Did the Milky Way form by slowly accreting matter, or by devouring its neighboring galaxies? At last, we're uncovering our own history.

Did the Milky Way form by slowly accreting matter or by devouring its neighboring galaxies? At last, we’re uncovering our own history.

Key Takeaways

  • Although the Milky Way has been around for more than 90% of the Universe’s history, we still don’t know how it grew to be its present size.

  • Two processes are both expected to contribute: mergers with other, smaller galaxies and gravitational growth by absorbing intergalactic matter.

  • By examining the Milky Way’s globular clusters, we can identify at least 5 galactic mergers in our past. “The Kraken,” 11 billion years ago, was the largest.