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Dressing properly for an observing session is vital if you want to stay warm and enjoy the experience.
This article tells you how to do just that.
First Mistakes
Most people, at some time in their lives, look up at the night sky. Some are awe-struck, others mildly interested, and still others are not even aware that they have looked up in the first place, and consequently go about their lives oblivious to the 99.99% of the universe which is not Earth-based! Those who are filled with wonder usually develop their interest fully, and join an astronomical society, while those with a mild interest may venture out again, perhaps to a Star Party. What happens? They arrive in suits and dresses - the most inappropriate clothing - freeze, and then decide that astronomy is not for them. It cannot be emphasized enough that one must be adequately prepared for ob serving. Clothing is all-important, and as seen in fig. 1, incorporates several layers of loose-fitting and warm items. You may vary in the make-up of your protective clothing, but ensure that you are warm. Always wear a hat as it is estimated that up to 60% of body heat is lost through the head.
What to Take With You
It is normal to take breaks during an observing session in order to warm up and to rest the eyes. After 30 minutes or so, in -2C, a cup of hot soup, coffee or cocoa is very welcome, and only involves a few minutes of preparation before setting out. So, bring a flask. If you are going out on a general naked-eye or meteor ob serving session, bring a plastic groundsheet to lie on, or a reclining deck-chair (if you can carry it). These reduce the risk of neck strain due to cold muscles, and prolonged neck flexion if standing.
On the astronomy side, a star map is a must. This can take the form of a single sheet (such as the Philip's Chart of the Stars), or a multi-chart format, as in Norton's Star Atlas. A plan sphere can also be useful in helping the beginner to locate individual constellations and stars. This, and the star maps, may be obtained from good bookshops. Bring a red torch, such as a bicycle back light, for reading maps and charts. Red light places less strain on the eyes than white, and so causes little disruption to dark adapted eyes. A clip board with blank, white paper, and a HB pencil, should be brought for recording details of objects seen, and drawings of meteors, etc. These can be transferred into a formal observing log later on, after the watch.
What to Look For
Many of the nights spent observing will merely involve you in becoming familiar with the night sky. This must be the first step on the road towards proficiency in astronomical observing, as it is only by becoming familiar with the "unchanging sky" that one can begin to notice those objects which move. Learning constellation names and stars takes many hours of practice and observing. A series of articles on constellations has been featured in this and prior issues of Orbit and these will form a basis on which inexperienced astronomers can develop that required learning. In the meantime though, identify the most famous constellations such as the Plough (Ursa Major), Orion and Cassiopeia. As you observe, you will notice several interesting differences between particular stars: First, some are brighter than others. This relative brightness of stars (and other celestial objects) is called Magnitude, and is dependant on the luminosity of the star and its distance from Earth. It should be noted that, on the magnitude scale, the brighter the star, the lower its assigned magnitude (hence - 1 is brighter than +1).
Second, you will see some stars that appear to be made up of two components. These are double stars, and may involve a pair of stars revolving about a common centre of gravity under the influence of their mutual gravitational attraction (a Binary star), or two stars which appear close together because they lie nearly in the same direction from Earth, but are in fact many light years apart (an Optical double star). Look at the second star in the "handle" of the Plough and you will see the optical double, Mizar and Alcor.
Thirdly, you may notice that not all stars are the same color. For example, Betelgeuse, at the top left corner of Orion, appears vividly red when contrasted with Rigel, at the bottom right corner, which seems bluish white. This is due to the fact that these stars belong to different spectral types, and so possess different characteristics.
Scattered throughout the sky are closely-knit groups of stars, called star clusters. These may be wide open, as with the Hyades, or closer as with the Pleiades, both of which are in Taurus. Other groups of stars take on what appears to be a much, much tighter grouping. This may be due to the vast distance between them and us, perhaps placing them outside our own galaxy. These are themselves galaxies, and one naked-eye example is the Andromeda Galaxy, which is estimated to be some 2.2 million light years away, and appears as a faint "fuzzy star". Our own galaxy - the Milky Way - is more observable, stretching across the sky as a wide band of luminosity. Mention should also be made of nebulae. These clouds of interstellar dust, often associated with stellar development, are difficult to see with the unaided eye, though one - the Great Nebula in Orion, may be observed as a luminous patch in the centre of Orion's Sword. A useful method for observing faint objects is the Averted Vision technique. All that is involved to locate an object is to look at it and then avert your eyes slightly away from it. Often the object will be noticed "through the corner of your eye", so to speak.
All of the above objects are unchanging in the night sky. Other star like bodies will be noticed, in the sky, though, which are not on the star charts and which appear to change their positions nightly. These are the planets, and six are visible to the naked-eye - Mercury, Venus, Mars, Jupiter, Saturn and sometimes Uranus.
The planets are different to stars in several ways. A star may be defined as a luminous, gaseous body that generates energy by means of nuclear fusion reactions in its core. A planet on the other hand, is a body which orbits the Sun or another star and shines by reflected light. To the naked-eye observer, the main interest in planets lies in tracing their paths across the sky, and noting how some tend to backtrack as the months pass by.
The Moon displays little to those without optical aid, but does go through a monthly cycle of phases. An interesting exercise is to judge the positions of the Earth and Moon with respect to the Sun during each phase. Look out also for occultation - that is when the Moon passes over a star or planet. Predictions for these are listed in the Sky notes.
Very occasionally, a bright comet may grace our skies. This may appear either as a "fuzzy star" or as a classic comet, with a prominent head and streaming tail. More often though, the only sight of cometary’s matter which we can see every night, is observed to whiz across the sky in less than a second. These star like objects are, of course, meteors or shooting stars, and are usually caused when the Earth passes through dust spread out along the orbit of a comet. Rates during these meteor showers may rise to as many as 100 per hour. Full de- tails of current meteor showers are given in the Sky notes. Often, new observers mistake slow-moving objects which cross the sky in a matter of minutes, for meteors. These are in fact, manmade artificial satellites in Earth orbit. One of the most interesting of these at present is the International Space Station, which is regularly seen over
Is Light Pollution A Problem?
Frankly, yes. But this does not rule out observing in urban areas. Light pollution, while reducing the number and quality of observable objects, does not block out all stars or planets. A colleague once suggested the use of a cardboard box, placed over the head and resting on the shoulders, as a method for dealing with troublesome light. This blinkers the lateral views of the observer and I can vouch for its effectiveness. You may think that you will look ridiculous with such a contraption on your head, but let's face it, people generally consider astronomers to be weird anyway!
Conclusion
The most significant way of getting started in astronomy, whether young or old, is to join an astronomical association. There, you will find other ordinary people who have been amateur astronomers for many years, and who will be more than pleased to advise and help you on the road to becoming proficient in the science of amateur astronomy.
