Although galaxy collisions are common, stars in each galaxy are so far apart that collisions between stars are very rare. When two galaxies interact, clouds of gas inside each galaxy may become compressed. Compressing the clouds can cause them to collapse under their own gravity, turning into stars.Click to see full answer. In respect to this, why should galaxy collisions be more common in the past?A) Galaxies were more active in the past and therefore would have collided with each other more frequently. D) Galaxies attracted each other more strongly in the past because they were more massive; they had not yet turned most of their mass into stars and light. what are galaxy collisions? In a galaxy collision, large galaxies absorb smaller galaxies entirely, tearing them apart and incorporating their stars. But when the galaxies are similar in size – like the Milky Way and Andromeda – the close encounter destroys the spiral structure entirely. Likewise, how often do galaxies collide? Lotz’s team found that galaxies gained quite a bit of mass through collisions with other galaxies. Large galaxies merged with each other on average once over the past 9 billion years. Small galaxies were coalescing with large galaxies more frequently.What happens to planets when galaxies collide?Over large periods of time, the two galaxies will gravitationally interact, attracted to each other. As they merge, the stars and planets of one get mixed with the stars and planets of the other, resulting in a larger galaxy with a different structure to either of the originals.