Scientists once believed Theia left no chemical trail after vanishing billions of years ago.
Astronomers in France, Germany, and the United States now study ancient lunar and terrestrial rocks to track Theia’s birthplace.
Researchers propose that the long-lost planet formed much nearer to the Sun than earlier theories suggested.
They argue that Theia likely emerged from the inner Solar System before colliding with early Earth.
Scientists maintain that Theia struck the young planet about 4.5 billion years ago.
That impact scattered debris that created the Moon and placed Theia’s material in both worlds.
The giant impact theory has circulated for over 50 years, beginning with early Apollo sample analysis.
Theia’s disappearance erased direct chemical evidence, making its composition and origin difficult to identify.
Astronomers hope new methods can clarify the nature of the vanished impactor.
Experts describe this research as an opportunity to reconstruct conditions from Earth’s earliest era.
Jake Foster from the Royal Observatory Greenwich says the study pinpoints Theia’s birth region with notable accuracy.
He notes that scientists can trace a planet that vanished 4.5 billion years ago.
Tracing a Lost World Through Ancient Signatures
Researchers examined Earth rocks and Apollo mission samples to analyse their isotopes.
These isotopes act as chemical markers that reveal each object’s formation environment.
Scientists already recognise that Earth and Moon rocks share nearly identical metal isotope ratios.
This similarity has complicated efforts to separate original Earth material from Theia’s remnants.
The new study attempts to reconstruct Theia’s properties by analysing multiple isotopic systems.
The team tested isotopes of iron, chromium, zirconium, and molybdenum to model potential early-Earth scenarios.
They generated hundreds of simulations that compared possible Earth–Theia combinations.
These models revealed which mixtures could produce the isotopic signatures found today.
Materials nearer the Sun formed under different temperatures than those farther away.
These temperature differences created distinct isotopic patterns across Solar System regions.
By analysing these variations, researchers concluded Theia formed even closer to the Sun than early Earth.
Some earlier studies proposed that Theia originated farther from the Sun, but new data challenges that view.
Expanding the Picture of Planetary Beginnings
Scientists believe this analysis offers a clearer understanding of early planetary evolution.
They expect the findings to guide new research into how planets accumulate matter and collide.
Researchers say these results may refine models of early Solar System development.
Astronomers emphasise that understanding Theia’s origin helps explain the formation of Earth and the Moon.
This study shows how ancient samples can reveal the history of vanished worlds.
The work demonstrates how isotopic signatures unlock clues about early planetary environments.
Experts hope future missions will provide more samples to test these conclusions.
Researchers aim to expand this approach to study other early Solar System bodies.
They believe that tracing Theia’s past strengthens knowledge of planetary growth and transformation.
The findings encourage new efforts to uncover hidden chapters of Solar System history.
