The idea that the Moon was once part of Earth was suggested as far back as 1898, but it wasn’t until the mid-70s that the giant impact hypothesis — which suggests that the Moon was formed via the massive collision between Earth and another Mars-sized body — first gained favor. In 2001, Canup and Asphaug published solid calculations in support of the hypothesis, but physical proof of the impact has yet to be found. But according to new research, that may have changed.
A paper published today in Nature by Frédéric Moynier and Randal Paniello of Washington University in St. Louis, and James Day of Scripps, shares findings of a chemical analysis of Moon rocks that shows a fractional difference in their makeup as compared to samples from the Earth. Although the two are markedly similar, it’s been previously shown that Moon rocks lack volatile elements, which suggests they may have evaporated during the incredibly intense heat and pressure created during an impact event. But if the hypothesis that light elements actually evaporated from Moon rocks during their formation is correct, you’d expect to find evidence of elements being layered by mass — heavier elements would condense first, and so on.
