The Van Allen radiation belts are a pair of doughnut shaped rings composed of plasma (ionized gas). This phenomenon is caused by the interaction between the Earth's magnetic field and the Sun's solar wind. First discovered by the American satellite Explorer 1, the Van Allen radiation belts are areas of intense radiation that is formed by the rapidly moving harged particles trapped by Earth's magnetic field. The outer belt measures to be 19,000 kilometers in altitude to 41,000 kilometers. The inner belt is somewhere between 13,000 kilometers and 7,600 kilometers high.
Van Allen Radiation Belts 
