Van Allen Belts - What are they?

The Van Allen belts are regions of charged particles that have become trapped in the Earth's Magnetic field and surround us in two distinct regions or "belts". They are named after James Van Allen who led the team of Physicists that discovered them.

A model of the Van Allen Belts
 

The Inner belt

The inner belt is a confined region of high-energy protons made when high energy cosmic rays from distance galaxies collide with our atmosphere. They are found between 600km and 1000km above the Earth. Prolonged exposure, say during a space flight, would be very hazardous to humans and equipment. This is why low orbit satellites follow paths between the poles of the Earth to minimize time spent in this region.

The outer belt

This is a much more diffuse (thinner) but larger region of particles that have become trapped from the Sun's solar wind.