Science: In Arctic Twilight

U.S. airmen flying the far north in search of weather data have often been bedeviled and bewildered by the arctic twilight. During the long arctic winter, the navigators of the 375th Squadron, at Eielson Airforce Base near Fairbanks, Alaska, had no trouble. They used special "grid" maps* and flew by the stars, visible all the time. During the arctic summer, they flew by the never-setting sun.

Blinding Twilight. But during the spring and fall, both the sun and the stars often failed them. The sun remained invisible below the horizon for many hours each day, but it gave enough light to blot...

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