Messier 15, also known as M15, is a globular cluster located in the constellation Pegasus. It is approximately 33,600 light-years away from Earth and contains around 100,000 stars. M15 is one of the densest globular clusters known, with a core that is particularly rich in stars. Discovered by Jean-Dominique Maraldi in 1746, M15 was later cataloged by Charles Messier in 1764. The cluster is notable for its bright core and is home to several variable stars and a planetary nebula, Pease 1. M15 is a popular target for amateur astronomers due to its brightness and compact appearance.