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On the night of 9 July 1962 a number of beach front hotels in Honolulu, Hawaii were throwing “rainbow bomb” parties; gathering sky gazers to the rooftops to prepare for a sight seldom seen in the South Pacific: the aurora.

Aurora is typically caused by a Coronal Mass Ejection (CME) from the sun, but in 1962 there were no instruments capable of detecting an incoming CME. But they didn’t need to predict an aurora, because they were going to create one. Specifically, the Defense Atomic Support Agency and the Atomic Energy Commission were creating the aurora by means of a suborbital nuclear detonation.

The test was codenamed Starfish Prime, and was part of Operation Dominic, a series of tests designed to test the abilities of nuclear weapons in space.

The W49 thermonuclear warhead was launched on the nose of a Thor rocket. The warhead detonated 248.5 miles above Johnston Island⁠⁠—an altitude that is considered outer space. The yield of the blast was 1.5 Megatons, but there was no fireball. There is no air at that altitude to ignite. That is not to say, however, that there were no visual effects.

Quoting Cecil R. Coale, PhD , who observed the flash from Canton Island:

Then a brilliant white flash erased the darkness like a photoflash. Then the entire sky turned light green for about a second. In several more seconds, a deep red aurora, several moon diameters in size, formed where the blast had been. A white plasma jet came slowly out of the top of the red aurora (over Johnston Island) and painted a white stripe across the sky from north to south in about one minute. A deep red aurora appeared over Samoa at the south end of the white plasma jet. This visual display lasted for perhaps ten minutes before slowly fading. There was no sound at all.

As spectacular as the sight was, it was the invisible features of the blast that were the most impressive. Not only was the sky illuminated, but in Hawaii alone 300 street lights failed, TV and radios malfunctioned, burglar alarms went off, and several power lines fused. In low Earth orbit 3 satellites were immediately disabled, and some artificial radiation bands were created that eventually disabled 1/3 of all low-orbiting satellites.

Obviously the aurora effect was predicted, but most of the rest came as a surprise. Unfortunately the government workers failed to arrange for any rockets or equipment to follow the bomb and study the aftereffects of the test.