Courtesy of EarthSky
A Clear Voice for Science
Cassiopeia the Queen can be found in the northeast after sunset on September evenings. This constellation has the distinct shape of a W, or M, depending on the time of night you see it. The shape of this constellation makes Cassiopeia’s stars very noticeable.
Cassiopeia represents an ancient Queen of Ethiopia. The entire constellation is also sometimes called Cassiopeia’s Chair, and some old star maps depict the Queen sitting on the Chair, marked by the five brightest stars of this constellation. These stars are Schedar, Caph, Gamma Cassiopeiae, Ruchbah, and Segin.
If you have a dark sky, you can look below Cassiopeia in the northeast on these September evenings for a famous binocular object. This object is called the “Double Cluster” in the constellation Perseus. These are open star clusters, each of which consists of young stars still moving together from the primordial cloud of gas and dust that gave birth to the cluster’s stars. These clusters are famous binocular targets, familiarly known to stargazers as H and Chi Persei.
Stargazers smile when they peer at them through their binoculars, not only because they are beautiful, but also because of their names. They are named from two different alphabets, the Greek and the Roman. Stars have Greek letter names, but most star clusters do not. Johann Bayer (1572-1625) gave Chi Persei – the cluster on the (top? bottom?) – its Greek letter name. Then, it is said, he ran out of Greek letters. That is when he used a Roman letter – the letter H – to name the other cluster.
After midnight, Cassiopeia swings above Polaris, the North Star. Before dawn, she is found in the northwest. However, during the evening hours, Queen Cassiopeia lights up the northeast sky.
Written by EarthSky