Nov. 26, 2014 NASA's Van Allen Probes Spot an Impenetrable Barrier in Space
Two donuts of seething radiation that surround Earth, called the Van Allen radiation belts, have been found to contain a nearly impenetrable barrier that prevents the fastest, most energetic electrons from reaching Earth.
This animated gif shows how particles move through Earth’s radiation belts. The sphere in the middle shows a cloud of colder material called the plasmasphere. New research shows that the plasmasphere helps keep fast electrons from the radiation belts away from Earth.