Moon scientists long searched for traces of Theia, a vanished world that left no direct chemical remains.
Researchers in France, Germany, and the United States analysed ancient lunar and Earth rocks to trace Theia’s birthplace.
New findings suggest this lost planet formed far closer to the Sun than earlier theories claimed.
Experts now argue that Theia, the body that helped shape the Moon, originated in the inner Solar System.
For decades, researchers supported the idea that Theia collided with early Earth about 4.5 billion years ago.
That violent impact produced debris that later formed the Moon and spread Theia’s material across both bodies.
Scientists have studied this giant impact theory since Apollo missions first returned lunar samples.
Theia vanished billions of years ago, leaving no direct proof, and its original makeup remained unclear.
Astronomers now use detailed isotope comparisons to reconstruct Theia’s chemical past.
Jake Foster from the Royal Observatory Greenwich said the findings offer rare insight into a destroyed world.
He noted that scientists can still locate Theia’s origin despite its complete disappearance.
Chemical Traces Reveal a Lost World
The research team examined Earth rocks and Apollo lunar samples to analyse their isotopes.
These isotopes act as chemical signatures that reveal ancient planetary histories.
Scientists already knew that Earth and Moon materials share nearly identical metal isotope patterns.
That similarity made it challenging to distinguish early Earth material from debris left by Theia.
Researchers used a reverse-engineering method to overcome this obstacle.
They studied isotopes of iron, chromium, zirconium, and molybdenum to test hundreds of early-Solar-System scenarios.
Their models explored combinations that could produce today’s isotope fingerprints.
Materials near the Sun formed under different temperatures and pressures than those farther away.
These conditions created distinct isotope distributions across various regions of the Solar System.
By comparing these distributions, researchers determined that Theia likely formed closer to the Sun than early Earth.
Some earlier theories suggested Theia may have originated farther out, but new evidence challenges that view.
A Clearer Picture of Planetary Beginnings
The study strengthens the idea that inner-Solar-System materials shaped the Moon’s earliest structure.
The analysis also provides a foundation for future work on planetary formation.
Scientists hope these results will help them understand how young planets grow, collide, and transform.
Researchers believe this approach will guide new investigations of early solar system evolution.
The findings also highlight how ancient rocks preserve clues about vanished worlds.
Astronomers continue to use these clues to reconstruct events from billions of years ago.
