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A rendering of the magnetic field lines of the magnetosphere of the Earth.. In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field.
Schematic of the Birkeland or Field-Aligned Currents and the ionospheric current systems they connect to, Pedersen and Hall currents. [1]A Birkeland current (also known as field-aligned current, FAC) is a set of electrical currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high latitude ionosphere.
Earth's ring current is responsible for shielding the lower latitudes of the Earth from magnetospheric electric fields. It therefore has a large effect on the electrodynamics of geomagnetic storms . The ring current system consists of a band, at a distance of 3 to 8 R E , [ 1 ] which lies in the equatorial plane and circulates clockwise around ...
Magnetic reconnection is a breakdown of "ideal-magnetohydrodynamics" and so of "Alfvén's theorem" (also called the "frozen-in flux theorem") which applies to large-scale regions of a highly-conducting magnetoplasma, for which the Magnetic Reynolds Number is very large: this makes the convective term in the induction equation dominate in such regions.
(This simple definition assumes a noon-midnight plane of symmetry, but closed fields lacking such symmetry also must have cusps, by the fixed point theorem.) The amount of solar wind energy and plasma entering the actual magnetosphere depends on how far it departs from such a "closed" configuration, i.e. the extent to which Interplanetary ...
Artistic representation of Earth's magnetosphere. The plasma sheet is highlighted in yellow. In the magnetosphere, the plasma sheet is a sheet-like region of denser (0.3-0.5 ions/cm 3 versus 0.01-0.02 in the lobes) [citation needed] hot plasma and lower magnetic field located on the magnetotail and near the equatorial plane, between the magnetosphere's north and south lobes.
The phase velocity of an electromagnetic wave in such a medium is = = + For the case of an Alfvén wave = + where is the Alfvén wave group velocity. (The formula for the phase velocity assumes that the plasma particles are moving at non-relativistic speeds, the mass-weighted particle velocity is zero in the frame of reference, and the wave is ...
This dispersion relation has three independent roots: one corresponding to the Alfvén wave and the other two corresponding to the magnetosonic modes. From the eigenvalue equation, the y-component of the velocity perturbation decouples from the other two components giving the dispersion relation ω 2 A = v 2 A k 2 ∥ for the Alfvén wave. The ...