‘Forget everything you knew’: Scientists reveal the Moon may have been ‘captured, not created’
Produced by: Manoj Kumar
Lunar Mystery
For centuries, scientists have puzzled over the moon’s origins, hypothesizing it was born from a colossal cosmic event, yet no theory fully satisfied every detail.
Impact Theory
The dominant idea since the 1980s was a massive impact with a protoplanet named Theia, which purportedly collided with Earth, ejecting debris that coalesced to form the moon.
Collision Caveat
While plausible, the impact theory struggles to explain certain features—like the moon’s inclined orbit and slight chemical discrepancies with Earth’s material.
Binary Theory Twist
Enter researchers from Penn State University proposing an alternative: Earth may have captured the moon from a passing binary system—a cosmic duo locked in orbit.
Gravitational Snatch
In this scenario, Earth’s gravity “snatched” one body from the binary pair, trapping it in orbit, while the other was flung off, providing a unique formation route.
Tilted Orbit Explained
This binary-exchange capture could explain the moon’s tilted orbit, diverging seven degrees from Earth’s equatorial plane—a detail unexplained by impact theories.
The Triton Parallel
Lead researcher Professor Darren Williams points to Triton, Neptune’s moon, captured from a binary. Triton’s similarly inclined orbit hints Earth’s moon may share this origin.
Calculated Capture
Published in The Planetary Science Journal, the study calculates Earth could capture a body of up to 10% of its mass if it passed within 80,000 miles at 6,700 mph.
Tidal Shaping
Initially, the moon’s orbit would have been elliptical, like a comet’s, but Earth’s tides gradually tamed it, bringing it to its present near-circular path.
New Doors Open
Professor Williams adds, “This theory opens a treasure trove of questions, suggesting binary systems may have played a far greater role in planetary evolution.”