New Theoretical Models Salvage Moon-Forming Impact Theory

Theia impacting proto-Earth, image by Fahad Sulheria.

One of the widest accepted models for the Moon’s formation states that a renegade, Mars-sized planet, named Theia, slammed into Earth 4.5 billion years ago, and pushed up debris that would eventually coalesce into a satellite. This theory has been able to predict and explain many facts, like the mass of Earth and the Moon, but it also says that most of the lunar-forming debris stemmed from Theia, not proto-Earth. Theia is thought to have originated from a different part of the Solar System, with different elemental isotopes, which conflicts with some of the more sensitive measurements of the past decade showing that rocks from Earth and the Moon have identical isotopic ratios of oxygen, titanium, chromium, and tungsten.

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