It was 4:05 a.m. on Sept. 20, 1977. Something serious was happening over the skies of Petrozavodsk in northwest Russia.

A group of dockworkers on the early shift that morning say they saw a blinding light emerge from the direction of Lake Onega. As it approached Petrozavodsk, the light took on the appearance of a glimmering jellyfish, before slowing to a hover and unleashing a salvo of ultra-thin beams of light.

The dockworkers were left wondering what they had seen. Some were concerned they were witnessing a nuclear attack: This was, after all, the height of the Cold War.

But that did not explain what came next. After 12 puzzling minutes, the shining object transformed into a bright semicircle and jetted off back toward Lake Onega. Rather than disappearing over the horizon, it appeared to veer upward, before punching a burning red hole in the clouds, and disappearing into the abyss.

No one died, and the United States, it seemed, was not involved.

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