“The Andromeda Galaxy is approaching the Milky Way at about 100 to 140 kilometres per second (62 to 87 mi/s) (400 lightyears every million years),[61] so it is one of the few blue-shifted galaxies” (wikipedia)
Blue. I was wrong in my former statement. Mea culpa!
Something I learned during this was that the theory of why the galaxies collide, even though they are said to be expanding away from each other, is that it is like a cosmic entanglement. Let them get a little too close, while on adjacent trajectories, and they will tend to merge/collide/crash.
Apparently the reason they do this, is because of gravity. However, there is not enough mass in the galaxies to exert such a pull. So.... dark matter. A fudge factor for explaining a process we don’t fully understand.