Radiation belts are two ring shaped layer of plasmas high above earth’s surface. Earth’s magnetic field is responsible for keeping them in place. Sometimes the inner belt is called Van Allen belt because James Van Allen discovered it in 1958.
The lower belt
The lower belt starts at top of the atmosphere and exists up to 4,000 miles above earth’s surface. High energy protons are the main constituent of the belt. These protons are by product of cosmic radiation. Energy of these protons range from 10MeV to 50MeV.
The outer belt
The outer belt starts from 8,000 miles above and ends at 26,000 miles. Electrons are the main constituent of this belt and this belt is relatively thicker. Proton, Oxygen ion and alpha particles are also available here. There is a safe zone between these two belts.
Magnetic field of the earth interacts with the particles and it can accelerate them nearly to the speed of light.
These belts shield us from harmful charged particles coming from the sun and other sources of the universe. But these belts can be harmful when they are struck by solar storms. Charged particles of these belts may create problem for satellite communication system and power grids on earth. During the solar storm these belts also pose a threat to astronauts.
The earth’s magnetic field lines plunge into North and South Poles. Whirlpool of charged particles is created in the polar regions. Charged particles from radiation belt can crash into the upper atmosphere and bounce back due to whirlpool, these produces aurora in the polar region.
You tube video on Van Allen radiation belts: