Collisions happen on different scales. Particles collide. Squirrels accidentally run into each other. Rams butt heads. Tectonic plates shift against each other. There's a lot going on. But in this photo a dwarf galaxy and spiral galaxy are smooshing into each other. And galaxies are kind of huge.
About 60 million light years from Earth, NASA's Chandra X-ray Observatory shows multimillion-degree gas that was probably caused by the collision of a dwarf galaxy and a larger galaxy, NGC 1232. This would be the first time NASA has documented such a collision with X-rays. In the photo, the collision is causing a shock wave, producing the hot gas. From the data currently available, though, it is unclear if the gas is distributed on a flat plain or spread uniformly in all directions. The collision could last for about 50 million years, so there's time to study it in full. But these celestial bodies are definitely on the move. [NASA]