English: Simulation of interacting galaxies, shortly before fly-by. The dotted curves show the motion of the galactic centres. The simulation uses a restricted N-body model, that means the galactic centres act as attractors and the stars only as test particles. Although this simple method is of no scientific use, it shows the major effects of a galactic encounter. The same applies for Image:Interacting Galaxies 2.png and Image:Interacting Galaxies 3.png, which show later stages of the simulation.