The constellation of Andromeda represents the daughter of King Cepheus and Queen Cassiopeia of Ethiopia and the wife of Perseus. The constellation was first outlined by Ptolemy in the second century.
Cassiopeia was a vain woman and claimed she was the most beautiful woman in the world, even more beautiful than the sea nymphs (nereids). The goddesses were so offended that they complained to Poseidon, the god of the sea to seek vengeance. Poseidon released the kracken, Cetus a monstrous creature upon the kingdom.
Cepheus in order to protect his lands consulted three wise witches who had the ability of foresight. They told him to sacrifice Andromeda. Cepheus then had Andromeda chained to the sea cliff awaiting the arrival of Cetus.
Perseus was passing by on the winged horse Pegasus and spotted Andromeda’s plight. Down he swooped and saved the princess by turning Cetus to stone using the head of Medusa.