Van Allan radiation belts

Geiger counters on some the first artifical satellites discovered two belts of cosmic charged particles interacting with the Earth's magnetic field. These are "magnetic bottles" that extend from 800-4000 km and roughly 3000-10000 km above the surface of the Earth and entrap protons and electrons largely originating from the solar wind (see Figure); though the inner belt may be the result of radioactive decay of secondary cosmic ray neutrons . The leak at the north and south magnetic poles is the cause of the auroral activity .