The geomagnetically trapped corpuscular radiation

Introduction—One of the most interesting geophysical discoveries of recent years was that made with the early United States satellites Explorer I (satellite 1958α) and Explorer III (satellite 1958γ). It was found Van Allen, 1958; Van Allen and others, 1958 that an immense region around the earth is occupied by a very high intensity of charged particles (protons and electrons), temporarily trapped in the geomagnetic field. The detailed study of this radiation has been a major endeavor of the past year and a half by a group at the State University of Iowa in the United States, and by IGY workers in the Soviet Union. Important additional information at relatively low altitudes has been obtained in rocket experiments flown by other workers.