The Core

Beneath the mantle is the core, a large sphere of metal that occupies Earth's center. Scientists think that the core is composed mostly of iron, with lesser amounts of nickel and some lighter elements. Within the core, pressure increases greatly with depth. At Earth's center, the pressure is estimated to be 3.6 million times the pressure at Earth's surface! The temperature at the center of Earth is estimated to be about 5500°C, nearly equal to the temperature of the sun's surface.

The core is divided into two parts—the outer core and the inner core. In the outer core, high temperatures keep the metal liquid. Because of Earth's rotation, the flowing iron of the outer core produces an electric current and creates Earth's magnetic field. In the inner core, very high pressure is a more important factor than temperature. As a result, the inner core is solid.