What happened
Before dawn on September 20, 1977, residents of Petrozavodsk in Soviet Karelia saw a bright object in the sky that spread out over the city like a giant jellyfish and “showered” it with beams of light resembling a downpour. Similar lights were reported that night over a vast area – from Copenhagen and Helsinki to distant regions of the USSR. The story reached the Soviet press, and representatives of the governments of the Nordic countries asked the USSR Academy of Sciences whether it had been a weapons test and whether the phenomenon posed a threat to the environment. The Academy prepared a preliminary report with hundreds of eyewitness accounts as well as radar and meteorological data. The event contributed to the launch of a state program in the USSR to study anomalous atmospheric phenomena.
Witnesses
Hundreds of Petrozavodsk residents and witnesses in Finland and other regions of the USSR; the accounts were collected by scientists from the USSR Academy of Sciences.
Explanations and hypotheses
The most widely accepted explanation links the phenomenon to the launch of a rocket that carried the Kosmos-955 satellite into orbit from the Plesetsk Cosmodrome that night: sunlit exhaust gases and a cloud of fuel could have produced the image of a “jellyfish” and descending rays. The preliminary report for the USSR Academy of Sciences stated, however, that the data collected did not allow a satisfactory understanding of the phenomenon, so some researchers still consider the case open.
Disputed A likely explanation exists, but some of the facts are still disputed.
More: Wikipedia (pl) Wikipedia (en)