Is an intact piece of protoplanet Theia locked away inside the Moon? Scott Sutherland mercredi, 11 mars 2020 à 11:30 - New research may solve a persistent mystery about how Earth's Moon formed. New clues to the origin of the Moon surfaced this week, which reveal that the Earth and Moon are not as similar as previously thought, and part of the protoplanet that helped create the Moon may still be preserved deep under the lunar surface. The current theory of how Earth and Moon came to be, as we know them today, is called the Giant-Impact Hypothesis. Essentially, billions of years ago, proto-Earth was all alone as it circled the Sun, until a fateful collision with a Mars-sized protoplanet scientists named Theia. The cataclysmic impact blasted both planets apart, and while much of Theia mixed together with proto-Earth, a cloud of debris that was blasted out into space eventually coalesced and cooled to form the Moon.