A large spiral galaxy, visible to the unaided eye as a misty patch in the constellation Andromeda. It lies at a distance of 2.3 million light years and is the largest member of the Local Group, with a mass of 300 billion solar masses. It is believed that our own Milky Way Galaxy is similar to, though it has only half the mass of, the Andromeda Galaxy. The spiral structure is not easy to see since the galaxy is almost edge-on, the disc being tilted at an angle of only 13í to the line of sight. In a small telescope, only the small central nucleus is visible though the fainter spiral arms actually extend over three degrees of sky - more than six times the apparent diameter of the Moon. Several dwarf galaxies are in orbit around the Andromeda Galaxy, notably M32 and NGC 205.
Historically, it was the first object whose extragalactic nature was recognized, and it is the most distant object visible to the naked eye.
