Scientists are studying the history of collisions between the Milky Way and other galaxies and the possible consequences of future collisions. These collisions, incidentally, are still occurring
The Milky Way’s halo contains a large group of stars with unusual orbits, many of which are believed to have been engulfed by our galaxy during an event astronomers call the “last major merger.” As the name suggests, this was the last time our galaxy experienced a significant collision with another galaxy—presumably a massive dwarf galaxy that flooded the Milky Way with stars passing very close to our galaxy’s center.