Astronomers in France, Germany, and the United States have tracked Theia’s origins using ancient rocks.
Theia vanished billions of years ago, leaving no direct chemical evidence.
Scientists believe Theia collided with early Earth about 4.5 billion years ago.
Debris from the impact formed the Moon, mixing material from both worlds.
Researchers now suggest Theia formed closer to the Sun than early Earth.
The giant impact theory has guided Moon formation studies since Apollo samples arrived.
Jake Foster of the Royal Observatory Greenwich says researchers can pinpoint Theia’s birth despite its disappearance.
He notes the planet completely vaporised, yet isotopes reveal its solar birthplace.
Reverse Engineering Planetary History
Researchers analysed terrestrial rocks and Apollo lunar samples to study isotopes.
These isotopes act as chemical fingerprints of early Solar System formation.
Earth and Moon rocks share nearly identical metal isotope ratios, complicating analysis.
The team separated signals from early Earth and Theia material through isotopic modelling.
They tested iron, chromium, zirconium, and molybdenum isotopes across hundreds of scenarios.
Simulations identified which early-Earth and Theia combinations produce today’s observed isotopic signatures.
Isotopic differences reflect materials forming at varying distances and temperatures from the Sun.
Comparing these patterns revealed Theia likely originated inside Earth’s orbit.
Implications for Planet Formation
The study reshapes understanding of early Solar System dynamics.
Scientists hope the method helps future research on planetary growth and collisions.
The analysis provides insight into how planets evolve in early solar environments.
Astronomers aim to use isotopes to reconstruct histories of other vanished worlds.
This approach may reveal how collisions shape planetary composition and orbit.
Understanding Theia’s origin strengthens knowledge of Moon formation and Earth’s early history.
Researchers plan to expand these techniques to explore additional planetary interactions.
