Written by Gemma Lavender
The hobby of astronomy can be bewildering for the beginner without advice to guide them. There are so many types of telescope, not to mention mounts, eyepieces, filters and other assorted accessories that it’s easy to rapidly become confused. Hopefully though, we can help you navigate your way through and make choosing the right instrument an enjoyable experience rather than a daunting one.
A lot of people think that to be an astronomer you must have a telescope. This is far from the truth! The unaided eye can show you constellations, the Moon, bright planets, even the odd galaxy or star cluster on a dark night. Binoculars are an inexpensive option to increase the range of what you can see. The most recommended are a pair of 10x50s, which, with a lens diameter of 50mm and a magnification of 10x, can show you the moons of Jupiter, the craters on the Moon, the brightest galaxies, nebulae and star clusters, even the stars of the Milky Way. The minimum size and magnification of binoculars for astronomy is 7×40, which may suit older observers – as you age the diameter of your dilated pupil shrinks, which means some observers will not get the benefit that larger diameter 10×50 binoculars offer. Of course, if you decide astronomy isn’t for you, then at least you haven’t spent hundreds of pounds on binoculars and they can still be used for terrestrial objects.
If you do go for a telescope, the most important quality to look out for is the aperture diameter, not the magnification. Beware cheap ‘toy’ telescopes that are small but claim “500x magnification!” To see faint objects your telescope needs to be able to collect as much light as possible, and so the wider the aperture (i.e. the wider the diameter of the telescope tube), the fainter the object you can see. A minimum aperture is around 100mm (four inches) for a refracting telescope and 100-150mm (four to six inches) for a reflecting telescope like a Dobsonian. Refractors use lenses to focus the light; reflectors use mirrors. You may also want to consider spending a little more on a computerised GoTo mount, which features a hand controller that can direct your telescope to any astronomical object you wish to have a gander at. A good beginners telescope should cost between £200 and £500, and they are available from reputable dealers such as those that are advertised with All About Space to manufacturers such as Celestron, Meade and Sky-Watcher.
Know your mount
The most basic type of mount allowing up and down as well as left and right motion of your telescope.
By aligning with the North Star (Polaris), the equatorial mount allows the user to track the motion of stars about the sky.
Tomorrow: Understand the celestial sphere