Earth’s core is a billion years old – Space.com

The solid inner core of Earth is a mere billion years old, new research finds.
Modern Earth
is like a layer cake, with a solid outer crust, a hot, viscous mantle, a liquid outer core and a solid inner core. That solid inner core is growing slowly as the liquid iron
in the core cools and crystallizes. This process helps power the churning motion of the liquid outer core, which in turn creates the magnetic field that surrounds Earth and helps protect the planet from harmful cosmic radiation.
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