LITMIR.BIZ

Copyright

      Published by Collins

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      In association with

      Royal Museums Greenwich, the group name for the National Maritime Museum,

      Royal Observatory Greenwich, Queen’s House and Cutty Sark

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      © HarperCollins Publishers 2018

      Text and illustrations © Storm Dunlop and Wil Tirion

      Photographs © see acknowledgements here

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      A catalogue record for this book is available from the British Library

      eBook Edition © Sep 2018

      ISBN 9780008311643

      Version: [2018-07-14]

      Contents

       Cover

       Title Page

Copyright

Introduction

       The Constellations

The Northern Circumpolar Constellations

Comets and the Moon

Map of the Moon

       Introduction to the Month-by-Month Guide

       Month-by-Month Guide

       January

       February

       March

       April

       May

       June

       July

       August

       September

       October

       November

       December

       Glossary and Tables

       Acknowledgements

       Further Information

       About the Publisher

Introduction

      The aim of this Guide is to help people find their way around the night sky, by showing how the stars that are visible change from month to month and by including details of various events that occur throughout the year. The objects and events described may be observed with the naked eye, or nothing more complicated than a pair of binoculars.

      The conditions for observing naturally vary over the course of the year. During the summer, twilight may persist throughout the night and make it difficult to see the faintest stars. There are three recognized stages of twilight: civil twilight, when the Sun is less than 6° below the horizon; nautical twilight, when the Sun is between 6° and 12° below the horizon; and astronomical twilight, when the Sun is between 12° and 18° below the horizon. Full darkness occurs only when the Sun is more than 18° below the horizon. During nautical twilight, only the very brightest stars are visible. During astronomical twilight, the faintest stars visible to the naked eye may be seen directly overhead, but are lost at lower altitudes. As the diagram shows, during June and most of July full darkness never occurs at the latitude of London, and at Edinburgh nautical twilight persists throughout the whole night, so at that latitude only the very brightest stars are visible.

      Another factor that affects the visibility of objects is the amount of moonlight in the sky. At Full Moon, it may be very difficult to see some of the fainter stars and objects, and even when the Moon is at a smaller phase it may seriously interfere with visibility if it is near the stars or planets in which you are interested. A full lunar calendar is given for each month and may be used to see when nights are likely to be darkest and best for observation.

      The celestial sphere

      All the objects in the sky (including the Sun, Moon and stars) appear to lie at some indeterminate distance on a large sphere, centred on the Earth. This celestial sphere has various reference points and features that are related to those of the Earth. If the Earth’s rotational axis is extended, for example, it points to the North and South Celestial Poles, which

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