Andromeda Galaxy (aka M31 or NGC224) is a spiral galaxy approximately 2.5 million light years away from Earth. It is the nearest spiral galaxy to our Milky Way, although there are some other galaxies closer to us, but not spiral (like Magellanic Clouds). As one can easy guess the galaxy can be seen in Andromeda constellation. SST observations revealed that M31 contains over one trillion stars (1012) – this is the largest galaxy in our Local Group. Andromeda Galaxy is moving towards us and in about 4.5 billion years both galaxies will collide and eventually merge into large elliptical galaxy.
The galaxy itself can be viewed with naked eye. Its apparent magnitude is about 3.5, but it covers quite a large area in the sky. The galaxy core is quite compact – core apparent diameter is the same as the Moon apparent diameter. But the external arms are spread 3 degrees wide, so it is 6 times more than Moon diameter. However only the core is visible with naked eye, to view the arms you will need good bino or telescope.
Picture above is only one 10 minutes exposure I made last night. The galaxy has not been my target, but I needed to rotate telescope through the whole sky and decided to spend few minutes in this place. In the picture bottom there is M110 galaxy, and above M31 there is NGC206 star cloud. NGC206 is the richest and largest star formation region in our Local Group of galaxies. Below you will find the crop of the galaxy center.