Explainer: Earth — layer by layer - Science News for ...
This solid metal ball has a radius of 1,220 kilometers (758 miles), or about three-quarters that of the moon. It's located some 6,400 to 5,180 kilometers (4,000 to 3,220 miles) beneath Earth's surface. Extremely dense, it's made mostly of iron and nickel. The inner core spins a bit faster than the rest of the planet.
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