Turning Night Into Day: Nuclear Explosions in Space

On August 1, 1958, a few minutes before midnight, an intense flash of white light tore across the night sky illuminating everything it touched for miles around Johnston Island, a tiny atoll located smack in the middle of the Pacific Ocean. The black sky turned blue, and personnel at the air force base instinctively ducked for cover. The source of the light was a nuclear test conducted high up in the atmosphere. It was one of two conducted under Operation Hardtack to study, among other things, the effect of the earth’s rarefied atmosphere on nuclear detonation, as well as to investigate defensive tactics against ballistic missiles. This particular test, codenamed “Teak”, was the most powerful one at 3.8 megaton—equivalent to 250 Hiroshima-grade nuclear bombs. The fireball from Operation Hardtack “Teak”. The high altitude of the detonation (76 kilometers) enabled the flash of light to be seen from far away. In Hawaii, 1,500 km away, a thousand startled residents called the police to report strange lights on the sky. The sky had turned from dark to yellow to orange and then red. “The red spread in a semi-circular manner until it seemed to engulf a large part of the horizon. A cloud rose in the center of the circle. It was quite large and clearly visible. It remained visible for about a half-hour,” a witness in Honolulu described. Military and civilian air traffic communications were knocked out for several hours, and many trans-Pacific high-frequency communication networks that utilized the ionosphere for transmission were disrupted for up to nine hours. In distant Western Samoa, 3,200 kilometers to the south, the explosion produced a brilliant display of aurora. Astronomers at Apia Observatory measured the strength of the electromagnetic pulse (EMP) and found it to be four times stronger than any created by solar storms.   Four years later, the United States conducted another series of high-altitude nuclear tests.