ANALYSIS: Space Radiation Probes Make ‘Shock' Discovery
The belts were discovered by Explorer 1, the first American satellite that went into space in 1958. They are named after James Van Allen, the space scientist who designed a cosmic ray instrument on that satellite. (He detected fewer cosmic rays than expected and suggested it may be due to radiation belts, which were confirmed in a later mission.) The belts' shape changes depending on many factors, such as if the sun has recently sent a solar flare that hit the Earth's magnetic environment.
Initially, scientists built up a very simple picture of the belts: a small inner belt, an empty space (called the "slot region"), and an outer belt that has a lot of electrons and is highly changeable.
NEWS: Probes Launched Into Earth's Radiation Zone
The new research shows that these belts change frequently. If there's a big solar storm, for example, the region merges into one large belt. Sometimes you'll see a large inner belt and a small outer belt. Sometimes there will be an outer belt, but no inner belt at all.