M 31 is the nearest large galaxy next to our Milky Way, and is about two times larger than our home galaxy.
The distance between them is 2.5 mill. light-years, and they are the biggest members of the "Local Group" of galaxies, bound together gravitationally.
Two small satellite galaxies to M 31 are also visible on the image, M 110 to the upper right, and M 32 near the lower left edge of the galaxy.
Under dark and transparent conditions M 31 can be seen as a fuzzy patch with the naked eyes.
Because of its size I had to make a mosaic out of six separate panels.