in this small, rural village [called Earth], in this isolated corner of our own galaxy or the Universe itself.

Biologist Jack Cohen and mathematician Ian Stewart, amongst others, consider xenobiology separate from astrobiology for this reason. Cohen and Stewart stipulate that astrobiology is the search for earth-like life outside of our solar system and say that xenobiologists are concerned with the possibilities open to us once we consider that life need not be carbon-based or oxygen-breathing, so long as it has the defining characteristics of life. See carbon chauvinism.

As with all space exploration, there is the classic argument that there is still a lot more scientists have to learn about Earth. Critics of astrobiology may prefer that federal funding remain dedicated towards searching for unknown species in our own terrestrial biosphere. They feel that earth is the most plausible and practical region to search for and study life.

Political Support

2007-12-03T21:29:00.001-08:00

In the United States, President George W. Bush's Fiscal Year 2007 NASA Budget cut funding for astrobiological research by 50 percent.[53] In the 2007 plan, $89 million will be cut from astrobiological research, partly because of a $2.3 billion error in the Space Shuttle Budget.[54] In a letter to the astrobiological community in the United States, SETI chief executive Thomas Pierson and former NAI director Baruch Blumberg said the following: "Action is needed immediately to prevent the slowing down, or even cessation, of astrobiological research".[54] Hiroshi Ohmoto, the director of the Astrobiology Research Center in Penn State, said the following in response to the budget cuts to astrobiology:[54]

Astrobiology is the reason we go into space, to answer fundamental questions about the origins of life and how it evolved, and whether there are other places where organisms are living. It is the whole justification for future space missions.

Life in the Solar System

2007-12-03T21:28:00.002-08:00

The three most likely candidates for life in the solar system (besides Earth) are the planet Mars, the Jovian moon Europa, and Saturn's moon, Titan.[38][39][40][41][42] This speculation is primarily based on the fact that (in the case of Mars and Europa) the planetary bodies may have liquid water, a molecule essential for life as we know it for its use as a solvent in cells.[43] Water on Mars is found in its polar ice caps, and newly-carved gullies recently observed on Mars suggest that liquid water may exist, at least transiently, on the planet's surface,[44] [45] and possibly in subsurface environments such as hydrothermal springs as well. At the Martian temperatures and pressures, such liquid water is likely to be highly saline.[46] As for Europa, liquid water likely exists beneath the moon's icy outer crust.[47] This water may be warmed to a liquid state by volcanic vents on the ocean floor (an especially intriguing theory considering the various types of extremophiles that live near Earth's volcanic vents), but the primary source of heat is probably tidal heating.[48][49]

Another planetary body that could potentially sustain extraterrestrial life is Saturn's largest moon, Titan.[42] Titan has been described as having conditions similar to those of early Earth; according to bbc.co.uk, "The atmosphere on Titan could be identical to that of the early Earth when life began".[50] On Titan, scientists have discovered the first liquid lakes outside of Earth, but they are made of ethane and methane, not water.[51] Additionally, Saturn's moon Enceladus may have an ocean below its icy surface.[52]

Geology (Methodology > Division Astrobiology)

2007-12-03T21:28:00.001-08:00

The fossil record provides the oldest known evidence for life on Earth.[37] By examining this evidence, geologists are able to better understand the types of organisms that arose on the early Earth. Some regions on Earth, such as the Pilbara in Western Australia are also considered to be geological analogs to regions of Mars and as such might be able to provide clues to possible Martian life.

Biology (Methodology > Division Astrobiology)

2007-12-03T21:26:00.000-08:00

Extremophiles (organisms able to survive in extreme environments) are a core research element for astrobiologists. Such organisms include biota able to survive kilometers below the ocean's surface near hydrothermal vents and microbes that thrive in highly acidic environments.[33] Characterization of these organisms—their environments and their evolutionary pathways—is considered a crucial component to understanding how life might evolve elsewhere in the universe. Recently, a number of astrobiologists have teamed up with marine biologists and geologists to search for extremophiles and other organisms living around hydrothermal vents on the floors of our own oceans. Scientists hope to use their findings to help them create hypotheses on whether life could potentially exist on certain moons in our own solar system, such as Europa.[34][35][36]

The origin of life, as distinct from the evolution of life, is another ongoing field of research. Oparin and Haldane postulated that the conditions on the early Earth were conducive to the formation of organic compounds from inorganic precursors and thus to the formation of many of the chemicals common to all forms of life we see today. The study of this process, known as prebiotic chemistry, has made some progress but it is still unclear whether or not life could have formed in such a manner on Earth. The alternative theory of panspermia is that the first elements of life may have formed on another planet with even more favourable conditions (or even in interstellar space, asteroids, etc.), and then have been carried over to Earth by a variety of means.

