Van Allen radiation belts

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Van 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 secured by launching the first U.S. earth satellite, Explorer I, sent up during 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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 of 1957–58. The belts were named for James A. Van AllenVan 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.
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, the American astrophysicist who first predicted the belts and then was first to interpret the findings of the Explorer satellite. In 2012 NASA space probes studying the belt tracked the formation of a third belt, between the two belts previously known. This third belt and the outer belt disappeared several weeks after the third belt appeared; the outer belt subsequently re-formed.

The region of the radiation belts has been given the name of magnetosphere to distinguish it from the atmosphereatmosphere
[Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied, the science of
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. The high-energy particles of which the belts are composed circulate along the earth's magnetic lines of force extending from the area above the equator to near (but not above) the North and South Poles. The inner belt is mainly protons with some electrons; the outer one mainly electrons. The particles of the inner belt are believed to be produced by the collisions of cosmic rayscosmic rays,
charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, oxygen, and
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 with atoms in the upper atmosphere. Those of the outer belt are believed to originate both from the atmosphere and from the solar windsolar wind,
stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds.
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; particles from the solar wind become trapped by the earth's magnetic field and are responsible for 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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 seen at polar regions. A part of a belt dips into the upper region of the atmosphere over the South Atlantic to form the Southern Atlantic Anomaly. This can present a dangerous hazard to satellites orbiting the earth.

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Van Allen radiation belts

(van al -ĕn) Two regions within the Earth's magnetosphere in which charged particles become trapped and oscillate backward and forward between the magnetic poles as they spiral around magnetic field lines. The lower belt, which on average lies 5000 km above the equator, contains protons and electrons either captured from the solar wind or derived from collisions between upper atmosphere atoms and high-energy cosmic rays. The upper belt lies between about 25 000 and 36 000 km or more above the equator but curving downward toward the magnetic poles; it contains fewer and less-energetic particles than the lower belt, mainly electrons from the solar wind. The belts were discovered by James Van Allen in the course of his analysis of observations by early Explorer satellites in 1958.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
References in periodicals archive ?
SAMPEX--the Solar, Anomalous, and Magnetospheric Particle Explorer-- continuously samples the Van Allen radiation belts around Earth.
The two best known effects of the interaction between the solar wind and the magnetosphere are the aurora borealis and the Van Allen radiation belts. These reactions have been studied closely since Van Allen's discovery in 1958.
The findings, says Ryan, support the theory that some protons get trapped in the magnetic arches of the corona, rattling back and forth inside a kind of magnetic slinky Earth's Van Allen radiation belts trap protons in a similar way, he adds.
25 ( ANI ): Scientists have explained the unprecedented behavior of a previously unknown third radiation ring that made a brief appearance between the inner and outer rings of Van Allen radiation belts in September 2012 and persisted for a month.
If you know anything about space exploration, you probably know of the Van Allen radiation belts that encircle Earth.
Andrei Konradi at NASA's Johnson Space Center in Houston notes that the growing amount of space trash may noticeably reduce the number of charged particles in Earth's Van Allen radiation belts.
Shprits, who was honored by President Obama last July with a Presidential Early Career Award for Scientists and Engineers, asserted that the Van Allen radiation belts can no longer be considered as one consistent mass of electrons since they behave according to their energies and react in various ways to the disturbances in space.
The Van Allen radiation belts, discovered by the Explorer 1 satellite in 1958, were the first evidence of our magnetic protection.
At its highest point, or apogee, some 232,000 miles above Earth (58.7 earth radii), it avoids the hazards posed by the Van Allen radiation belts, which extend from about 621 to 37,282 miles above the surface.
The 84-pound space probe collected new data on the Van Allen radiation belts that would help others follow it into cislunar space.
Washington, July 26 ( ANI ): NASA scientists have discovered a massive particle accelerator in the heart of one of the harshest regions of near-Earth space, known as the Van Allen radiation belts.
The belt is composed of particles different from those in Earth's two Van Allen radiation belts, which were discovered in 1958.