Messier 54 is a globular cluster located in the constellation Sagittarius. It is approximately 87,000 light-years away from Earth and is one of the most distant globular clusters known. Discovered by Charles Messier in 1778, it contains hundreds of thousands of stars tightly packed together, giving it a bright and dense appearance. This cluster is notable for its unique composition, as it is believed to have formed from the remnants of a dwarf galaxy that merged with the Milky Way. Messier 54 is also associated with the Sagittarius Dwarf Spheroidal Galaxy, providing insights into the history of galaxy formation and evolution.