Earth's Inner Core

A solid iron ball as hot as the surface of the Sun/Geology & Minerals

The Earth's inner core is a solid sphere of iron and nickel with a radius of about 1,220 km, sitting at the center of the planet beneath 5,150 km of liquid outer core, mantle, and crust. Despite temperatures reaching 5,400 K (comparable to the Sun's surface), the immense pressure of about 360 gigapascals keeps it solid. The inner core rotates slightly faster than the rest of the Earth and generates the planet's magnetic field through dynamo action in the surrounding liquid outer core.