During the height of the Cold War, the U.S. military and atomic scientists decided to fire some nuclear rockets into space. The goal wasn’t to see how much damage the nuclear explosions could do — by the early 1960s the military had enough nuclear weapons and enough understanding of their explosive potential — but rather to study the side effects of a nuclear explosion. And the result accidentally caused a massive crimson aurora visible hundreds of miles away from the launch site.
The U.S. military had carried out several nuclear tests throughout the 1950s. However an agreed international moratorium on testing put a pause on that for several years. Heading into the 1960s, military officials were hoping to further study some phenomena observed in the past tests. Namely, how a nuclear explosion can cause an electromagnetic pulse that can ionize parts of space and also cause communications blackouts. Although fears of EMPs can be overblown, at the time American military figures did not know enough. Then in 1961 nuclear tests restarted, with the military launching Operation Fishbowl the following year. A series of new tests, all launched from Johnston Atoll in the Pacific Ocean, was initiated by the military’s Defense Atomic Support Agency.
The military had already carried out several nuclear tests in the upper atmosphere. 1958’s Operation Argus saw the U.S. Navy fire three nuclear rockets into the sky, with the hopes of seeding Earth’s magnetic belts enough radiation so that it could create a kind of death cloud that would block transmissions. The tests did partially succeed, but not in the way hoped. But it and other tests before the moratorium had presented the potential for EMPs to be further studied. Beyond further overall weapons testing, the military was looking to see if the EMP effect afterward was minor or could be a tool targeting terrestrial forces — essentially a “Goldeneye” situation.
Starfish Prime, as the third Fishbowl test was called, proved one of the most significant. Like the others, it utilized a Thor rocket with a W49 nuclear warhead. It took off July 9, 1962. The rocket shot through the atmosphere, detonating roughly 250 miles above the surface.
Due to where in the Earth’s magnetic fields the test was done, the radiation burst from the nuclear warhead was far bigger than expected. The 1.4 megaton explosion created “an artificial radiation belt and raising the intensity levels of the natural Van Allen Belt electron population in the inner zone by several orders of magnitude,” one NASA report on the test said.
The result was a vibrant crimson sky, visible several hundred miles away. It was nighttime in Hawaii and residents saw a flash of light in the sky. Shortly after the detonation, a blackout hit, with lights on Honolulu going dark and communications going down. But the sky was lit up, first a bright crimson then a wave of different colors. The effect lasted for several minutes across the Pacific, according to witnesses in Hawaii and elsewhere.
The sudden man-made aurora wasn’t a total surprise to the military and assorted scientists, although the intensity was. A similar phenomenon had occurred during Operation Argus, with witnesses reporting a vast array of colors stemming from one of the three missile tests.
The United States and Soviet Union concluded upper-atmosphere testing in the fall. The Cuban Missile Crisis and the brink of nuclear war in October caused leaders of the two nations to step back from the tests. But Operation Fishbowl had given researchers new insight into the wider electromagnetic impacts of nuclear explosions in the upper atmosphere.
There were other lasting side effects from the Starfish Prime test. Heightened radiation levels ended up knocking out several satellites in the following months, including a telecommunications satellite called Telstar 1, which launched only a day after the Starfish Prime test.
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