Weird chemistry is making the Earth's interior cool faster than thought

Long ago — 4.5 billion years ago, right after the Earth formed — our planet was hot. It formed by essentially getting slammed billions of times by asteroids, and all that energy of impact was enough to keep the Earth broiling.

Eventually heavy elements like iron and nickel sank to the core, and lighter ones rose to the surface. This differentiation created the Earth we see today: An inner, solid nickel/iron core that's nearly as hot as the surface of the Sun; an outer, liquid iron core; the sol...