Key Takeaways on the Van Allen Belts:
In 1958, James Van Allen discovered far fewer cosmic rays than expected using a cosmic-ray detector and suggested that a belt of strong radiation may have damaged the device. The belts were therefore named in honor of Van Allen.
Van Allen belts are a big, energetic stew of charged particles that encircle Earth. The particles of the outer belt come from the sun by means of solar wind and are trapped by Earth’s magnetic field, or magnetosphere. The particles in the inner belt originate when cosmic rays interact with Earth’s atmosphere.
This intense radiation makes space travel tricky. Astronauts must pass through the Van Allen belts to get to outer space. To do this safely, they must plot their route so they will pass through the weakest part of the belts and spend as little time as possible in this region.
Explorer 1, the first U.S. satellite (launched in 1958, three months after the U.S.S.R. launched Sputnik), found a big surprise in space: the Van Allen belts, rings of radiation that to this day are still being studied and are still complicating space travel.
The satellite carried a cosmic-ray detector designed by physicist James Van Allen of the University of Iowa. The team included the detector because they expected to encounter cosmic rays, which they had recently discovered through balloon measurements.
