Mass: 300 to 400 billion solar mass (approximately the mass as the Milky Way Galaxy, if not less)
Size: approximately 228,000 light years in length of the disk, and 100,000 light years high (larger than the Milky Way Galaxy)
Visual Magnitude: 3.4
Other Names: Messier 31 (M31), NBC 224, The Little Cloud, The Great Nebula
The Andromeda Galaxy is the nearest spiral galaxy to the Milky Way (2.5~2.9 million light years away). It is also said to be the largest of the 30 galaxies in the Local Group, containing up to a trillion stars. It can be seen with the naked eye from planet Earth.
It was first found by Abd Al Rahman Al Sufi, a Persian astronomer, in A.D. 964. He described the Andromeda as “The Little Cloud.
The Andromeda Galaxy was named after the mythical princess Andromeda, after being spotted in the Andromeda Constellation.
Studies say that the Andromeda Galaxy may have two nuclei, and this may be due to another galaxy that was cannibalized a long time ago, or it may be that there is a single core partly obscured by dust.
What I find interesting is that the Andromeda Galaxy is predicted to collide with the Milky Way Galaxy in approximately 4.5 billion years from now- but it most likely will not effect the Earth in any way, we will be long gone by then, and the human species itself may be extinct as well.