Scientists Think They've Found 'Blobs' From Planet that Collided with Earth to Form the Moon

"Slabs of material from an ancient extraterrestrial planet are hidden deep within the Earth," argues a new scientific theory (as described by CNN). "Scientists widely agree that an ancient planet likely smashed into Earth as it was forming billions of years ago, spewing debris that coalesced into the moon that decorates our night sky today." But then whatever happened to that planet? No leftover fragments from a hypothetical planet "Theia" have ever been found in our solar system. But the new theory "suggests that remnants of the ancient planet remain partially intact, buried beneath our feet." If the theory is correct, it would not only provide additional details to fill out the giant-impact hypothesis but also answer a lingering question for geophysicists. They were already aware that there are two massive, distinct blobs that are embedded deep within the Earth. The masses - called large low-velocity provinces, or LLVPs - were first detected in the 1980s. One lies beneath Africa and another below the Pacific Ocean. The study's lead author (Dr. Qian Yuan, a geophysicist and postdoctoral fellow at the California Institute of Technology) first proposed the idea for a paper three times in 2021 - and was rejected each time. But "then he came across scientists who did just the type of research Yuan needed."Their work, which assigned a certain size to Theia and speed of impact in the modeling, suggested that the ancient planet's collision likely did not entirely melt Earth's mantle, allowing the remnants of Theia to cool and form solid structures instead of blending together in Earth's inner stew... If Theia were a certain size and consistency, and struck the Earth at a specific speed, the models showed it could, in fact, leave behind massive hunks of its guts within Earth's mantle and also spawn the debris that would go on to create our moon... The study Yuan published this week includes coauthors from a variety of disciplines across a range of institutions, including Arizona State, Caltech, the Shanghai Astronomical Observatory and NASA's Ames Research Center.

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