Triangulum, Casseopia, and Andromeda

Last night the sky was clear so Logan and I pulled out the starmap and flashlight and did some observing from the backyard. Recently I've been focusing on the Southwestern horizon simply because of the lack of line of sight obstructions, but decided to check out the Northeast sky. I'm really glad I did! Here are the most interesting objects we observed last night.

Cassiopia
The first constellation that caught my eye was Cassiopia (click for larger):As you can see, Cassiopia has a distinct "W" shape, making it easy to find in the sky. The leading star, alpha Cas is an irregular variable star and together with its ninth magnitude neighbor forms an optical double star (not physically related). An irregular variable star is a star which goes through significant changes in it's luminosity which show no regular periodicity. Gamma Cas is an rapidly spinning unstable blue subgiant with a decretion disk around its bulging equator. Another near variable star is rho Cas. Its variable period is unknown and it is surrounded by lots of nebula and open clusters.

The Andromeda Galaxy (M31)

Near Cassiopia in the Andromeda constellation is Messier Object 31, the Andromeda Galaxy. M31 is the largest of our near galactic neighbors, composing the Local Group together with its companions. The Spitzer Space Telescope recently estimated the number of stars in M31 to be approximately one trillion stars, much greater than in our own Milky Way.

To the naked eye, M31 appears to be quite small because only the central part is readily visibly, but the full angular diameter is actually seven times that of the full moon. M31 is one of the only galaxies that appears blue-shifted to us due to the fact that it is approaching the Milky Way at a speed of about 300 kilometers a second. It is possible that in about 3 billion years M31 and the Milky Way will collide to form a giant elliptical galaxy. It tripped me out last night to look at M31 and realize it's flying straight for us. It's really pretty amazing.

The Triangulum Galaxy (M33)

Also near Cassiopia in the Triangulum constellation is M33, the Triangulum Galaxy. M33 is approximately three million light years away from the Milky Way and is the third largest galaxy in the Local Group. The Triangulum Galaxy is the faintest naked-eye object visible in the night sky because it's considerable brightness is (more or less) evenly distrubuted over an area of the sky equal to four full moons. I guess last night we got really lucky!