1. Two zones of charged particles around the earth's magnetosphere, discovered in 1958 by U.S. physicist Jame Van Allen.

The atomic particles came from the earth's upper atmosphere and the solar wind, and are trapped by the earth's magnetic field.

The inner belt lies above the equator, and contains protons and electrons from the solar wind.

2. One of two regions, lying at about 1,900 miles, 3,000 kilometers, and 12,500 miles, 20,000 kilometers, above the equator, in which charged particles, trapped in the earth's magnetosphere, oscillate between the magnetic poles.

The particles are caught from the solar wind or produced by collisions between air molecules and cosmic rays.