Overview
- Researchers from the Max Planck Institute for Solar System Research and the University of Chicago measured iron isotopes in 15 Earth samples and six Apollo lunar samples with unprecedented precision.
- After correcting lunar data for cosmic‑ray effects, the iron isotope signatures of Earth and Moon were found to be indistinguishable, reinforcing prior similarities across multiple elements.
- By combining iron results with chromium, molybdenum and zirconium constraints, the team used backward mass‑balance models to test viable Earth–Theia collision scenarios.
- The preferred solutions place Theia in the inner Solar System, likely interior to Earth's orbit, and indicate an isotopic mix that does not match known meteorite groups.
- The findings suggest much of the iron in Earth's mantle arrived after core formation, possibly via Theia, while outside experts note uncertainties that require further modeling and new samples.