Cassiopeia is a
constellation in the northern sky, named after the vain queen
Cassiopeia in
Greek mythology, who boasted about her unrivalled beauty. Cassiopeia was one of the 48 constellations listed by the 2nd-century Greek astronomer
Ptolemy, and it remains one of the 88 modern constellations today. It is easily recognizable due to its distinctive 'M' shape when in upper culmination but in higher northern locations when near lower culminations in spring and summer it has a 'W' shape, formed by five bright stars. It is bordered by
Andromeda to the south,
Perseus to the southeast, and
Cepheus to the north. It is opposite the
Big Dipper. In northern locations above 34ºN latitude it is visible year-round and in the (sub)tropics it can be seen at its clearest from September to early November in its characteristic 'M' shape. Even in low southern latitudes below 25ºS it can be seen low in the North.