In Greek mythology Andromeda is the daughter of Cepheus and Cassiopeia, king and queen of ancient Ethiopia. Her mother Cassiopeia foolishly boasts that she is more beautiful than the Nereids, a display of hubris by a human that is unacceptable to the gods. To punish the queen for her arrogance, Poseidon floods the Ethiopian coast and sends a sea monster named Cetus to ravage the kingdom's inhabitants. In desperation, King Cepheus consults the oracle of Ammon, who announces that no respite can be found until the king sacrifices his daughter, Andromeda, to the monster. She is thus chained to a rock by the sea to await her death. Perseus is just then flying near the coast of Ethiopia on his winged sandals, having slain the Gorgon Medusa and carrying her severed head, which instantly turns to stone any who look at it. Upon seeing Andromeda bound to the rock, Perseus falls in love with her, and he secures Cepheus' promise of her hand in marriage if he can save her. Perseus kills the monster with the magical sword he had used against Medusa, saving Andromeda. Preparations are then made for their marriage, in spite of her having been previously promised to her uncle, Phineus. Andromeda was never asked for her opinion. At the wedding a quarrel takes place between the rivals, and Perseus is forced to show Medusa's head to Phineus and his allies, turning them to stone. Andromeda follows her husband to his native island of Serifos, where he rescues his mother Danaë. They next go to Argos, where Perseus is the rightful heir to the throne. After accidentally killing Argos' king, his grandfather Acrisius, however, Perseus chooses to become king of neighboring Tiryns instead. Perseus and Andromeda have seven sons: Perses, Alcaeus, Heleus, Mestor, Sthenelus, Electryon, and Cynurus as well as two daughters, Autochthe and Gorgophone. The goddess Athena places Andromeda in the northern sky at her death as the constellation Andromeda, along with Perseus and her parents Cepheus and Cassiopeia, in commemoration of Perseus' bravery in fighting the sea monster Cetus.