ERIE, Pa. — For nearly 40 years, scientists have generally agreed that Earth’s Moon formed from debris after a Mars-sized object slammed into our young planet. However, new research suggests a different possibility: our Moon may have been captured from space, originally paired with another rocky object before Earth’s gravity pulled it into orbit.
This new theory helps address some puzzling aspects of the Moon’s orbit that are difficult to explain with the traditional collision theory. Moreover, the traditional belief doesn’t account for certain chemical signatures found in Moon rocks brought back by Apollo astronauts.
The study, published in The Planetary Science Journal by Penn State researchers Darren Williams and Michael Zugger, demonstrates that Earth could have acquired its Moon through a process called binary-exchange capture – the same mechanism thought to explain how Neptune captured its largest moon, Triton.
“The Moon is more in line with the sun than it is with the Earth’s equator,” Williams explains in a media release.