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When Did the Earth's Core Separate from its Shell? - Universe Today
Geologists have come up with two measurements of radioactive decay to calculate when the Earth's core separated from its crust, but the problem is, these two numbers don't match. Researchers from the University of Bristol think that the giant collision that occurred early on in Earth's history - which went on to form the Moon - might have reset one of these "countdown clocks" and created the discrepancy.