NEW YORK – Some 4.5 billion years or so ago, scientists believe, something big smacked into Earth and knocked it ass over teakettle.
The result was a bunch of debris, hurled into space, swirling around until it formed the Moon. Of the big object, thought to be the size of Mars, and named Theia, nothing much was left. Or so we thought.
Researchers from China, the US, and the UK have uncovered evidence that chunks of Theia ended up inside the Moon. And evidence also now suggests that chunks of Theia ended up inside Earth, too.
If that’s the case, the giant impact hypothesis could solve a mystery that has bothered scientists for more than a decade: the presence of dense, continent-sized blobs of material, buried deep under Earth’s mantle some 2,900 kilometers (1,800 miles) down, curved around its core.
“Our findings challenge the traditional notion that the giant impact led to the homogenization of the early Earth,” says Hongping Deng of the Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences.
“Instead, the Moon-forming giant impact appears to be the origin of the early mantle’s heterogeneity and marks the starting point for the Earth’s geological evolution over the course of 4.5 billion years.”
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