Astronomy (Methodology > Division Astrobiology)

2007-12-03T21:25:00.002-08:00

Most astronomy-related astrobiological research falls into the category of extrasolar planet (exoplanet) detection, the hypothesis being that if life arose on Earth then it could also arise on other planets with similar characteristics. To that end, a number of instruments designed to detect 'Earth-like' exoplanets are under development, most notably NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin programs.[27] Additionally, NASA plans to launch the Kepler mission in 2008, and the French Space Agency has already launched the COROT space mission.[28][29] There have also been several less ambitious ground-based efforts are also underway (see exoplanet).

The goal of these missions is not only to detect Earth-sized planets but also to directly detect light from the planet so that it may be studied spectroscopically. By examining planetary spectra it will be possible to determine the basic composition of an extrasolar planet's atmosphere and/or surface; given this knowledge, it may be possible to assess the likelihood of life being found on that planet. A NASA research group, the Virtual Planet Laboratory[1] (VPL), is using computer modelling to generate a wide variety of 'virtual' planets to see what they would look like if viewed by TPF or Darwin. It is hoped that once these missions come online, their spectra can be cross-checked with these 'virtual' planetary spectra for features that might indicate the presence of life. The photometry (astronomy) temporal variability of extrasolar planets may also provide clues to their surface and atmospheric properties. One mission was planned to the Jupiter moon, Europa, before recent cuts by NASA. This mission would have searched for life in the ocean of this moon.

An estimate for the number of planets with (intelligent) extraterrestrial life can be gleaned from the Drake equation, essentially an equation expressing the probability of intelligent life as the product of factors such as the fraction of planets that might be habitable and the fraction of planets on which life might arise:[30]

N = R^{*} ~ \times ~ f_{p} ~ \times ~ n_{e} ~ \times ~ f_{l} ~ \times ~ f_{i} ~ \times ~ f_{c} ~ \times ~ L

However, whilst the rationale behind the equation is sound, it is unlikely that the equation will be constrained to reasonable error limits any time soon. The first term, Number of Stars, is generally constrained within a few orders of magnitude. The second and third terms, Stars with Planets and Planets with Habitable Conditions, are being evaluated for the Sun's neighbourhood. Another associated topic is the Fermi paradox, which suggests that if intelligent life is common in the universe then there should be obvious signs of it. This is the purpose of projects like SETI, which tries to detect signs of radio transmissions from intelligent extraterrestrial civilizations.

Another active research area in astrobiology is solar system formation. It has been suggested that the peculiarities of our solar system (for example, the presence of Jupiter as a protective 'shield' or the planetary collision which created the Moon) may have greatly increased the probability of intelligent life arising on our planet.[31][32] No firm conclusions have been reached so far.

Narrowing the task (methodology Astrobiology)

2007-12-03T21:25:00.001-08:00

When looking for life on other planets, some simplifying assumptions are useful to reduce the size of the task of astrobiologists. One is to assume that the vast majority of life-forms in our galaxy are based on carbon chemistries, as are all life-forms on Earth.[22] While it is possible that non carbon-based life exists, carbon is well known for the unusually wide variety of molecules that can be formed around it. However, it should be noted that astrobiology concerns itself with an interpretation of existing scientific data; that is, given more detailed and reliable data from other parts of the universe (perhaps obtainable only by physical space exploration) the roots of astrobiology itself--biology, physics, chemistry--may have their theoretical bases challenged. Much speculation is entertained in the field to give context, but astrobiology concerns itself primarily with hypotheses that fit firmly into existing theories.

