The Messier Catalogue was compiled by French astronomer Charles Messier
in the 18th
century. The catalogue is not scientifically organised by object type or by location (as the later New General Catalogue would be). Nonetheless, it comprises examples of every known deep sky object, including galaxies, planetary nebulae, open clusters, and globular clusters. Because these objects were accessible to the relatively small aperture telescope (approximately 102 mm, or 4 inches) used by Messier to study the sky, they are among the most spectacular deep sky objects available to modern amateur astronomers using much better equipment.
All of the Messier objects are visible with binoculars or small telescopes (under favourable conditions), they are popular viewing objects for amateur astronomers. In early spring, astronomers sometimes gather for "Messier marathons", when all of the objects can be viewed over a single night.
Table of Messier objects - click to find out more about them on Wikipedia.
A similar table of