“New Research Traces Moon-Forming Impact to a Close Inner-Solar-System Protoplanet: Theia”
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A new analysis has shed fresh light on one of the Solar
System’s greatest mysteries — the origin of Theia, the protoplanet
believed to have smashed into early Earth and produced the Moon.
A research team led by Timo Hopp of the Max Planck Institute for Solar
System Research, working with colleagues from the University of Chicago, has
traced Theia’s likely birthplace by examining subtle isotopic signatures
preserved in lunar, terrestrial, and meteoritic samples. Their findings,
published in Science, point toward a surprising conclusion: Theia and
early Earth probably formed side-by-side in the inner Solar System.
Isotopic Evidence: Clues Hidden in Ancient Rock
To track down Theia’s origins, the researchers measured the
ratios of heavy isotopes — including chromium, iron, and zirconium — in Apollo
lunar samples and matching terrestrial rocks.
What they found was striking:
Earth and Moon samples share virtually identical isotopic “fingerprints,”
and these same signatures match meteorites that originated in the non-carbonaceous
inner Solar System.
These isotopic patterns effectively act as a cosmic birth
certificate, marking the region of the solar nebula where a planetary body
formed. The matching values strongly imply that Theia, too, came from the inner
zone of the young Solar System.
Inner Solar System Origins for Earth and Theia
To test this idea, the researchers ran detailed mass-balance
models simulating different Earth–Theia formation scenarios.
The clearest and most consistent solutions were those in which both bodies
accreted from the same inner-disk material, rather than from widely
separated regions.
Lead author Timo Hopp explains that the simplest explanation
is also the most compelling:
Earth and Theia likely grew from neighboring zones of the
inner Solar System before their giant impact.
By comparing Theia’s inferred isotopic profile with known
meteorite groups, the study concludes that Theia probably formed even closer
to the Sun than Earth’s present orbit, reinforcing the idea that the two
worlds were early neighbors destined for a catastrophic collision.
#MoonFormation #Theia #SpaceScience #AstronomyNews
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