<P> When Cepheus' proud wife Cassiopeia foolishly boasted that Andromeda was more beautiful than the Nereids, not only the sea - nymphs themselves but also Poseidon was angered . Thus, the sea god sent a flood and a sea monster Cetus to attack the Aethiopian land . Cepheus and Cassiopeia then consulted a wise oracle of Ammon (identified with Zeus), at the oasis of Siwa in the Libyan desert, who declared that the calamity would not be brought to an end until their daughter Andromeda was offered up to the monster . The king chained the princess to a rock by the shore at the insistence of his people to be devoured by Cetus . </P> <P> Andromeda was saved from this fate when Perseus, flying home with his trophy (i.e. head of Medusa), had passed by the kingdom of Cepheus and noticed that a girl of wonderful beauty was chained to a rock by the seashore . Perseus fell in love with her at first sight and undertook to slay the monster if she would promise to marry him; or, in a slightly different version, he approached her father Cepheus and won an equivalent promise from him . The hero then proceeded to kill the monster with his sword or sickle (or else turned it to stone by showing it the Gorgon's head). Perseus washed off his blood in the spring near the city of Joppa which later became red water, because of his blood . </P> <P> Cepheus and Cassiopeia allowed Perseus to become Andromeda's husband after he used Medusa's head to turn Phineus and his men to stone for plotting against him . According to Hyginus, the betrothed of Andromeda was named Agenor . After spending a year or so at the court of his father - in - law, Perseus finally set off for Seriphos with his wife . Since Cepheus had no heir of his own, the departing couple allowed him to adopt their first - born child, Perses, who was destined to give his name to the Persians . Cepheus was later made into the constellation Cepheus . </P>

Who is cassiopeia in the gorgon's head