Andromeda galaxy M31, optical image. Andromeda, lying only 2.5 million light years away, is the closest major galaxy to our own. Like our galaxy, the Milky Way, it is a barred spiral galaxy, spiral in form but with a bright band of stars across the centre. With a diameter of 150,000 light years, it is about half as large again as the Milky Way. The older stars towards the centre of the galaxy make its core appear yellow. The two bright objects close to the galaxy are Andromeda磗 two satellite galaxies, M32 bottom centre and M110 just upper left of centre. The galaxy is named after the constellation Andromeda, where it is found.