Scientists have long hypothesized that Theia, a vanished planet, collided with Earth to create the Moon.
Astronomers in France, Germany, and the United States analysed ancient lunar and terrestrial rocks to track Theia.
New research suggests Theia formed much closer to the Sun than previously believed.
The giant impact theory proposes that debris from Theia struck Earth 4.5 billion years ago.
The collision ejected material that later coalesced to form the Moon.
Theia’s disappearance erased direct chemical evidence, leaving its origin and composition uncertain for decades.
Jake Foster of the Royal Observatory Greenwich calls the research exciting and precise.
He emphasizes that scientists now trace a planet that vanished 4.5 billion years ago.
Decoding Planetary Fingerprints
The team studied Earth rocks and Apollo lunar samples to examine isotopes.
These isotopes serve as chemical fingerprints revealing formation conditions.
Earth and Moon rocks share nearly identical metal isotope ratios, complicating Theia’s identification.
Researchers applied planetary reverse engineering to separate Earth material from Theia’s remnants.
They analysed isotopes of iron, chromium, zirconium, and molybdenum to model hundreds of early Solar System scenarios.
Simulations tested which combinations could reproduce isotopic patterns seen today.
Materials near the Sun formed under hotter conditions than those farther out.
These conditions created regional differences in isotopic signatures across the Solar System.
Redrawing the Solar System Map
Researchers concluded that Theia most likely originated in the inner Solar System, nearer the Sun than Earth.
Earlier theories suggested Theia formed farther out, but isotope data challenges that assumption.
The team hopes these findings guide future studies on planetary growth, collisions, and evolution.
Scientists believe the approach could improve models of early Solar System dynamics.
The research highlights how ancient rocks can reveal lost planets and their paths.
By tracing Theia’s origin, astronomers gain insights into how planets interact and transform in early solar systems.
This study sets a framework for understanding the violent processes shaping planetary formation billions of years ago.
