The most amusing thing about this marvelous catalog is that Messier was never particularly interested in these objects. His thing was comets, the hot topic in astronomy in the 1750s.

Fifty years earlier, Edmond Halley had predicted that a bright comet seen in 1682 would return to Earth in 1758, and Messier spent 18 months at his telescope, determined to be the first to find it. Unfortunately, he was scooped by a German farmer who made the first sighting of Comet Halley on Christmas night in 1758. Messier was second, finding the comet a month later.

While he was at his telescope earlier that August, however, Messier had spotted another fuzzy patch that looked like it could've been a new comet. But after a few weeks of observation, he saw that the object stayed in exactly the same place in the sky—an impossible feat for a comet. Messier realized he had been duped, and began to build a list of all the other fuzzy objects that might be mistaken for comets. The object he'd seen first became the first object in his catalog, M1, later to be named the Crab Nebula. To his credit, Messier went on to discover 15 bona fide comets; but it his catalog, first published in 1771, that ended up making him famous.

So exactly what celestial wonders do we find in the Messier catalog? They fall into six major categories: 29 spiral galaxies, 8 elliptical galaxies, 29 globular star clusters, 30 open star clusters, 4 planetary nebulae, and 7 diffuse nebulae.