Rust has been detected on the Moon, and surprisingly, Earth may be the source of this chemical transformation. Recent research finds that oxygen escaping from Earth likely drives the oxidation of lunar iron into hematite near the poles. Even if iron and oxygen were present, hydrogen in the solar wind normally cancels oxidation, making rust formation highly unlikely on the Moon. The experiments confirmed that oxygen ions from Earth could oxidize metallic iron into hematite, supporting the idea that Earth wind drives lunar rusting. Implications for lunar scienceThe formation of hematite on the Moon shows a chemical exchange between Earth and the Moon over billions of years.