In Greek mythology, Andromeda was the daughter of the Aethiopian king Cepheus and his wife Cassiopeia. Cassiopeia's hubris led her to boast that Andromeda was more beautiful than the Nereids, the nymph-daughters of the sea god Nereus, who often accompanied Poseidon.
Poseidon sent a sea monster, Cetus, to ravage the kingdom of Aethiopia as divine punishment. Andromeda was stripped and chained to a rock as a sacrifice to sate the monster. She was saved from death by Perseus, who was returning from having slain the Gorgon Medusa.
Perseus set Andromeda free, and married her in spite of her having been promised to her uncle Phineus. At the wedding a quarrel took place between the rivals, and Phineus was turned to stone by the sight of the Gorgon's head.
Together, Andromeda and Perseus became the ancestors of the family of the Perseidae through the line of their son Perseus. Following Andromeda's death, the goddess Athena honored her by placing her in the sky as a constellation.
Several neighboring constellations - Perseus, Cassiopeia, Cetus and Cepheus - represent characters in the Andromeda myth. The Andromeda constellation also is connected with the constellation Pegasus. Because of its northern declination, the Andromeda constellation is visible only north of 40° south latitude; for observers farther south it lies below the horizon.
[Image: Perseus Cycle 7: The Doom Fulfilled (1888) oil on canvas by Edward Burne-Jones (1833-1898). Today seen in the Southampton City Art Gallery.]