The Earth's Distant Magnetic Field

Low energy corpuscular radiation from the Sun interacts with the geomagnetic field and produces the magnetosphere. The magnetosphere is a region about the Earth in which the geomagnetic field is confined. When the corpuscular radiation is subsonic the magnetosphere is approximately spherical in shape. In the case of hypersonic corpuscular radiation the magnetosphere is highly asymmetrical and has the shape of a tear-drop with the tail-end pointing away from the Sun. The quantitative treatment is approximate and for hypersonic flow the Newtonian fluid theory is used. If ρU2 is the momentum flux of a hypersonic corpuscular radiation, it is shown that the day-side of the magnetospheric surface is at a distance proportional to (ρU2)−1/6 and the tail-end is at a distance proportional to (ρU2)½. The little that is known about the gegenschein is consistent with the idea that it is located within the magnetosphere, either in the extreme tail-end or in the “magnetic-arch”. Within the framework of an asymmetric magnetosphere there are acceleration mechanisms for accelerating protons to an energy of 100 keV and electrons to an energy of the order of 100 eV. The outstanding feature of these mechanisms is that the energetic particles are only available on the night-side of the Earth in the auroral zones. It is argued that the gegenschein and the auroral displays on the night-side of the Earth are evidence of an asymmetric magnetosphere.