For decades, scientists believed the Moon formed over months or years as debris from a planet-sized collision slowly gathered together.
However, a study in The Astrophysical Journal Letters led by researchers at the Southwest Research Institute and the University of Arizona suggests the Moon may have formed nearly intact in just five hours.
Key Takeaways
- Rethinking Planet Strength: Previous models treated colliding worlds as liquids due to extreme heat. The new simulations account for temperature-dependent structural strength, showing that cooler, solid rock behaves drastically differently during impact.
- Instant Formation: When realistic geologic strength is included, certain collision scenarios don't create a slow-building debris ring—instead, an intact Moon emerges almost immediately.
- Timing & Composition Clues: Factoring in internal temperatures could help scientists pinpoint exactly when the collision occurred and explain why Earth and the Moon share nearly identical chemical compositions.
