CASSIOPEIA, in Astronomy, one of the constellations of the northern hemisphere, situated next to Cepheus. In 1572 there appeared a new star in this constellation, which at first surpassed in magnitude and brightness Jupiter himself; but it diminished by degrees, and at last disappeared at the end of eighteen months. It alarmed all the astronomers of that age, many of whom, as Tycho Brahe, Kepler, Maurolycus, Lyceus, and Gramineus, wrote dissertations on it. Beza the landgrave of Hesse, Rosa, and others, wrote to prove it a comet, affirming that it was the same which had appeared to the Magi at the birth of Jesus Christ, and that it came to declare his second coming: they were answered on this subject by Tycho.