Andromeda is moving fast! Well in terms of science, not people years. Within 5 billion years it will be colliding with the Milky Way. Of course by then the Sun will be a white dwarf so it won't matter much to the Earth.
T.J. Cox and Avi Loeb have given science fiction writers enough fodder for years of stories with a recent report for the Harvard-Smithsonian Center for Astrophysics.
Andromeda's galaxy is 2.5 million light years away from the Milky Way. We're 25,000 light years away from the Milky Way ourselves. By the time the collision occurs the Sun will have heated and dried out the oceans.
Loeb is quoted as joking, "This is the first paper in my publication record that has a chance of being cited five billion years from now."
I think we have a bit of time on our hands to prepare for this one.