Van Allen Belts

Radiation belts of high-energy particles trapped in the earth's magnetosphere. They are doughnut-shaped regions containing mainly protons and electrons. They were discovered by the American scientist James Van Allen in 1958 when cosmic ray detectors on board the first US satellite Explorer I registered signals too high to record when they entered the belts at a height of 2,000 km. The belts extend to a height of 20,000 km or more. The particles originate both from the solar wind and from cosmic rays.

The leak at the north and south magnetic poles is the cause of the auroral activity.

See also: Earth, Radiation Belt.