Overview

• Researchers conclude Earth’s chemical signature was fixed no later than about three million years after the Solar System formed, implying an initially dry rocky planet.
• A 53Mn→53Cr isotopic chronometer provided sub–one‑million‑year age precision using data from meteorites and terrestrial rocks.
• The results support a scenario in which a later impact with a water-rich body, Theia, delivered volatiles and contributed to the Moon’s formation.
• The study was led by Pascal M. Kruttasch with co-author Klaus Mezger at the University of Bern and is published in Science Advances.
• The authors urge development of integrated impact and geochemical models that can match the Earth–Moon system’s physical, chemical and isotopic signatures.