The Hubble Space Telescope has discovered two massive star clusters that are colliding in space, NASA announced.

The clusters, located in the Tarantula Nebula, are about 170,000 light years away from Earth. They are inside a the Large Magellanic Cloud, a small galaxy that orbits our own Milky Way.

Scientists believe that one of the clusters is about a million years older than the second. They believe that the gravitational interaction between the two clusters created a lot of so-called “runaway stars,” or stars that are moving away from the region they originated in at a high rate of speed.