The Van Allen Belts are a pair of rings, circling the earth, made up of charged particles. Named for astronomer James Van Allen, these cosmic doughnuts were discovered early in the space age - back in the late 1950's, when Van Allen and his team identified two distinct zones of radiation.
This video illustrates changes in the Van Allen belts shape and intensity:
The belts have been the focus of ongoing study ever since, and recently scientists were stunned to find a third belt. Then, within a month of its detection, it disappeared. We’ll speak with science writer Veronique Greenwood.