M 31

The Andromeda galaxy, also known as M 31 or Messier 31, is probably the best known galaxy on the sky. Due to its distance to Earth it is also one of the best studied ones. Located in the Andromeda constellation it is the nearest spiral galaxy to the Milky Way. However, it is not the nearest galaxy overall.

The galaxy, which recived its old name from the mythological princess Andromeda, can be seen on a dark night sky with the naked eye. It is the largest galaxy in the Local Group, which also contains the Milky Way, the Triangulum Galaxy and more than 50 smaller galaxies.