The passing of a pioneer

Yesterday I neglected (inexcusably) to note the passing of Dr. James Van Allen, retired professor of physics at the University of Iowa, whose experiment on America's first satellite, Explorer I, led to the discovery of the Van Allen Radiation Belts which circle Earth. He also played a leading role in the early Pioneer program, which sent probes to the edge of the solar system. Dr. Van Allen was 91.

He twice appeared on the cover of Time Magazine, and was universally acknowledged as one of the greatest astrophysicists of our age. But the accomplishment of which he was proudest was having taught basic astronomy to thousands of University of Iowa undergraduates.