Observing Cassiopeia the Queen
The North Circumpolar Constellation Shaped Like a "W"
Cassiopeia the Queen is a an average-sized constellation near Polaris often used in pointing the way to the Andromeda Galaxy.
In mythology, Cassiopeia was the Queen married to King Cepheus, who looks like a house-shaped object next to her in the sky. Cassiopeia appears to be sitting on a chair, which gives us the bent shape that looks like a "W". The big "W" in the sky is easy for observers to spot because of its fairly bright stars. In the fall, the rotation of the stars around the pole means that it takes on more of an "M" appearance.
Finding Cassiopeia in the Sky
Cassiopeia is a North Circumpolar constellation, which means that observers in the north can view it any night of the year because it never sets. It lies on the opposite side of Polaris from the Big Dipper. The stretched-out W shape of Cassiopeia itself is surrounded by dim, less noticeable constellations, making it the biggest landmark in this portion of sky.
The Stars of Cassiopeia
The brightest star of Cassiopeia is the star at the center of the W shape. This star is magnitude 2.15 Navi, or Gamma Cassiopeiae. It lies a great distance from Earth, at 613 light-years away. The other two stars that make up the right side of the W (the second "V", if you will) are of similar brightness to Navi. The one at the bottom is magnitude 2.24 Schedar, or Alpha Cassiopeiae. It lies 229 light-years distant. The other star on the right is magnitude 2.27 Caph, or Beta Cassiopeiae. It lies 54 light-years away. These three stars have very different distances from us, yet they are all of a similar magnitude, revealing that the physical characteristics of the stars themselves must be quite diverse.
The last two stars of the "W" that make up the top and bottom of the first line are Epsilon and Delta Cassiopeiae. Epsilon is the dimmest of all five, at magnitude 3.35. it lies 442 light-years away. Delta, or Ruchbah, is a magnitude 2.66 and lies 99 light-years distant.
It is common to use the brighter "V" in the W shape of Cassiopeia to find the Andromeda Galaxy. The V-shape nearly points the way. For more, read the article about Andromeda.
Deep-Sky Targets in the Queen
Cassiopeia lies along the Milky Way, providing a number of star clusters for viewing, including two Messier objects.
The first object can be found extending outward from the last line used to draw the "W". From the stars Alpha to Beta, draw a line continuing up for about the same distance. (Alpha and Beta are five degrees apart, Beta and star cluster M52 are six degrees apart.) M52 is magnitude 6.9 star cluster. This dense grouping is only a half degree away from the Bubble Nebula, NGC 7635. The nebula can be difficult to see due to a 7th-magnitude star nearby.
The other Messier object in Cassiopeia is M103, located just one degree from Delta Cassiopeiae. This 7.4 magnitude cluster is considered a "poor" cluster because it is loose and not well-defined. It can be glimpsed in binoculars; telescopes may confuse it with nearby star groups.
One of those nearby star groups to M103 is the ET Cluster, NGC 457 at magnitude 6.4. About three degrees away and on the other side of Zeta, NGC 457 can look like a little alien if you use your imagination. Picture the two brighter stars as eyes and then trace out his arms and body.