The presence of liquid water is also a useful assumption, as it is a common molecule and provides an excellent environment for the formation of complicated carbon-based molecules that could eventually lead to the emergence of life.[23] Some researchers posit environments of ammonia, or more likely water-ammonia mixtures.[24] These environments are considered suitable for carbon or noncarbon life, while opening more temperature ranges (and thus worlds) for life.

A third assumption is to focus on Sun-like stars. This comes from the idea of planetary habitability.[25] Very big stars have relatively short lifetimes, meaning that life would not likely have time to evolve on planets orbiting them. Very small stars provide so little heat and warmth that only planets in very close orbits around them would not be frozen solid, and in such close orbits these planets would be tidally "locked" to the star.[26] Without a thick atmosphere, one side of the planet would be perpetually baked and the other perpetually frozen. In 2005, the question was brought back to the attention of the scientific community, as the long lifetimes of red dwarfs could allow some biology on planets with thick atmospheres. This is significant, as red dwarfs are extremely common.

About 10% of the stars in our galaxy are Sun-like, and there are about a thousand such stars within 100 light-years of our Sun. These stars would be useful primary targets for interstellar listening. Since Earth is the only planet known to contain life, there is no way to know if any of the simplifying assumptions are correct.

Rare Earth hypothesis

2007-12-03T21:24:00.002-08:00

In the book Rare Earth: Why Complex Life is Uncommon in the Universe, Peter Ward, a geologist and paleontologist, and Donald Brownlee, an astronomer and astrobiologist, propose that life as we know it is rare in the universe.[19][20] They suggest that microbial life, however, is probably common in the universe, because of recently discovered extremophiles.[21] The book argues that the chances of all the conditions that occurred to create the Earth occurring again would be rare; thus intelligent life would be rare. One important factor focused on in the book is planetary habitability (see section below).

Peter Ward, one of the authors, said the following:[1]

How do we define life as we do know it? Life on Earth has DNA, a specific genetic code. It also uses only 20, and the same 20, amino acids. Life is always cellular according to some people, but I think not. I personally define a virus as alive. As for other life, what could it be? Could there be non-DNA life? If such life does exist, what does chemistry permit? Certainly chemistry permits certain types of life on our planet and others not. But once we move out in the solar system, especially in the vast realm of cold, chemistry changes. There could be different information systems, different solvents, different membranes. And as we go from hotter to colder, when we go to Venus, out to Mars, to Europa, and to Titan, we really should expect radically different chemistries.

Rare Earth hypothesis

2007-12-03T21:24:00.001-08:00

Elliptical galaxies

2007-12-03T21:23:00.000-08:00

Giant elliptical galaxies are probably formed by mergers on a grander scale. In the Local Group, the Milky Way and M31 (the Andromeda Galaxy) are gravitationally bound, and currently approaching each other at high speed. Since we cannot determine the speed of M31 perpendicular to the line from us to it, we do not know if it will collide with the Milky Way. If the two galaxies do meet they will pass through each other, with gravity distorting both galaxies severely and ejecting some gas, dust and stars into intergalactic space. They will travel apart, slow down, and then again be drawn towards each other, and again collide. Eventually both galaxies will have merged completely, streams of gas and dust will be flying through the space near the newly formed giant elliptical galaxy. Out of the gas ejected from the merger, new globular clusters and maybe even new dwarf galaxies may form and become the halo of the elliptical. The globulars from both M31 and the Milky Way will also form part of the halo; globulars are so tightly held together that they are largely immune to large scale galactic interactions. On the stellar scale, little will happen. If anybody is around to watch the merger, it will be a slow, but magnificent event, with the sight of a distorted M31 spectacularly spanning the entire sky. M31 is actually already distorted: the edges are warped. This is probably because of interactions with its own galactic companions, as well as possible mergers with dwarf spheroidal galaxies in the recent past - the remnants of which are still visible in the disk populations.

In our epoch, large concentrations of galaxies (clusters and superclusters) are still assembling. This "bottom-up" picture is referred to as hierarchical structure formation (similar to the SZ picture of galaxy formation, on a larger scale).

