We Can Already See it Coming
As we have noted previously, Andromeda is visible to the naked eye as a hazy patch
(apparent visual magnitude 4.3). Thus, we can already see it coming on its collision course
with us! The projected time to collision between the two galaxies is less than the timescale
for the Sun to become a red giant, so the Earth may still exist then.
Presumably in a couple of billion years the Andromeda Galaxy will be a spectacular
sight in our sky.