Writing a sci-fi book, need some assistance with distances and time.?

[northbendriver]

Basically, it takes place in about 200 million years (bear with me) and humanity has long abandoned earth in favor of a new galaxy. Now, the whole plot is that they go back to earth and find that they have been gone so long, a new supercontinent has formed (Pangea Ultima).

In real life, scientists predict that a real Pangea Ultima will form in about 150-200 million years. So what I need is this:

A galaxy or cluster somewhere in the universe that would take 100 million earth years to get to traveling at light speed and if you can, how many light years that would be.
Alternately, if you can come up with a way that a supercontinent could form in the next few hundred thousand years (I don't know, maybe a huge asteroid?), that would save us all the trouble of lightyears and such.

 

[zhuge_liang1]

Either the Andromeda Galaxy at about 2.5 million light years away or the Triangulum Galaxy at about 3 million light years away are probably the best choices since they are the largest and third largest galaxies in the local cluster and therefore have a much higher probability of containing a good number of Earth-like planets.