50 years ago today the U.S. detonated a nuclear weapon 250 miles up in space. This was the Starfish Prime test.The warhead launched by a Thor missile reached an altitude of  680 miles and was detonated on its downward flight.

A total of 27 small rockets were launched to obtain data on the explosion.

rocket set to take readings from Starfish Prime explosion

…and what an explosion it was. The resulting EMP knocked out the lights in Hawaii over 1000 miles away.

Here is a great documentary video that includes Van Allen’s role in the Starfish Prime test


Here is the official U.S. declassified film about it