Andromeda: even galaxies have error bars
Long-term galaxy simulations depend on uncertain motions and on which nearby galaxies are included. The 2025 and 2026 results should be read as different analyses, not as successive versions of a single perfectly known clock.
Showing both is more useful than replacing one enormous exact number with another. The entry does not infer that the solar system is destroyed on the merger date, or give an impact countdown for individual stars.
Sources & version history
- 2025-06-02 — NASA described a study giving roughly even odds of merger within ten billion years. Source
- 2026-03-24 — A later model found a higher merger probability, with a median near 6.5 billion years. Source