Earth's core

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Structure of Earth

The Earth's core is the part of Earth in the middle of our planet. It has a solid inner core and a liquid outer core.

Outer core[change | edit source]

The outer core of the Earth is a liquid layer about 2,266 kilometers thick. It is made of iron and nickel. This is above the Earth's solid inner core and below the mantle. Its outer boundary is 2,890 km (1,800 mi) beneath the Earth's surface. The transition between the inner core and outer core is approximately 5,150 km beneath the Earth's surface.

The temperature of the outer core ranges from 4400 °C in the outer regions to 6100 °C near the inner core. Eddy currents in the nickel iron fluid of the outer core are believed to influence the Earth's magnetic field.

The average magnetic field strength in the Earth's outer core was measured to be 25 Gauss, 50 times stronger than the magnetic field at the surface.[1][2]

The outer core is not under enough pressure to be solid, so it is liquid even though it's mostly made of the same stuff as the inner core. Sulfur and oxygen could also be in the outer core.

Without the outer core, life on Earth would be very different. Convection of liquid metals in the outer core creates the Earth's magnetic field.[3][4] This magnetic field extends outward from the Earth for several thousand kilometers, and creates a protective bubble around the Earth that deflects the Sun's solar wind. Without this field, the solar wind would directly strike the Earth's atmosphere. This might have removed the Earth's atmosphere, making the planet nearly lifeless. It may have happened to Mars.[5]

Inner core[change | edit source]

The inner core of the Earth, as detected by seismology, is a solid sphere about 1,216 km (760 mi) in radius, or about 70% that of the Moon.

It is believed to be an ironnickel alloy, and may have a temperature similar to the Sun's surface, approximately 5778 K (5505 °C).[6]

References[change | edit source]