Messier In France during the 1700's, Charles Messier was hunting for comets. He kept finding fuzzy things which weren't comets, so he made a list of them so he wouldn't waste his time on them again. The list grew to about 110 objects , and includes most of the finest star clusters, galaxies, and nebulae visible from the northern hemisphere. People have actually been doing it since 1977 .
Different people have different reasons.
Some like the sense of accomplishment. Finding all 110 objects in a single night isn't easy, and you have to know the objects and their locations very well to do it. In addition, the 110 objects represent a wide sample of the objects in the sky. One can compare objects of the various types to each other, and gain a better understanding of how the universe is put together. There' s also a kind of camaraderie which builds up between observers who are lunatic enough to stay up all night collecting faint fuzzies, and Marathon nights can be social occasions.