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Earth's outer core is a fluid layer about 2,260 km (1,400 mi) in height (i.e. distance from the highest point to the lowest point at the edge of the inner core) [36% of the Earth's radius, 15.6% of the volume] and composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. [31]
Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 20% of Earth's radius or 70% of the Moon's radius. [1] [2] There are no samples of the core accessible for direct measurement, as there are for Earth's mantle. [3]
Earth is orbited by one permanent natural satellite, the Moon, which orbits Earth at 384,400 km (1.28 light seconds) and is roughly a quarter as wide as Earth. The Moon's gravity helps stabilize Earth's axis, causes tides and gradually slows Earth's rotation. Tidal locking has made the Moon always face Earth with the same side.
Gravity at different internal layers of Earth (1 = continental crust, 2 = oceanic crust, 3 = upper mantle, 4 = lower mantle, 5+6 = core, A = crust-mantle boundary) Earth's radial density distribution according to the Preliminary Reference Earth Model (PREM). [13] Earth's gravity according to the Preliminary Reference Earth Model (PREM). [13]
For example, the Earth's mean specific gravity (5.515) is far higher than the typical specific gravity of rocks at the surface (2.7–3.3), implying that the deeper material is denser. This is also implied by its low moment of inertia ( 0.33 M R 2 , compared to 0.4 M R 2 for a sphere of constant density).
The rotation axis of Earth is centered and vertical. The dense clusters of lines are within Earth's core. Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun.
The internal structure of the inner planets. The internal structure of the outer planets. A planetary core consists of the innermost layers of a planet. [1] Cores may be entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. [2]
The global definition of the Earth's field is based on a mathematical model. If a line is drawn through the center of the Earth, parallel to the moment of the best-fitting magnetic dipole, the two positions where it intersects the Earth's surface are called the North and South geomagnetic poles.