An ancient constellation that is part of the story of Perseus and Andromeda. Cassiopeia was the mother of Andromeda, and because of her boasting that she was more beautiful than the sea nymphs, the Nereids, she was forced by the god Poseidon to sacrifice her daughter to the sea monster Cetus. Also as punishment the image of Cassiopeia was placed in the sky in such a way that during part of the year the queen appears upside down. The constellation is more easily recognized as the letter m or w and can be found in the northern sky all year round.