Van Allen, James Alfred

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Van Allen, James Alfred,

1914–2006, American physicist and space scientist, Mt. Pleasant, Iowa. A graduate (Ph.D 1939) of and professor of physics (1951–85) at what is now the Univ. of Iowa, where he was an influential teacher, Van Allen discovered what are now known as the Van Allen radiation beltsVan Allen radiation belts,
belts of radiation outside the earth's atmosphere, extending from c.400 to c.40,000 mi (c.650–c.65,000 km) above the earth. The existence of two belts, sometimes considered as a single belt of varying intensity, was confirmed from information
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, regions of intense radiation surrounding the earth in space. The belts were first identified by instruments Van Allen prepared that were launched in U.S. Explorer and Pioneer satellites (1958).

During his long, productive career, Van Allen helped develop (1940–42) a proximity fuse for antiaircraft ammunition and subsequently served as a naval gunnery officer in World War II. After the war, he conducted high-altitude research using rockets and balloons, and discovered (1953) the electrons associated with the aurora borealisaurora borealis
and aurora australis
, luminous display of various forms and colors seen in the night sky. The aurora borealis of the Northern Hemisphere is often called the northern lights, and the aurora australis of the Southern Hemisphere is known as the southern
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. Van Allen also was prominent among the scientists who proposed (1950) and organized the international scientific research program that became the International Geophysical YearInternational Geophysical Year
(IGY), 18-month period from July, 1957, through Dec., 1958, during a period of maximum sunspot activity, designated for cooperative study of the solar-terrestrial environment by the scientists of 67 nations.
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Although he supported the development of the U.S. space exploration efforts that culminated in the Apollo space program and moon landings (1969–72), the relative paucity of scientific data reaped by human spaceflight led him to champion the use of space probes and satellites. He subsequently studied the radiation belts of Jupiter and Saturn using data from Pioneer probes and participated in the Galileo mission to Jupiter.