Van Allen radiation belt

This CGI video illustrates changes in the shape and intensity of a cross section of the Van Allen belts.
A cross section of Van Allen radiation belts
Part of a series of articles about
Heliophysics
Heliospheric current sheet
Heliospheric current sheet
Fundamentals
Interplanetary medium
Magnetospherics
Solar phenomena

The Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet's magnetosphere. Earth has two such belts, and sometimes others may be temporarily created. The belts are named after James Van Allen, who published an article describing the belts in 1958.[1][2]

Earth's two main belts extend from an altitude of about 640 to 58,000 km (400 to 36,040 mi)[3] above the surface, in which region radiation levels vary. The belts are in the inner region of Earth's magnetic field. They trap energetic electrons and protons. Other nuclei, such as alpha particles, are less prevalent. Most of the particles that form the belts are thought to come from the solar wind while others arrive as cosmic rays.[4] By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.

The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time near that zone. Apollo astronauts going through the Van Allen belts received a very low and harmless dose of radiation.[5][6]

In 2013, the Van Allen Probes detected a transient, third radiation belt, which persisted for four weeks.[7]

  1. ^ J. A. VAN ALLEN; G. H. LUDWIG; E. C. RAY; C. E. McILWAIN (1958). "Observation of High Intensity Radiation by Satellites 1958 Alpha and Gamma" (PDF). Journal of Jet Propulsion. 28:9: 588–592. doi:10.2514/8.7396.
  2. ^ "'Doughnuts' of radiation ring earth in space". Victoria Advocate. (Texas). Associated Press. December 28, 1958. p. 1A.
  3. ^ Zell, Holly (February 12, 2015). "Van Allen Probes Spot an Impenetrable Barrier in Space". NASA/Goddard Space Flight Center. Archived from the original on 2020-03-06. Retrieved 2017-06-04.
  4. ^ "Van Allen Radiation Belts". HowStuffWorks. Silver Spring, Maryland: Discovery Communications, Inc. 2009-04-23. Retrieved 2011-06-05.
  5. ^ Cite error: The named reference popsci.com was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Woods was invoked but never defined (see the help page).
  7. ^ Phillips, Tony, ed. (February 28, 2013). "Van Allen Probes Discover a New Radiation Belt". Science@NASA. NASA. Archived from the original on 2019-12-07. Retrieved 2013-04-05.