The Petrozavodsk Phenomenon: the Jellyfish over Karelia

September 1977. Petrozavodsk, capital of the Karelian ASSR, sat on the western shore of Lake Onega. Around 203,000 people lived there. In the small hours of 20 September, strange reports began to arrive from across the north. Medvezhyegorsk at 01:00. Loukhi at 02:30. In Helsinki, police described "a bright ball of fire" hovering over the airport for about 4 minutes.

About 04:00. Dockworkers saw a bright, jellyfish-like light approaching Petrozavodsk from Lake Onega. TASS correspondent Nikolai Milov wrote of a "huge star" that "flared up in the dark sky", "impulsively sending shafts of light to the Earth". It moved slowly toward the city. Then it spread over it like a jellyfish, "showering the city with a multitude of very fine rays which created an image of pouring rain".

It made no sound. A red object gave off a bluish-white glow, and the ground was lit about as brightly as under a full moon. It hung over the city for about 5 minutes. Then the rays stopped. The object became a "bright semicircle" and moved toward the lake. By one account, it punched a red hole through the clouds.

Others saw stranger things. Writer and philosopher Yuri Linnik, at his telescope near Namoyevo, saw a lens-shaped object, dark amethyst in colour, with 16 "nozzles" sending out pulsating red rays. Near Kurkijoki, engineer A. Novozhilov watched an airship-like body about 100 m long, its facets glowing like windows. It released a glowing ball that came down behind a forest. A Tu-154 crew saw a luminous sphere at 12 km.

Milov's report ran in Pravda and Izvestiya. Northern European governments wrote to the USSR Academy of Sciences, asking whether Soviet weapons tests were responsible. Lev Gindilis of the Sternberg Institute led the first analysis. A preliminary report of 20 October 1977 concluded that "based on the available data, it is unfeasible to satisfactorily understand the observed phenomenon". In January 1978, an expert group was sent to Karelia.

The case helped launch Setka AN, known as "The Network", run by the Ministry of Defence and the Academy of Sciences from 1978 to 1990. Yuli Platov led the Academy side. It gathered about 3,000 reports. About 300 were judged genuinely anomalous. It found no evidence of alien visitation.

At 01:01 UTC that night, a Vostok-2M rocket lifted off from the Plesetsk Cosmodrome carrying Kosmos-955. Western press tied the sighting to the launch within hours. James Oberg traced it to Plesetsk. In Oberg's view, the saucer story served Soviet censors by hiding a launch site Moscow denied. The USSR acknowledged the Northern Cosmodrome in 1983. Platov later explained the wide glow as the vehicle climbing out of Earth's shadow into sunlight.

The doubts never fully faded. Felix Ziegel noted that aurorae do not occur below 100 km and that chemiluminescent clouds cannot move against the wind. Gindilis said the direction of motion did not fit the launch. And several reports were timed before liftoff.

Today, sunlit exhaust plumes after launches are called "space jellyfish". Petrozavodsk remains the case that pushed the Soviet state into a long, secret study of UFOs. It returned to screens in 2021 in Netflix's Top Secret UFO Projects: Declassified.