What happens when galaxies collide?
What would happen if two galaxies collided? Is it possible? It is very common for galaxies to collide and interact with other galaxies. In fact, it is now believed that collisions and mergers between galaxies are one of the main elements that drive their evolution in time. Most galaxies probably had interactions with other galaxies since the time they formed. A galaxy is made of roughly 100 billion stars. So you would think that in a head on collision between two galaxies, there would be countless collisions between those stars, right? The fact is that in such a collision, the probability of two stars colliding is almost 0. This is because even though there are an incredibly large number of stars in the galaxies, the density of stars is not very big since the galaxies are extremely big. In other words, the sizes of the stars are very small compared to the average distance between them. This means that if galaxies were made only of stars, and that two of them would go on a head on colli
