The Milky Way's Disc Was Flipped Upside Down 10 Billion Years Ago
Supercomputer simulations presented at NAM 2026 show the Milky Way's disc was flipped by more than 90 degrees after a head-on collision with the Gaia-Sausage-Enceladus dwarf galaxy roughly 10 billion years ago — a finding diagnostic tests on thousands of simulated galaxies now support.