10. M31, the Andromeda galaxy.  Andromeda is our nearest large neighbor galaxy.  This is another very large object in the night sky.  If it was a lot brighter, you could easily just look up and see it, about three times larger than the moon.  The smaller galaxy is M110 which is a satellite galaxy of Andromeda.

As you look at this picture, think of it in three layers.  Virtually all of the pin point stars you see in this picture are part of our own Milky Way galaxy.  So the first, nearest layer, is a star field that is part of the Milky Way.  The next middle layer is nothing but mostly empty space.  Then in the third farthest layer is the Andromeda galaxy and the satellite galaxy M110 which orbits Andromeda.  So we're looking first through a nearby star field, then through a bunch of empty space, then seeing the Andromeda galaxy.

Not surprisingly, the Andromeda galaxy is located in the constellation Andromeda.  Below the constellation Cassiopeia, the big "W".