While we have learned a great deal about ours and other galaxies, the most fundamental questions about formation and evolution remain only tentatively answered.

Spiral galaxies

2007-12-03T21:22:00.000-08:00

The earliest modern theory of the formation of our galaxy (known by astronomers as ELS, after the initials of the authors of that paper, Olin Eggen, Donald Lynden-Bell, and Allan Sandage[3]) describes a single (relatively) rapid monolithic collapse, with the halo forming first, followed by the disk. Another view published in 1978 (known as SZ for its authors, Leonard Searle and Robert Zinn[4]) describes a more gradual process, with smaller units collapsing first, then later merging to form the larger components. An even more recent idea is that significant portions of the stellar halo could be stellar debris from destroyed dwarf galaxies and globular clusters that once orbited the Milky Way. The halo would then be a "newer" component made of "recycled" old parts.

In recent years, a great deal of focus has been put on understanding merger events in the evolution of galaxies. Rapid technological progress in computers have allowed much better simulations of galaxies, and improved observational technologies have provided much more data about distant galaxies undergoing merger events. After the discovery in 1994 that our own Milky Way has a satellite galaxy (the Sagittarius Dwarf Elliptical Galaxy, or SagDEG) which is currently gradually being ripped up and "eaten" by the Milky Way, it is thought these kinds of events may be quite common in the evolution of large galaxies. The Magellanic Clouds are satellite galaxies of the Milky Way that will almost certainly share the same fate as the SagDEG. A merger with a fairly large satellite galaxy could explain why M31 (the Andromeda Galaxy) appears to have a double core.

The SagDEG is orbiting our galaxy at almost a right angle to the disk. It is currently passing through the disk; stars are being stripped off of it with each pass and joining the halo of our galaxy. Eventually, only the core of SagDEG will exist. Although it will have the same mass as a large globular cluster like Omega Centauri and G1, it will appear rather different, as it has far lower surface density due to the presence of substantial amounts of dark matter, while globular clusters appear, mysteriously, to contain very little dark matter.

Further examples of satellite dwarf galaxies that are in the process of merging with the Milky Way are the Canis Major Dwarf Galaxy, discovered in 2003 and thought to be responsible for the Monoceros Ring, and the Virgo Stellar Stream, discovered in 2005.

Fundamental questions in astrophysisc

2007-12-03T21:21:00.000-08:00

In astrophysics, the questions of galaxy formation and evolution are:

* How, from a homogeneous universe, did we obtain the very heterogeneous one we live in?
* How did galaxies form?
* How do galaxies change over time?

After the Big Bang, the universe had a period when it was remarkably homogeneous, as can be observed in the Cosmic Microwave Background, the fluctuations of which are less than one part in one hundred thousand.

The most accepted view today is that all the structure we observe today was formed as a consequence of the growth of primordial fluctuations. The primordial fluctuations caused gas to be attracted to areas of denser material, hierarchically forming superclusters, clusters, galaxies, star clusters and stars. One consequence of this model is that the location of galaxies indicates areas of higher density of the early universe. Hence the distribution of galaxies is closely related to the physics of the early universe.

The observed components of galaxies (including our own Milky Way) that must be explained in, or at least not be at odds with, a theory of galactic evolution, include:

* the stellar disk is quite thin, dense, and rotates
* the stellar halo is very large, sparse, and does not rotate (or has perhaps even a slight retrograde rotation), with no apparent substructure
* halo stars are typically much older and have much lower metallicities than disk stars (there is a correlation, but there is no absolute connection between these data)
* some astronomers have identified an intermediate population of stars, variously called the "metal weak thick disk", the "intermediate population II", et al. If these are indeed a distinct population, they would be described as metal-poor (but not as poor as the halo stars), old (but not as old as the halo stars), and orbiting very near the disk, in a sort of "puffed-up", thicker disk shape.
* globular clusters are typically old and metal-poor as well, but there are a few which are not nearly as metal-poor as most, and/or have some younger stars. Some stars in globular clusters appear to be as old as the universe itself (by entirely different measurement and analysis methods)!
* in each globular cluster, all the stars were born at virtually the same time (except for a few globulars that show multiple epochs of star formation)
* globular clusters with smaller orbits (closer to the galactic center) have orbits which are somewhat flatter (less inclined to the disk), and less eccentric (more circular), while those further out have orbits in all inclinations, and tend to be more eccentric.
* High Velocity Clouds, clouds of neutral hydrogen are "raining" down on the galaxy, and presumably have been from the beginning (these would be the necessary source of a gas disk from which the disk stars formed).

