In 1958 the United States launched its first satellite, Explorer 1, into orbit. Among the scientific instruments aboard Explorer 1 was a radiation detector designed by James Van Allen (1914–2006), a professor of physics at the University of Iowa. It was this detector that first discovered the two belt-shaped regions of the magnetosphere filled with highly charged particles. These regions were subsequently named the Van Allen belts.
The first two Van Allen belts were discovered encircling Earth in 1958, and a third was found by NASA’s Van Allen Probes in 2012. (NASA/Van Allen Probes/Goddard Space Flight Center)