Overview
- A peer-reviewed Science paper published November 20 by Hopp and colleagues concludes the Moon-forming impactor originated in the inner Solar System.
- New iron isotope measurements show Earth and the Moon are indistinguishable and align with non‑carbonaceous meteorites that represent inner‑Solar‑System material.
- The team analyzed 15 terrestrial rocks, six Apollo lunar samples, and meteorites, then used mass‑balance calculations to infer Theia’s composition and origin.
- Modeling indicates Theia likely formed closer to the Sun than proto‑Earth, consistent with Earth and Theia being near neighbors during early planet formation.
- The study does not resolve how the giant impact mixed materials or the exact Earth–Theia contributions to the Moon, highlighting the need for further simulations and new samples.