On the 11th July 2007, using the 10 metre Keck II telescope on Mauna Kea, Richard Ellis of the California Institute of Technology at Pasedena and his team found six star forming galaxies about 13.2 billion light years away and therefore created when the universe was only 500 million years old [1].

Recent research as a part of the Galactic Zoo project suggests that there is an unexplained parity violation, with a greater proportion of the galaxies rotating in an anticlockwise direction when seen from the Earth[2].

Galaxy formation and evolution

2007-12-03T21:20:00.003-08:00

The formation of galaxies is still one of the most active research areas in astrophysics; and, to some extent, this is also true for galaxy evolution. Some ideas, however, have gained wide acceptance.

Galaxy formation is presently believed to proceed directly from structure formation theories, formed as a result of tiny quantum fluctuations in the wake of the Big Bang. N-body simulations have also been able to predict the types of structures, morphologies, and distribution of galaxies which we observe today both in our present universe, and - by examining distant galaxies - in the early universe.

Subcategories of Galactic Astronomy

2007-12-03T21:20:00.002-08:00

A standard set of subcategories is used by astronomical journals to split up the subject of Galactic Astronomy:
1. abundances - the study of the location of elements heavier than helium
2. bulge - the study of the bulge around the center of the Milky Way
3. center - the study of the central region of the Milky Way
4. disk - the study of the Milky Way disk (the plane upon which most galactic objects are aligned)
5. evolution - the evolution of the Milky Way
6. formation - the formation of the Milky Way
7. fundamental parameters - the fundamental parameters of the Milky Way (mass, size etc)
8. globular clusters - globular clusters within the Milky Way
9. halo - the large halo around the Milky Way
10. kinematics and dynamics - the motions of stars and clusters
11. nucleus - the region around the black hole at the center of the Milky Way (Sagittarius A*)
12. open clusters and associations - open clusters and associations of stars
13. solar neighbourhood - nearby stars
14. stellar content - numbers and types of stars in the Milky Way
15. structure - the structure (spiral arms etc)

Galactic astronomy

2007-12-03T21:20:00.001-08:00

Galactic astronomy is the study of our own Milky Way galaxy and all its contents. This is in contrast to extragalactic astronomy, which is the study of everything outside our galaxy, including all other galaxies.

Galactic astronomy should not be confused with galaxy formation and evolution, which is the general study of galaxies, their formation, structure, components, dynamics, interactions, and the range of forms they take.

Our own Milky Way galaxy, where our solar system belongs, is in many ways the best studied galaxy, although important parts of it are obscured from view in visible wavelengths by regions of Cosmic dust. The development of radio astronomy, infrared astronomy and submillimeter astronomy in the 20th Century allowed the gas and dust of the Milky Way to be mapped for the first time.

Fundamental questions

2007-11-30T05:59:00.000-08:00

Research outcomes

2007-11-28T00:00:00.001-08:00

As of 2007, there is no direct evidence of extraterrestrial life.[16] Although examination of the ALH84001 meteorites, which were recovered in Antarctica and are thought to have originated from the planet Mars have provided what some scientists suggested to be microfossils of extraterrestrial life, the interpretation is disputed.[17] In 2004, the spectral signature of methane was detected in the Martian atmosphere by both Earth-based telescopes as well as by the Mars Express probe. Methane is predicted to have a relatively short half-life in the Martian atmosphere, so the gas must be actively replenished. Since one possible source, active volcanism, has thus far not been detected on Mars, this has led scientists to speculate that the source could be (microbial) life - as terrestrial methanogens are known to produce methane as a metabolic byproduct.

Missions to other planetary bodies, such as Mars Science Laboratory, ExoMars, Beagle 2: Evolution to Mars, the Cassini probe to Saturn's moon Titan), and the "Ice Clipper" mission to Jupiter's moon Europa hope to further explore the possibilities of life on other planets in our solar system.

