This 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
A Van Allen radiation belt is a zone of charged particles which come from the Sun as the solar wind. They are captured and held by the Earth's magnetic field.
Earth has two such belts and sometimes others. The belts were discovered by James Van Allen. Earth's two main belts extend from the altitude of about 500 to 58,000 km (310 to 36,040 mi)
Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.
The belts are in the inner region of Earth's magnetosphere. The belts trap energetic electrons and protons. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend much time in that zone. In 2013, NASA reported that the Van Allen Probes had discovered a third radiation belt, which was observed for four weeks. It was destroyed by a powerful, interplanetary shock wave from the Sun.
Images for kids
Jupiter's variable radiation belts
Cutaway drawing of two radiation belts around Earth: the inner belt (red) dominated by protons and the outer one (blue) by electrons. Image Credit: NASA
Laboratory simulation of the Van Allen belt's influence on the Solar Wind; these aurora-like Birkeland currents were created by the scientist Kristian Birkeland in his terrella, a magnetized anode globe in an evacuated chamber
AP8 MIN omnidirectional proton flux ≥ 100 keV
AP8 MIN omnidirectional proton flux ≥ 1 MeV
AP8 MIN omnidirectional proton flux ≥ 400 MeV