Observer's Year e-bog

It was on ce said that 'the night sky always looks much the same'. In fact, nothing could be further from the truth. There are 365 days in each year (366 in a Leap Year!), and from an astronomical point of view no two are alike. What I aim to do, in this book, is to go through a complete year and point out some special items of interest for each night. It may be a double star, a vari- able star or a nebula; it may be a planet, or even the Moon in some particular aspect - there is plenty of variety. (Anyone unfamiliar with astronomical terms should consult the Glossary at the end ofthis book. ) Let it be said at once that you do not need a large and expensive telescope. A surprising amount can be seen with the naked eye, and binoculars give increased range; indeed, it is probably fair to say that good binoc- ulars are ideal for the beginner, and are far better than very small telescopes. Telescopes are of two types: refractors, and reflectors. A refractor collects its light by means of a glass lens known as an object-glass (OG); the light passes down the telescope tube and is brought to focus, where an image is formed and is then magnified by a second lens, termed an eyepiece.