Andromeda constellation. Optical image of the constellation Andromeda, a northern constellation named after the princess Andromeda in Greek mythology. The Andromeda Galaxy (M31) is the fuzzy object above centre. This large spiral galaxy is around 2.5 million light years away. Andromeda was the daughter of Cepheus, the King, and Cassiopeia, the Queen. Sometimes called the Chained Maiden, Andromeda was chained to a rock and left to the sea monster Cetus to appease the gods. She was rescued by Perseus.