Moon researchers note that Theia vanished billions ago, leaving no direct chemical proof.
Astronomers in France, Germany, and the United States analysed ancient lunar and terrestrial rocks to identify Theia’s origins.
They propose that a long-lost planet involved in the Moon’s creation formed far nearer to the Sun than many expected.
Scientists now argue that Theia, the world believed to have shaped the Moon, arose from the inner Solar System.
Experts maintain that Theia collided with early Earth about 4.5 billion years ago.
That catastrophic impact hurled debris into space and eventually formed the Moon.
Fragments from Theia settled inside both Earth and the Moon after the collision.
Researchers have debated the giant impact theory since Apollo scientists examined the first lunar samples.
Theia’s disappearance removed direct chemical traces and limited clear evidence for decades.
Its original makeup and true birthplace continued to puzzle planetary scientists.
A multinational team studied ancient rocks from Earth and samples gathered by Apollo missions to resolve the mystery.
Jake Foster of the Royal Observatory Greenwich praised the study’s precision.
He said the findings reveal details about Earth’s infancy with remarkable clarity.
He stressed that scientists investigated a planet that vanished 4.5 billion years ago.
He noted that Theia essentially vaporised, yet researchers still identified its likely birthplace.
Uncovering Hidden Chemical Signatures
The team examined lunar and terrestrial samples to study their isotopes.
These isotopes act like chemical signatures that record planetary histories.
Researchers already knew Earth and Moon samples share nearly identical metal isotope ratios.
That resemblance made Theia difficult to isolate because its debris mixed with early Earth’s material.
Scientists attempted a planetary reconstruction using new isotope comparisons.
By analysing iron, chromium, zirconium, and molybdenum, they modelled hundreds of impact scenarios.
They tested which mixtures of early Earth and Theia could create the isotope patterns found today.
Materials near the Sun formed under unique temperatures and conditions.
Those conditions created distinct isotope structures across different Solar System regions.
By comparing those structures, the team concluded that Theia formed in the inner Solar System.
They believe Theia emerged even closer to the Sun than early Earth.
Previous theories suggested Theia may have formed much farther from the Sun.
Rebuilding the Solar System’s Early Story
Researchers hope this analysis will strengthen studies of early planetary growth.
They aim to improve understanding of how young planets collide and reshape emerging solar systems.
The findings open new paths to explore the origins of terrestrial worlds.
Scientists plan to apply these methods to future samples from other planetary bodies.
They expect deeper insights into how violent impacts influence long-term planetary evolution.
