An Etymological Dictionary of Astronomy and Astrophysics

The ring-shaped regions of charged particles surrounding the Earth from 1 to 6 Earth radii into space. The charged particles are trapped in by the Earth’s magnetic field. The inner belt is between 1.2 and 4.5 Earth radii and contains high-energy electrons and protons which originate mainly from interactions between cosmic rays and the upper atmosphere. The outer belt, located between 4.5 and 6.0 Earth radii, contains lower-energy charged particles mainly coming from the solar wind.

See also: Named after James Van Allen (1914-2006), who discovered the belts
in 1958 based on measurements made by Explorer 1, the USA’s first successful artificial satellite; → belt.