The Cold War brought a number of terrifying things to the forefront of geopolitics, and an entire generation grew up under the constant threat of nuclear annihilation - and with the frequent happenstance of scientific testing meant to further improve humanity’s capability to destroy itself. As the arms race merged with the space race, this eventually included nuclear testing in space, and Starfish Prime was the biggest cosmic nuking ever carried out by the beings of this planet.
The Soviet Union had called for a moratorium on detonation experiments in 1958, and the United States reluctantly played along - until, that is, the Soviets began high-altitude nuclear testing again in 1961, allowing the Americans to respond in kind. It became perfectly clear that nuclear weapons were going to be fired into space on a fairly regular basis for the foreseeable future, and therefore it behooved military scientists to find out what the results and after-effects might be.
Starfish Prime, part of a larger endeavor known as Project Fishbowl, occurred on July 9, 1962, and was an attempt at both understanding and perhaps harnessing the power of nuclear detonations in the upper limits of the atmosphere. While the test was largely considered a failure, it did at the very least fail in a truly spectacular and horrifying way.
Project Fishbowl was an attempt to better understand the effects of a nuclear explosion in space, in anticipation of one or more sides of the Cold War striking their enemies through such methods. The tests also had some more specific goals to manipulate the recently discovered Van Allen radiation belts, a field of magnetically trapped high-energy protons surrounding Earth.
The belts were identified in 1958 by scientist James A. Van Allen, and he immediately agreed with the US government to either destroy or disrupt the field simply because they suspected Russia was going to do the same. Science historian James Fleming suspects that some US scientists also theorized the belts could be weaponized; if enough energy is released into the field, maybe the Van Allen belt could transport and channel it towards a specific target on the ground.
Though Starfish Prime wasn’t the only spacefaring nuclear explosion, it was certainly the largest. The thermonuclear warhead attached to a Thor rocket carried a yield of 1.45 megatons, an incendiary device potential equivalent to 1,450,000 tons of TNT and about 100 times as powerful as the one dropped on Hiroshima at the tail end of World War II.
While the US government typically likes to keep their advanced military testing as classified as possible, it’s rather difficult to hide a nuclear explosion in space from the rest of the world. So rather than hide the experiment, the US government publicized the Starfish Prime test ahead of time. Countless newspaper headlines offered up a dazzling light show to anyone willing to stay up and watch the skies; people were generally excited to see it. Other headlines and several demonstrations, however, protested nuclear testing in space.
Starfish Prime was designated to launch at Johnston Atoll due to its remote location approximately 940 miles southwest of Hawaii in the middle of the Pacific Ocean. Many believed this would prevent the experiment from having any ill effects on any heavily populated areas. In anticipation for the show, some hotels in Honolulu offered “Rainbow Bomb Parties” on their rooftops.
The test began at around 11 pm HST. The Thor projectile took the warhead up to a height of about 660 miles, and then dropped it back down to 240 miles before detonating within Earth’s thermosphere. The warhead erupted high above the Pacific and generated a flash that lit up the night across most of the Pacific. The aftermath included a brilliant red aurora that resembled a sunset in the middle of the night, which lasted for several minutes and could be seen from Tonga to Samoa.
Scientists understood that a nuclear detonation could result in an electromagnetic pulse, or EMP, and that such an occurrence could disrupt electronics, but until Starfish Prime, they had no idea just how widespread and devastating those effects would be. The EMP generated by Starfish Prime was so powerful that it reached several Hawaiian islands, even though they were located hundreds of miles away from the launch site.
Hundreds of streetlights on Hawaii were blown out at once, followed by telephone outages and radio blackouts. At higher altitudes, a few aircraft flying over the Pacific experienced electrical surges, though thankfully there were no collisions.
The island of Kauai was hit hardest by the EMP burst from the Starfish Prime detonation, and the island was effectively cut off from the rest of the world. The people of Kauai were unable to contact any of the other Hawaiian islands or the US mainland.
By far the most spectacular after-effect of the Starfish Prime nuclear test was the expansive and long-lasting aurora it generated across much of the Pacific. This was a result of electrons raining down upon and colliding with Earth’s atmosphere, generating a dazzling visual effect resembling fireworks. The flashy side effect was essentially an artificial recreation of the process behind the aurora borealis.
From its surface extruded great white fingers, resembling cirro-stratus clouds, which rose to 40 degrees above the horizon in sweeping arcs turning downward toward the poles and disappearing in seconds to be replaced by spectacular concentric cirrus like rings moving out from the blast at tremendous initial velocity, finally stopping when the outermost ring was 50 degrees overhead... As the purplish light turned to magenta and began to fade at the point of burst, a bright red glow began to develop on the horizon at a direction 50 degrees north of east and simultaneously 50 degrees south of east expanding inward and upward until the whole eastern sky was a dull burning red semicircle 100 degrees north to south and halfway to the zenith obliterating some of the lesser stars. This condition, interspersed with tremendous white rainbows, persisted no less than 90 minutes.
The aurora resulting from the Starfish Prime explosion was enormously far-reaching. Electrons clashed with atoms all over the Pacific Ocean or, as the Department of Defense described it:
[A] very large area of the Pacific was illuminated by the auroral phenomena, from far south of the south magnetic conjugate area (Tongatapu) through the burst area to far north of the north conjugate area (French Frigate Shoals).
The blast and its after-effects were brilliant enough to be captured by several cameras back on Earth. The aurora even showed up on the opposite side of the equator from the launch site. Interestingly enough, the blast and its after-effects could be seen by many but nobody heard it.