Messier 99, also known as M99, is a spiral galaxy located in the constellation Coma Berenices. It is approximately 45 million light-years away from Earth and is part of the Virgo Cluster, a group of galaxies that are gravitationally bound together. Discovered by the French astronomer Pierre Méchain in 1781, M99 is notable for its bright, well-defined spiral arms. It has a diameter of about 100,000 light-years and contains a significant number of stars, gas, and dust, making it an interesting object for astronomers studying galaxy formation and evolution.