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last mo.

Study Finds Only 2% Chance of Milky Way-Andromeda Collision in Five Billion Years

Galaxy motions suggest a 50 percent likelihood of collision by ten billion years, well after the Sun’s expected five-billion-year lifespan.

Three images show different scenarios for how the Milky Way and Andromeda galaxies could interact in the future. At top left, two spiral galaxies pass each other at a large distance. At top right, two spiral galaxies are closer together, their invisible gas halos interacting. The bottom image shows the collision of two spiral galaxies, resulting in an X-shaped patch.
Image
Image: NASA/JPL-Caltech

Overview

  • New simulations incorporating Hubble and Gaia data indicate only a 2 percent chance of a direct Milky Way–Andromeda collision within five billion years.
  • Expanded models raise the probability to roughly 50 percent for a merger within ten billion years, beyond the Sun’s lifecycle.
  • Researchers identify the Large Magellanic Cloud’s gravitational influence as a key factor diverting the Milky Way’s trajectory away from Andromeda.
  • Models forecast an almost certain merger between the Milky Way and the Large Magellanic Cloud within two billion years.
  • Scientists caution that remaining uncertainties in galactic masses, positions and motions leave the ultimate fate of the Milky Way open to further study.