It's a bird! It's a plane! It's... something far more frightening. 'It' was code-named 'Starfish Prime,' a test conducted in the summer of 1962, when a 1.45-megaton nuclear weapon was launched 250 miles into space above the Pacific Ocean and then detonated.
The resulting nuclear explosion in space, reports Discover Magazine, was a pulse of energy so strong it affected electrical circuits, power lines, and streetlights in Hawaii, nearly 600 miles away.
The purpose of this test was, basically, just to see what would happen, notes HowStuffWorks. Specifically, researchers wanted examine how the explosion would affect the Van Allen Radiation Belts -- bands of high-energy protons and electrons that follow the Earth's natural magnetic field -- to see if they could be manipulated for national defense purposes.
Scientists learned plenty from the experiment, and bystanders from Hawaii to New Zealand were treated to a view of "rainbow skies," but according to NPR, this "greatest man-made light show" actually resulted from radioactive particles coming into contact with oxygen and nitrogen in Earth's atmosphere. And the particles took years to eventually return to normal levels.
Now, 50 years after Starfish Prime, a handful of nuclear non-proliferation treaties are in place to prevent similar experiments from ever happening again.
WATCH recently declassified footage from Starfish Prime, above. Video from various angles of the explosion begins at 8:07, preceded by an explanation of the experiment.