Our Milky Way galaxy gobbled up a smaller galaxy about 11.8 billion years ago, scientists find

Scientists observing clusters of stars congregated near the Milky Way's centre have discovered evidence that our galaxy swallowed a smaller galaxy roughly 11.8 billion years ago, when the universe was less than 15 per cent of its current age. The event represents the Milky Way's earliest-known galactic merger and shows how it grew not only ​by forming its own stars but by merging with smaller galaxies caught in ​its gravitational pull.

The smaller galaxy is classified as a dwarf galaxy, differentiating it from larger galaxies like the Milky Way. The researchers estimate that it contained stars with a mass equivalent to 500 million times that of the sun ​at the time of the merger, about a quarter the size of what the Milky Way was at the ⁠time.