The Pegasus Galaxy, also known as M31, is a spiral galaxy located approximately 2.5 million light-years from Earth in the constellation Pegasus. It is one of the closest galaxies to our Milky Way and is part of the Local Group, which includes other galaxies like the Andromeda Galaxy and the Triangulum Galaxy. This galaxy is notable for its large size, containing around one trillion stars. It has a diameter of about 220,000 light-years, making it one of the largest galaxies visible from Earth. The Pegasus Galaxy is also a popular target for astronomers studying galaxy formation and evolution.