A constellation of the northern sky, representing Queen Cassiopeia of Greek mythology. Its brightest stars are Alpha (Schedar) and Beta Cassiopeiae (Caph). Gamma Cassiopeiae is a shell star that can vary unpredictably between about magnitudes 3.0 and 1.6. M52 is a prominent open cluster, near which lies the strong radio source Cassiopeia A. The supernova now known as Tycho’s Star flared up near Kappa Cassiopeiae in 1572.