Theia is thought to have plummeted into an early proto-Earth around 4.5 billion years ago
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Aprotoplanet slammed into Earth about 4.5 billion years ago, knocking loose a chunk of rock that would later become the Moon. Now scientists say remnants can be found lodged deep inside Earth. If remains of the protoplanet, Theia, did stick around after the impact, that may explain why two continent-size blobs of hot rock now lie in Earth’s mantle, one beneath Africa and the other under the Pacific Ocean. These massive blobs would stand about 100 times taller than Mount Everest were they ever hauled up to Earth’s surface.