Efforts to answer secondary questions, such as the abundance of potentially habitable planets in habitable zones and chemical precursors, have had much success. Numerous extrasolar planets have been detected using the "wobble method" and transit method, showing that planets around other stars are more diverse than previously postulated. The first Earth-like extrasolar planet to be discovered within its star's habitable zone is Gliese 581 c, which was found using radial velocity.[18]

Due to technological limitations, most of the planets so far discovered have been hot gas giants, thought to be inhospitable to any life. It is possible that some of these planets may have moons with solid surfaces or oceans that are more hospitable. It is not yet known whether our solar system, with rocky, metal-rich inner planets ideal for life, is of an aberrant composition. Improved detection methods and increased observing time will undoubtedly discover more planetary systems, and possibly some more like ours. For example, NASA's Kepler Mission seeks to discover Earth-sized planets around other stars, by measuring minute changes in the star's light curve as the planet passes between the star and the spacecraft. Research into the environmental limits of life and the workings of extreme ecosystems is also ongoing, enabling researchers to predict what planetary environments might be most likely to harbor life.

Progress in infrared astronomy and submillimeter astronomy has revealed the constituents of other star systems. Infrared searches have detected belts of dust and asteroids around distant stars, underpinning the formation of planets. Some infrared images purportedly contain direct images of planets, though this is disputed. Infrared and submillimeter spectroscopy has identified a growing number of chemicals around stars which underpin the origin or maintenance of life.

Overview Astrobiology

2007-11-28T00:00:00.000-08:00

Although astrobiology is an emerging field, and still a developing subject, the question of whether life exists elsewhere in the universe is a verifiable hypothesis and thus a valid line of scientific inquiry. Astrobiology is a multidisciplinary field utilizing physics, biology, and geology as well as philosophy to speculate about the nature of life on other worlds. One commentator on the field, planetary scientist David Grinspoon, calls astrobiology a field of natural philosophy, grounding speculation on the unknown in known scientific theory (Grinspoon 2003). Since we have only one example of a planet with life (the Earth), most of the work is speculative and based on current understanding of physics, biochemistry, and biology.[11][12]

Though once considered outside the mainstream of scientific inquiry, astrobiology has become a formalized field of study. NASA now hosts an Astrobiology Institute.[13] Additionally, a growing number of universities in the United States (e.g., University of Arizona, Penn State University, and University of Washington) Canada, Britain, and Ireland now offer graduate degree programs in astrobiology.

A particular focus of current astrobiology research is the search for life on Mars.[14] There is a growing body of evidence to suggest that Mars has previously had a considerable amount of water on its surface; water is considered to be an essential precursor to the development of life, although this has not been conclusively proven.[15] At the present, the creation of theory to inform and support the exploratory search for life may be considered astrobiology's most concrete practical application.

Missions specifically designed to search for life include the Viking program and Beagle 2 probes, both directed to Mars. The Viking results were inconclusive and Beagle 2 failed to transmit from the surface and is assumed to have crashed. A future mission with a strong astrobiology role would have been the Jupiter Icy Moons Orbiter, designed to study the frozen moons of Jupiter—some of which may have liquid water—had it not been canceled. In 2009, NASA plans to launch the Mars Science Laboratory Rover which will continue the search for past or present life on Mars using a suite of scientific instruments.

Astrobiology

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This article is about the scientific discipline. For the journal, see Astrobiology (journal).

Astrobiology (from Greek: ἀστρο, astro, "constellation"; βίος, bios, "life"; and λόγος, logos, "knowledge") is the interdisciplinary study of life in space, combining aspects of astronomy, biology and geology.[2] It is focused primarily on the study of the origin, distribution and evolution of life. It is also known as exobiology (from Greek: έξω, exo, "outside").[3][4][5] The term "Xenobiology" has been used as well, but this is technically incorrect because its terminology means "biology of the foreigners".[6]

Some major astrobiological research topics include:[2][7][8][9] What is life? How did life arise on Earth? What kind of environments can life tolerate? How can we determine if life exists on other planets? How often can we expect to find complex life? What will life consist of on other planets? Will it be DNA/Carbon based or based on something else?[1] What will it look like?

