INTRODUCTION TO ASTRONOMY

This article featured in the November 2002 Beginners Magazine

FIRST CONTACT WITH ASTRONOMY

This is the first article introducing a series of a new features which will continue through this session until June 2003. The aim is to provide advice for complete newcomers to astronomy. It will give advice on how to get started and what is needed. Later articles will give guidance on moving up to purchase equipment, where to get it and how to use it. This first article is focused on the absolute newcomer who has no knowledge of astronomy at all.

One of the first questions asked, when thinking about taking up astronomy as a hobby is, 'what equipment do I need ?'. The simple answer is, very little to get started. A clear night and a star chart is enough. Star charts can be bought from most of the larger book shops, such as W. H. Smith.

Some charts my be a bit complicated for a first time observer or a younger person so a cheap simple one may be best. Many of the monthly astronomy magazines have a simple but very good chart showing the sky as it appears in the current month, with only the brightest stars shown. Astronomy Now is the most popular British magazine, is available from W. H. Smith and costs £2.85 every month. The advantage of buying a monthly magazine is it also gives guidance to any special events occurring that month and interesting things to look for. It also has many interesting articles on a wide range of astronomical subjects. The chart and 'what's up guide at the back of this magazine may also be used.

Having obtained a star chart the next important thing is to wait for a clear night, in Britain this may be a long time coming. When that clear night does arrive, some thought must be given to where the first observations will be made from. The position must of course be away from lights. Street lights will cause the pupils of your eyes to close much like the aperture on a camera. The darker it is the wider your eye will open to allow more light in and fainter objects to be seen. If the garden is to be used, find a position shaded from lights. If necessary erect a screen to block out the glare from the offending lights. A sheet hung over a washing line might be a useful solution.

Having found this position, shaded from irritating lights, the observers should make themselves comfortable. Warm clothes are essential even on summer nights. Sitting still for a long time in the cool night air will soon cause discomfort and ruin the enjoyment of the session. A deck chair or a lounger will provide a very comfortable reclining position to avoid neck ache through looking up into the sky for a long period of time. A sleeping bag or duvet is good on a cold winter night and a hat should be worn because about 20% of our body heat is lost through the head.

As it will be dark, a torch will be needed to see the star chart. Do not use a white light torch because it will ruin your night vision. Your eyes will take about 10 to 15 minutes to fully open but a flash of light will cause them to close up and the fainter stars will not be seen for another ten minutes. A small red light is best, perhaps a rear cycle lamp. Even a cycle lamp will be too bright so a piece of card with a small hole (10mm diameter) placed over the lamp will be about right. The card can be secured using adhesive tape or rubber bands.

The final preparation is to find a start point in the sky and here is a little problem, the stars appear to move across the sky. This means they will be in a slightly different position at different times. From hour to hour and night to night. What we must do is try to recognise a familiar position or pattern of stars.

Some of the brighter stars appear to form patters in the night sky and seem to be associated with each other, we call these groups of stars Constellations. The stars in these groups are more often than not un-associated and may be further from each other than they are from us. Some constellations like LEO (The Lion) and Orion (The Hunter) do look rather like what they a named after but still need a little imagination. Most however have no recognisable shape but still have an apparent association with the other members of the group.

Constellations are not all the same size and are defiantly not the same shape so it is difficult to know where one ends and another begins. Star charts will show where the borders are but it is not really important to the astronomer because the main pattern is only used to identify the approximate area of sky to be searched for other objects.

The method used to find interesting objects in a constellation is called 'star hopping'. Star hopping involves firstly finding the constellation in which the target is located or is near. Then by finding two or more stars within the constellation, they are used as a guideline to point towards the target object. It may be necessary to use a number of stages to route out an illusive object, by first finding the direction to a particular star then using that star and another to plot out the position of the target.

To become familiar with the constellations requires nothing more than a clear night and a simple star chart. As familiarity increases then a pair of binoculars might be useful to identify the fainter members of a constellation. We will consider observing with binoculars next month. Under the chart on What's up This Month is a guide to how to orient the chart to the sky.

As a final piece of advice, have a look around your area to see if you have a local astronomical society or club. If not ask your friends if they would like to join you in you exploration of the sky. It is much more fun to share your hobby what ever it is and by meeting people who are more experienced, you can learn from them.

Return to Introduction to Astronomy