CASSIOPEIA  , 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 . 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; ri-Cassiopeiae, a binary star, having components of magnitudes 32 and 72; o--Cassiopeiae, a double star, one being white and of magnitude 5, the other blue and of magnitude 71 .