Van Allen Belts

The Van Allen Radiation Belt is a torus of energetic charged particles (plasma) around Earth, held in place by Earth's magnetic field. The Van Allen belts are closely related to the polar aurora where particles strike the upper atmosphere and fluoresce.The presence of a radiation belt had been proposed by Nicholas Christofilos  prior to the Space Age and was confirmed by the Explorer I on January 31, 1958, and Explorer III missions, under Dr. James Van Allen at the University of Iowa. The trapped radiation was first mapped out by Sputnik 3,  Explorer IV, Pioneer III and Luna 1.
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