Here’s what’s in store for our galaxy in 4 billion years:
That neighboring galaxy is the Andromeda Galaxy. Today it’s 2.5 million light years away, which is 2 x 1019 km (no big deal).
The stars in both galaxies are really far apart. That means the stars won’t be collide with each other. BUT, gravity will slingshot lots of the stars all over the places. Some of them will get ejected from their galaxies, and the other ones will get new random orbits.
Because it’s fun, here are some other video simulations of this future galaxy collision: