Researchers are fairly certain that we gained our favorite satellite, the moon, after a planet, Theia, collided with the proto-Earth 4.5 billion years ago. What’s not certain are the details surrounding Theia’s fate. Was it a hit-and-run, or did the mantles of the two planets merge?
Qian Yuan, Earth scientist at Arizona State University, and his colleagues recently suggested a new line of evidence to support the latter hypothesis, suggesting that Theia not only merged with Earth, but we might know right where the remnants of its mantle reside in Earth.
