Andromeda Galaxy, also known as M-31, is a large spiral galaxy, very similar in appearance to, and slightly larger than, our own Galaxy located about 2.5 million light years away. Its diameter is approximately 200,000 light-years and as our nearest neighbor, Andromeda is extremely large on the sky.
Andromeda Galaxy is visible to the naked eye, although we can only see the bright inner bulge. It has been known since at least the year 964AD, when Persian astronomer Al-Sufi described it as a `little cloud’ in the Book of the Fixed Stars. The first description of the object based on telescopic observation was given by German astronomer Simon Marius on December 15, 1612, describing the sight as “like a candle seen at night through a horn” (referring to horn lanterns, then common).
The Andromeda Galaxy is approaching the Milky Way at about 190 miles per second due to gravitational forces and are expected to collide in about 3.75 or 4.5 billion years. Stars inside each galaxy are so far apart that they will not collide with other stars during the encounter. However, the stars will be thrown into different orbits around the new galactic center.
The photo was shot with a 10-minute exposure using a SBIG ST-8300C one-shot color CCD connected to a Takahashi 6″ refractor, located at the New Mexico Skies observatory. The Andromeda galaxy (M31) is at RA: 0h 42.7m; Dec: 41o 16′ north.