Cassiopeia is one of the most recognizable constellations in the night sky, and being circumpolar can be seen all year round from northern latitudes, as well as from some regions in the Southern hemisphere (-20°) in late spring. This beautiful constellation is most noted for its asterism of five stars which form a giant “M” or “W” as it rotates around the north star Polaris throughout a 24 hour period. Of course, we can only see its night time rotation as the sun blocks our view during the daytime. Throughout the year Cassiopeia often appears as a “W” in the Spring and Summer, and as a “M” in Autumn and Winter.
Cassiopeia is named after a vain Ethiopian queen from Greek mythology, and is surrounded in the night sky by a family of constellations associated with the legend of Perseus, including the hero’s winged horse Pegasus, the queen’s husband Cepheus, her daughter Andromeda, and the sea monster Cetus.
Cassiopeia, mother of Andromeda, was a woman who prized vanity above respect for the Gods, which in ancient Greece was not the wisest of decisions for our self-absorbed heroine. She even boasted that her beauty, and that of her daughter Andromeda was greater than that of the Nereids (sea nymphs) and so, naturally, the fabled sea god Poseidon himself took offense and sent a sea monster (Cetus) to ravage their kingdom. Perseus on his winged-horse Pegasus subsequently rescued Andromeda from Cetus, whom her father (Cepheus) and mother (Cassiopeia) tied to a rock to appease the monster, and so Poseidon decided to punish Cassiopeia all the same by tying her to a chair and placing her in the heavens where she still circles the northern sky, spending half her time upside-down.
We usually associate Cassiopeia with its five main luminous stars which make up the majority of the constellation, although there are actually 53 Bayer/Flamsteed designated stars:
– Alpha Cassiopeia (Schedar) is an orange giant who’s name literally translates into the word ‘breasts’, marking the location of the queen’s heart. The star is located about 280 light years from earth.
– Beta Cassiopeia (Caph) is a yellow white star that is around 50 light years from Earth. The name Caph translates into the word ‘hand.’ Caph is almost 30 times brighter than our own sun, and nearly 4 times the size.
– Gamma Cassiopeia is the central most star in the traditional ‘W’ shape of the constellation. This blue star is located nearly 600 light years from us, and has a mass 15 times greater than our sun.
– Delta Cassiopeia (Ruchbah) is a binary star system settled 100 light years from home, and translates into the ‘knee.’
–Epsilon Cassiopeia (Segin) is a blue white giant, while other stars in the constellation which help form the structure we know so well include Achird, Zeta Cassiopeia, Rho Cassiopeia, and V509 Cassiopeia.
Notable Deep Sky Objects
If you own a decent telescope, there is a plethora of deep sky objects that warrant a mention and are there for your viewing pleasure. Cassiopeia lies in a phenomenal Milky Way star field, so the objects seen in this constellation are nothing short of impressive. Two super-nova remnants can be seen in this field, including Cassiopeia A, and the aftermath of Tycho’s Star. Cassiopeia A is recognized as the brightest radio source in the sky, excluding the solar system. Other notable objects in the field include the Pacman Nebula, Messier 52/103, the White Rose Cluster, and more. So, let’s take a moment to raise our glass to one of the most self-centered individual to ever grace Greek mythology, and give toast to the Queen of Vanity for making this beautiful constellation possible.