in Greek mythology, the wife of Cepheus, and mother of Andromeda; in astronomy, a constellation of the northern hemisphere, mentioned by Eudoxus (4th century B.C.) and Aratus (3rd century B.C.). Ptolemy catalogued 13 stars in this constellation, Tycho Brahe 46, and Hevelius 37.37. Its most interesting stars are: - Nova Cassiopeiae, a "new" star, which burst out with extraordinary brilliancy in 1572, when it was observed by Tycho Brahe,but gradually diminished in brightness, ultimately vanishing in about eighteen months; a-Cassiopeiae and R-Cassiopeiae are variable stars, the former irregular, the latter having a long period; n-Cassiopeiae, a binary star, having components of magnitudes 31and 7-1; a-Cassiopeiae, a double star, one being white and of magnitude 5, the other blue and of magnitude 71.