- How to find and observe M31 (TOTS#1) (eyesonthesky.com)
Messier 31 is the closest spiral galaxy to our own Milky Way galaxy. It is over 2 million light years away, so the photons reaching your eye in a telescope tonight left that galaxy some 2+ million years ago, just before the time of homo erectus. The Andromeda galaxy is on a collision course with our own, and the two will merge in about 4 billion years.
