High in the northeastern sky after sunset is the constellation Cassiopeia. On a clear night during the fall and winter you can watch as it makes its way across the sky. Cassiopeia can be seen a few different ways depending on it’s location in the sky; as it rises it can look like the number three, and as it reaches the meridian – straight overhead – it looks like the letter ‘M’, and the letter ‘E’ as it sets to the northwest later in the season.
There are five stars that make up the letters and numbers I mention in the main constellation of Cassiopeia; Segin, Ksora, Cih, Schedir, and Caph. These five stars resemble the chair in which the queen sits in looking out towards the rim of the Milky Way.
Towards Cassiopeia you can see the faint glow of our Milky Way galaxy as we orbit around the sun and start to look away from the center of our galaxy. We can see it all winter long throughout other constellations as we start to turn away from our summer constellations and the central core of our galaxy. Although not glowing as bright as the summer Milky Way this portion of the sky still contains many stars, clusters, and nebula all shaping that white, almost cloud like band across our night skies.
When astronomers talk about constellations they aren’t just talking about the pattern, or asterism, that represents the shape for which it is named, they are referring to the boundary given by the International Astronomical Union (IAU) (http://www.iau.org). Constellations can contain many different representations by different cultures and can’t be defined as just one single asterism, so these boundaries serve as a way to mark a section of the sky. In reality the constellations seen above are all a matter of perspective, and the stars are all differing in brightness and distance from Earth.
A little mythology about Cassiopeia and how she became a constellation in the sky. She was the queen of Aethiopia, and the wife of Cepheus, King of Aethiopia and the mother of the Princess Andromeda. Cassiopeia, Andromeda, and Cepheus were placed together among the stars as punishment for her boasting that her daughter was more beautiful than the fifty daughters of Nereus, and Doris. Her placement in the sky kept her sitting in her throne for part of the year, and spending the other half of the year clinging to the throne as not to fall off while the constellation orbits the North Celestial Pole.
During these cold months of fall and winter we can watch as she makes her way around the pole as we enjoy the long nights, and the soft glow of our Milky Way. I find the mythology of how the constellations came to be just as interesting as the sights that can be seen within the constellations through a telescope. How the ancient’s saw the stars in the sky, and the hows and whys of how they came to be out of the placement of the stars. Also learning the shapes of the constellations and a little bit of history about them come in handy for remembering their placement in the sky. Enjoy the fall night skies, but be sure to dress warm.
Photo Above: Image of Cassiopeia constellation showing boundary lines provided by the International Astronomical Union
Photo Below: Image of Cassiopeia taken from my back yard by Michael Rector