Jean-Dominique Maraldi discovered the cluster in 1746 while observing a comet. Messier later added it to his catalog of objects that could be confused with comets—the practical observing list that accidentally became one of astronomy’s most famous tours of the deep sky.
M2 lies roughly 37,000 light-years away in Aquarius and spans more than 150 light-years. Like other globular clusters, its stars crowd much more densely toward the center, producing the bright core and fading halo that observers can compare directly with other globulars.
The contrast between discovery and reality is part of the pleasure. To an 18th-century comet hunter it was a persistent fuzzy nuisance. To us it is an ancient gravitational system containing a stellar population on a scale no single glance through the telescope can resolve.
Sources: NASA Hubble Messier Catalog, “Messier 2.”