Amateur astronomy

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Collectively, amateur astronomers observe a variety of celestial objects and phenomena sometimes with equipment that they build themselves. Common targets of amateur astronomers include the Moon, planets, stars, comets, meteor showers, and a variety of deep-sky objects such as star clusters, galaxies, and nebulae. One branch of amateur astronomy, amateur astrophotography, involves the taking of photos of the night sky. Many amateurs like to specialize in the observation of particular objects, types of objects, or types of events which interest them.[44][45]

Most amateurs work at visible wavelengths, but a small minority experiment with wavelengths outside the visible spectrum. This includes the use of infrared filters on conventional telescopes, and also the use of radio telescopes. The pioneer of amateur radio astronomy was Karl Jansky who started observing the sky at radio wavelengths in the 1930s. A number of amateur astronomers use either homemade telescopes or use radio telescopes which were originally built for astronomy research but which are now available to amateurs (e.g. the One-Mile Telescope).[46][47]

Amateur astronomers continue to make scientific contributions to the field of astronomy. Indeed, it is one of the few scientific disciplines where amateurs can still make significant contributions. Amateurs can make occultation measurements that are used to refine the orbits of minor planets. They can also discover comets, and perform regular observations of variable stars. Improvements in digital technology have allowed amateurs to make impressive advances in the field of astrophotography.[48][49][50]

Major questions in astronomy

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Although the scientific discipline of astronomy has made tremendous strides in understanding the nature of the universe and its contents, there remain some important unanswered questions. Answers to these may require the construction of new ground- and space-based instruments, and possibly new developments in theoretical and experimental physics.

* What is the origin of the stellar mass spectrum? That is, why do astronomers observe the same distribution of stellar masses—the initial mass function—apparently regardless of the initial conditions?[51] A deeper understanding of the formation of stars and planets is needed.
* Is there other life in the Universe? Especially, is there other intelligent life? If so, what is the explanation for the Fermi paradox? The existence of life elsewhere has important scientific and philosophical implications.[52][53]
* What is the nature of dark matter and dark energy? These dominate the evolution and fate of the cosmos, yet we are still uncertain about their true natures.[54]
* Why did the universe come to be? Why, for example, are the physical constants so finely tuned that they permit the existence of life? Could they be the result of cosmological natural selection? What caused the cosmic inflation that produced our homogeneous universe?[55]
* What will be the ultimate fate of the universe?[56]

Interdisciplinary studies

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Astronomy and astrophysics have developed significant interdisciplinary links with other major scientific fields. These include:

* Astrobiology: the study of the advent and evolution of biological systems in the universe.
* Archaeoastronomy: the study of ancient or traditional astronomies in their cultural context, utilizing archaeological and anthropological evidence.
* Astrochemistry: the study of the chemicals found in space, usually in molecular clouds, and their formation, interaction and destruction. It represents an overlap of the disciplines of astronomy and chemistry.
* Cosmochemistry: the study of the chemicals found within the Solar System, including the origins of the elements and variations in the isotope ratios.

Cosmology

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Cosmology (from the Greek κοσμος "world, universe" and λογος "word, study") could be considered the study of the universe as a whole.

Observations of the large-scale structure of the universe, a branch known as physical cosmology, have provided a deep understanding of the formation and evolution of the cosmos. Fundamental to modern cosmology is the well-accepted theory of the big bang, wherein our universe began at a single point in time, and thereafter expanded over the course of 13.7 Gyr to its present condition. The concept of the big bang can be traced back to the discovery of the microwave background radiation in 1965.

In the course of this expansion, the universe underwent several evolutionary stages. In the very early moments, it is theorized that the universe experienced a very rapid cosmic inflation, which homogenized the starting conditions. Thereafter, nucleosynthesis produced the elemental abundance of the early universe. (See also nucleocosmochronology.)

