Galaxies are not solid but are composed of stars and gas that can be disrupted by a near-collision. Here, a large amount of gas from one galaxy has been pulled into a streamer by the gravitational force of another. The streamer consists of gas that would normally not be visible; it has been lit by bright, newborn stars. The streamer is not stable. As the galaxies move apart, the stars that form it will return to the larger galaxy.
