Messier 91 is a barred spiral galaxy located in the constellation Virgo. It was discovered by the French astronomer Pierre Méchain in 1781 and later included in the Messier Catalog by Charles Messier. This galaxy is approximately 38 million light-years away from Earth and has a diameter of about 100,000 light-years. Messier 91 is notable for its bright core and well-defined spiral arms, which contain numerous stars and nebulae. It is part of the Virgo Cluster, a group of galaxies that includes many other well-known galaxies, such as Messier 87 and Messier 86.