When the first atoms formed, space became transparent to radiation, releasing the energy viewed today as the microwave background radiation. The expanding universe then underwent a Dark Age due to the lack of stellar energy sources.[41]

A hierarchical structure of matter began to form from minute variations in the mass density. Matter accumulated in the densest regions, forming clouds of gas and the earliest stars. These massive stars triggered the reionization process and are believed to have created many of the heavy elements in the early universe.

Gravitational aggregations clustered into filaments, leaving voids in the gaps. Gradually, organizations of gas and dust merged to form the first primitive galaxies. Over time, these pulled in more matter, and were often organized into groups and clusters of galaxies, then into larger-scale superclusters.[42]

Fundamental to the structure of the universe is the existence of dark matter and dark energy. These are now thought to be the dominant components, forming 96% of the density of the universe. For this reason, much effort is expended in trying to understand the physics of these components.[43]

Extragalactic astronomy

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The study of objects outside of our galaxy is a branch of astronomy concerned with the formation and evolution of Galaxies; their morphology and classification; and the examination of active galaxies, and the groups and clusters of galaxies. The latter is important for the understanding of the large-scale structure of the cosmos.

Most galaxies are organized into distinct shapes that allow for classification schemes. They are commonly divided into spiral, elliptical and Irregular galaxies.[38]

As the name suggests, an elliptical galaxy has the cross-sectional shape of an ellipse. The stars move along random orbits with no preferred direction. These galaxies contain little or no interstellar dust; few star-forming regions; and generally older stars. Elliptical galaxies are more commonly found at the core of galactic clusters, and may be formed through mergers of large galaxies.

A spiral galaxy is organized into a flat, rotating disk, usually with a prominent bulge or bar at the center, and trailing bright arms that spiral outward. The arms are dusty regions of star formation where massive young stars produce a blue tint. Spiral galaxies are typically surrounded by a halo of older stars. Both the Milky Way and the Andromeda Galaxy are spiral galaxies.

Irregular galaxies are chaotic in appearance, and are neither spiral nor elliptical. About a quarter of all galaxies are irregular, and the peculiar shapes of such galaxies may be the result of gravitational interaction.

An active galaxy is a formation that is emitting a significant amount of its energy from a source other than stars, dust and gas; and is powered by a compact region at the core, usually thought to be a super-massive black hole that is emitting radiation from in-falling material.

A radio galaxy is an active galaxy that is very luminous in the radio portion of the spectrum, and is emitting immense plumes or lobes of gas. Active galaxies that emit high-energy radiation include Seyfert galaxies, Quasars, and Blazars. Quasars are believed to be the most consistently luminous objects in the known universe.[39]

The large-scale structure of the cosmos is represented by groups and clusters of galaxies. This structure is organized in a hierarchy of groupings, with the largest being the superclusters. The collective matter is formed into filaments and walls, leaving large voids in between.[40]

Galactic astronomy

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Our solar system orbits within the Milky Way, a barred spiral galaxy that is a prominent member of the Local Group of galaxies. It is a rotating mass of gas, dust, stars and other objects, held together by mutual gravitational attraction. As the Earth is located within the dusty outer arms, there are large portions of the Milky Way that are obscured from view.

In the center of the Milky Way is the core, a bar-shaped bulge with what is believed to be a supermassive black hole at the center. This is surrounded by four primary arms that spiral from the core. This is a region of active star formation that contains many younger, population II stars. The disk is surrounded by a spheroid halo of older, population I stars, as well as relatively dense concentrations of stars known as globular clusters.^[34]^[35]

Between the stars lies the interstellar medium, a region of sparse matter. In the densest regions, molecular clouds of molecular hydrogen and other elements create star-forming regions. These begin as irregular dark nebulae, which concentrate and collapse (in volumes determined by the Jeans length) to form compact protostars.^[36]

As the more massive stars appear, they transform the cloud into an H II region of glowing gas and plasma. The stellar wind and supernova explosions from these stars eventually serve to disperse the cloud, often leaving behind one or more young open clusters of stars. These clusters gradually disperse, and the stars join the population of the Milky Way.

Kinematic studies of matter in the Milky Way and other galaxies have demonstrated that there is more mass than can be accounted for by visible matter. A dark matter halo appears to dominate the mass, although the nature of this dark matter remains undetermined.^[37]