Glossary / Space
Van Allen belt
Doughnut-shaped regions where high-energy protons and electrons are trapped by Earth's magnetic field. There is an inner and an outer belt.
In 1958 the radiation counters on Explorer 1 and 3, America's first satellites, saturated above a certain altitude. James Van Allen and colleagues at the University of Iowa concluded that the instruments were not broken but had entered a band of intense radiation[1] — the first major scientific discovery of the space age.
Because the belts damage satellite electronics and raise astronaut radiation doses, orbit design considers how to avoid them or cross them quickly.
Related terms
- Geostationary orbitA circular orbit about 36,000 km above the equator. It matches Earth's rotation, so a satellite there appears fixed in the sky.
- HeliopauseThe boundary where the flow of particles from the Sun (the solar wind) is stopped by the gas between the stars — one definition of the outer edge of the solar system.