Andromeda is a northern
constellation representing the mythological Andromeda, daughter of
Cepheus and
Cassiopeia and later wife of
Perseus, whom
Poseidon chained to a rock to be sacrificed to a sea monster (usually assumed to be
Cetus). Andromeda is one of the 88 modern constellations, and was also one of the 48 listed by
Ptolemy. It is mainly notable as the location of the [Andromeda Galaxy]
?, M31.