A Thor rocket detonates 250 miles up; streetlights go dark in Hawaii, and the sky turns red over the Pacific

By the summer of 1962, the United States and Soviet Union were racing to understand what a nuclear bomb would do far above the atmosphere, where no one had reliably tested one. On July 9, a Thor rocket lifted off from Johnston Atoll and detonated a 1.4-megaton warhead 250 miles over the Pacific, 13 minutes and 41 seconds after launch. The blast knocked out streetlights and phone service in Hawaii, 900 miles away, and painted the night sky from Samoa to New Zealand in bands of red and green light. Hotel guests in Honolulu watched from rooftop parties, unaware they were witnessing a radiation belt that would cripple several satellites in the months that followed…