What are the Van Allen radiation bells?

 

What are the Van Allen radiation bells?

No one knew the Van Allen radiation belts existed until the first American satellite, Explorer I, discovered the intense inner radiation zone in early 1958 with the use of onboard Geiger counters. The space probe Pioneer 3 also detected the outer radiation belt in late 1958. Although it did fail in its mission to reach the Moon, its objectives were changed to measure the Van Allen outer radiation belt during its 38 hour and 6 minute flight.

Named after James Van Allen of the University of Iowa, who first interpreted the data, the two doughnut-shaped rings of ionized gas (plasma) circle the Earth's equator. They form as rapidly moving charged particles from the solar wind become trapped by the Earth's magnetic field. The outer belt stretches from 11,806 miles (19,000 kilometers) to 25,476 miles (41,000 kilometers) in altitude; the inner belt lies between 4,722 miles (7,600 kilometers) and 8,078 miles (13,000 kilometers) in altitude. Similar radiation belts have been found around other planets in our solar system.

The inner and outer belts are not the only radiation zones encircling the Earth, however. In 1990, the Combined Release and Radiation Effects Satellite (CRRES) discovered a third radiation belt between the inner and outer Van Allen belts. In addition, scientists determined that other radiation belts can periodically form between the inner and outer belts. For example, around May 8,1998, a series of large solar disturbances caused such a new radiation belt to form, but it eventual disappeared as the solar activity subsided.