Van Allen belts

They were detected in 1958 by the American probe Explorer 1, then explored by Explorer and Pioneer. They are arranged parallel to the magnetic equator and are inclined by about 11° to the geographic equator.

The inner belt (at 3500 km): composed mainly of protons, due to the action of cosmic rays that bombard the Earth continuously and, at very low density, and electrons some of which doubtless have the same origin as the protons (except those very abundant ones of less than 1 100 000 volts).

Outer belt (at 20 000 km): composed of electrons.

Without protection, a cosmonaut exposed to radiation from the Van Allen belts would receive several million rads per hour (500 rads are usually fatal).