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A magnetic field is a vector field, but if it is expressed in Cartesian components X, Y, Z, each component is the derivative of the same scalar function called the magnetic potential. Analyses of the Earth's magnetic field use a modified version of the usual spherical harmonics that differ by a multiplicative factor.
[12] [13] Mercury, despite its small size, has a magnetic field, because it has a conductive liquid core created by its iron composition and friction resulting from its highly elliptical orbit. [14] It is theorized that the Moon once had a magnetic field, based on evidence from magnetized lunar rocks, due to its short-lived closer distance to ...
IAGA has a long history and can trace its origins to the Commission for Terrestrial Magnetism and Atmospheric Electricity, part of the World Meteorological Organization originated from the International Meteorological Organization (IMO), which was founded in 1873. At the First IUGG General Assembly (Rome, 1922), the Section de Magnétisme et ...
However, modern geophysics organizations and pure scientists use a broader definition that includes the water cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial physics; and analogous problems associated with the Moon and other planets.
A time-varying magnetic field external to the Earth induces telluric currents—electric currents in the conducting ground. These currents create a secondary (internal) magnetic field. As a consequence of Faraday's law of induction, an electric field at the surface of the Earth is induced associated with time variations of the magnetic field ...
The journal was originally founded under the name Terrestrial Magnetism by the American Geophysical Union's president Louis Agricola Bauer in 1896. [2] [3] It was renamed to Terrestrial Magnetism and Atmospheric Electricity in 1899 and in 1948 it acquired its current name. [4]
The strongest are primarily geomagnetically induced currents, which are induced by changes in the outer part of the Earth's magnetic field, which are usually caused by interactions between the solar wind and the magnetosphere or solar radiation effects on the ionosphere. Telluric currents flow in the surface layers of the Earth.
This process creates convection currents in the outer core, which are thought to be the prime driver for the currents that create the Earth's magnetic field. [5] The existence of the inner core also affects the dynamic motions of liquid in the outer core, and thus may help fix the magnetic field. [citation needed]