Final answer:
Galaxy collisions can transform spiral galaxies into elliptical ones, with evidence of such events including disrupted galactic structures and star streams. Astronomical observations, alongside simulations, support the occurrence of these transformative mergers.
Step-by-step explanation:
When two galaxies collide, a complex process occurs that can fundamentally change their structures, leading to the formation of different types of galaxies, notably elliptical galaxies from the mergers of spiral galaxies. These colossal events can be inferred from astronomical observations such as distorted galaxy shapes, tidal tails, and star streams that provide evidence of past interactions.
Elliptical galaxies often form when two or more spiral galaxies collide and merge. The gravitational forces dramatically alter their original shapes, and if the collision is significant enough, their distinct spiral arms can be disrupted to form a more elliptical structure. Over time, the gravitational pull equalizes the distribution of stars and gases, smoothing them into the characteristic ellipsoidal shape of an elliptical galaxy.
Supporting the idea that galaxy collisions sometimes occur, astronomers have discovered a variety of evidence including disturbed galactic structures, bridges of stars and gas between galaxies, and galaxies with double nuclei. Moreover, simulations of galaxy collisions align closely with astronomical observations, further solidifying the role of mergers in galactic evolution.