Why the U.S. once set off a nuclear bomb in space

National Geographic ^ | 15 July | BRIAN GUTIERREZ

[DUMBGRUNT]

Spectators were also holding “watch-the-bomb parties” in Hawaii, as the countdown was broadcast over shortwave radio. Photographers aimed their lenses toward the horizon and debated the best camera settings for capturing a thermonuclear explosion in outer space. It turned out that the blast—a 1.4 megaton bomb, 500 times as powerful as the one that fell on Hiroshima—was not subtle.

“When that nuclear weapon went off, the whole sky lit up in every direction. It looked like noon,”

“It looked as though the heavens had belched forth a new sun that flared briefly, but long enough to set the sky on fire,” according to one account in the Hilo Tribune-Herald. An accompanying electromagnetic pulse washed out radio stations, set off an emergency siren, and caused streetlights to black out in Hawaii.

I told my dad years later, ‘You know, if I knew I was going to become a nuclear weapon physicist, I would have paid more attention,’” he says.

There is no mushroom cloud or double flash. People on the ground don’t feel a shock wave or hear any sound. There’s just a bright ball of plasma

This unexpected “Starfish belt,” which lingered for at least 10 years, destroyed Telstar 1, the first satellite to broadcast a live television signal, and Ariel-1, Britain’s first satellite.

The largest geomagnetic storm ever recorded, called the Carrington Event, hit Earth in 1859. It caused auroras over Australia and gave electrical shocks to telegraph operators in America.

[IndispensableDestiny]

Part of it shows the high-altitude tests conducted at Johnston Island. One of them knocked out power over a large area of the pacific from the EMP effect.

Starfish Prime (the article) was launched from Johnston Atoll. It had the effects you mentioned.