
In 1962, the US detonated a 1.4 megaton nuclear bomb 250 miles above the Pacific in a test called Starfish Prime, and the electromagnetic pulse knocked out streetlights, burglar alarms, and a telephone company microwave link in Honolulu nearly 900 miles away, on an island most engineers had assumed was safely out of range
On July 9, 1962, a Thor rocket carrying a W49 thermonuclear warhead detonated roughly 250 miles above Johnston Atoll in the central Pacific.







