July 9, 1962 - The United States set off a thermonuclear explosion high over Johnston Island in the Pacific early today. It released a powerful flash of energy that lit up the night skies from Hawaii to New Zealand. The explosion, the most powerful ever conducted on the fringes of outer space, produced what are being described as the most spectacular, far-flung effects of any man-made event in history. Although announcements did not specify the altitude, it was understood that the blast took place at about 200 miles. That would place it in the upper layer of the ionosphere, the electrically charged region in the upper atmosphere. In Hawaii, some 700 miles northeast of Johnston Island, people stood in awe as the overcast night sky was suddenly turned into day in a six-minute glare of light from the flash of the explosion. At Auckland, New Zealand, 3,000 miles southwest of Johnston Island, an artificial aurora spread a luminous red band over the northern horizon, laced with quivering white shafts of light. Radio communications across the Pacific were temporarily disrupted as the explosion upset the normal balance in the ionosphere.
