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Van Allen radiation belt Definition

Van Al·len radiation belt (van alən)

noun

  1. a broad, doughnut-shaped region surrounding the earth and composed of high-energy electrons and protons trapped in the earth's magnetic field at heights between c. 400 km (c. 250 mi) and c. 64,370 km (c. 40,000 mi)
  2. such a region surrounding other planets, as Jupiter

Etymology: after James A. Van Allen (1914-2006), U.S. physicist