Messier 55 is a globular cluster located in the constellation Sagittarius. It is approximately 19,000 light-years away from Earth and contains hundreds of thousands of stars. This cluster is notable for its relatively loose structure compared to other globular clusters, making it easier to observe. Discovered by Jean Philippe Loys de Chéseaux in 1746, Messier 55 was later included in the Messier catalog by Charles Messier in 1771. It has an apparent magnitude of about 6.3, which means it can be seen with the naked eye under dark skies.