Some time ago, I read an article about the fact that the galaxy M31 probably collided with another galaxy once. If you look at the image, you will see a geometrically completely different arrangement of clouds on the right side of the galaxy than on the left side. I almost want to say: The collision is still going on. It may just be a bad photo, but on the right I just see a smaller spiral galaxy similar to the Milky Way. The same fate awaits us in 3.9-4.5 billion years