The Milky Way is known to have been involved in two other massive galactic mergers. It absorbed a dwarf galaxy called Gaia-Sausage-Enceladus about 1.8 billion years after the LKH merger. And over the past approximately 6 billion years it has been combining with the Sagittarius dwarf galaxy. The Milky Way, a large and spiral-shaped galaxy that is home to hundreds of billions of stars including our sun, has taken a long and complicated path to achieve its current dimensions, as illustrated by new research documenting a milestone event early in its history.
Scientists observing clusters of stars congregated near the Milky Way's center 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.
