magnetosphere

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magnetosphere The space around a planet in which ionized particles are affected by the planet's magnetic field. The Earth's magnetosphere reaches far beyond the atmosphere. In the magnetosphere, charged particles are concentrated at altitudes of about 3000 km and 1600 km. The charged particles oscillate between the northern and southern hemispheres. The outer boundary of the magnetosphere is sharp and well defined, extending to about 10 Earth radii on the sunlit side of the Earth and to perhaps 40 Earth radii on the dark side; but the boundary changes its position in response to solar activity, being depressed by the solar wind. See also exosphere and ionosphere.

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