1. Stepping outside
On stepping from a well lit room to your spot under the stars, you might notice that you can’t see very many at first. The stars that you do see are the brightest and so your eyes do not need to adjust very much to collect light from them. The faintest, on the other hand, stay hidden until your pupils adapt to night vision. This can be a problem especially when you want to look at a star map or a planisphere and using a dazzling torch can be more of a hindrance than a help! Your eyes react to white light more than red light, so whether you’re hunting for your ideal telescope, binoculars or are just planning on unaided observing for the time being, add a red light torch to your shopping list. You can pick them up from many astronomy instrument dealers.
To get the best views possible, you need to take care where you place your telescope. A stable surface is essential, so that rules out bumpy lawns. Concrete provides a stable surface but it also retains heat that has built up during the day and, as a result, this warmth is emitted at night – this creates air currents that can cause shimmering images through your telescope. Remember if kept indoors before use, your telescope also needs a good half an hour to cool down to the ambient temperature outdoors.
3. Look south
Pick a spot with a good southern view. The 23 degree tilt of the Earth means that more can be seen towards the south than the north from UK latitudes. Have an idea of what you want to view before you go outside – this will help direct your evening’s observing and if you have taken the time to print off sky charts or find charts in books or magazines like this one, it will speed things up.
4. Averted vision
Don’t expect too much from your first night. Forget notions of seeing things like what the Hubble Space Telescope sees through your telescope – there’s a reason why deep sky objects like galaxies and nebulae are called faint fuzzies. However, there are things you can do to make these faint objects seem more visible. A clever tactic is to use something called averted vision. In your eye, there are two different types of receptor – one type being the cone cells, which are concentrated mostly in the middle of your eye and give you colour vision, whereas the other are rod cells, which are on the periphery of your eye and are more light sensitive than cones, providing you with night vision. When looking at a faint object through the telescope eyepiece, if you just look off to one side of the object through the eyepiece while keeping the object on the periphery of your vision, it will appear brighter because the rod cells around the outside of your eye are more sensitive to the dim light of the object.
Experiment with the magnification on various eyepieces – you will find that different magnifications work better on different objects. Also try out different filters – an oxygen III filter is often called a ‘nebula filter’ as it blocks out all the light except for that wavelength of light emitted by oxygen atoms in nebulae in space. It can also double up well as a light pollution filter, blocking that annoying light blight that you might unfortunately meet during an observing session!
Tomorrow: Choosing your equipment