Renowned physicist and space pioneer James Van Allen who discovered the radiation belts surrounding the Earth has died at the age of 91.

The University of Iowa, where Van Allen taught for years, announced his death Wednesday. The cause of his death was not given.

The highlight of Van Allen's career was in the 1950s when instruments he designed and placed aboard the first U.S. satellite, Explorer One, discovered the bands of radiation surrounding the Earth. Those radiation belts were later named after Van Allen.

Van Allen retired from teaching in 1985, but he continued to monitor data gathered by other satellites and served as an interdisciplinary scientist for the Galileo spacecraft.

Some information for this report was provided by AP.