What exactly happens when two large galaxies collide with one another? Any image of a galaxy collision captures only one instant in a collision process lasting a billion-years ? a gradual waltz of stars and gas choreographed by gravity. This visualisation of a galaxy collision created by a supercomputer simulation shows the entire collision sequence, and compares the different stages of the collision with different interacting galaxy pairs observed by the NASA/ESA Hubble Space Telescope. With this combination of research simulations and high resolution observations, these titanic crashes can be better understood.Crossfades between different merging galaxies from a collection of fifty nine new images of colliding galaxies ? the largest collection of Hubble images ever released together. As this astonishing Hubble atlas of interacting galaxies illustrates, galaxy collisions produce a remarkable variety of intricate structures.