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Analyses of the Earth's magnetic field use a modified version of the usual spherical harmonics that differ by a multiplicative factor. A least-squares fit to the magnetic field measurements gives the Earth's field as the sum of spherical harmonics, each multiplied by the best-fitting Gauss coefficient g m ℓ or h m ℓ. [13]
It was once believed that the dipole, which comprises much of the Earth's magnetic field and is misaligned along the rotation axis by 11.3 degrees, was caused by permanent magnetization of the materials in the earth. This means that dynamo theory was originally used to explain the Sun's magnetic field in its relationship with that of the Earth.
Like the North Magnetic Pole, the North Geomagnetic Pole attracts the north pole of a bar magnet and so is in a physical sense actually a magnetic south pole. It is the center of the 'open' magnetic field lines which connect to the interplanetary magnetic field and provide a direct route for the solar wind to reach the ionosphere.
The field at the surface of the Earth is approximately the same as if a giant bar magnet were positioned at the center of the Earth and tilted at an angle of about 11° off the rotational axis of the Earth (see the figure). [44] The north pole of a magnetic compass needle points roughly north, toward the North Magnetic Pole. However, because a ...
Observed south dipoles during 1903–2000 are yellow squares. IGRF-12 Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellow. [1] The south magnetic pole, also known as the magnetic south pole, is the point on Earth's Southern Hemisphere where the geomagnetic field lines are directed perpendicular to the nominal ...
Earth's magnetic field at 0° latitude (on the equator) 58 μT: 580 mG: Earth's magnetic field at 50° latitude: 10 −4 T 100 μT: 1 G: Magnetic flux density that will induce an electromotive force of 10 −8 volts in each centimeter of a wire moving perpendicularly at 1 centimeter / second by definition (1 gauss = 1 maxwell ...
In three dimensions, the derivative has a special structure allowing the introduction of a cross product: = + = + from which it is easily seen that Gauss's law is the scalar part, the Ampère–Maxwell law is the vector part, Faraday's law is the pseudovector part, and Gauss's law for magnetism is the pseudoscalar part of the equation.
Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that the magnetic field on the surface of Earth resembled that of a terrella, a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory , which attributes Earth's magnetic field to the motion of Earth's iron outer core .