The French astronomer Charles Messier (1730–1817) created a list of 103 deep–sky objects (star clusters, nebulae and galaxies) that was first published in 1774. Later, other astronomers added a few more objects and today the list contains 110 objects. In the charts on the following six pages and in the star charts on pages 40–79 these objects are labeled with the number from his list with the prefix M (like M42, M78, etc).

Messier was a ‘comet hunter’, and while scanning the sky from his observatory in Paris he frequently ran into faint objects that could be mistaken for comets. He compiled the list to help him distinguish between the real comets and these permanent objects. Although most of the objects in Messier's list were later included in larger catalogs of deep-sky objects, Messier's list remains immensely popular amongst amateur observers. That is why the charts on the following eight pages focus on these objects.

All Messier objects are clearly plotted on the charts, against a background showing all stars brighter than magnitude 5.5. The meaning of the word magnitude is explained on page 31. For the abbreviations used in the column head, you may refer to page 38. The symbols used for the different types of objects are the same as used in the main star charts.