A series of celestial phenomena of disputed nature was observed in the western Soviet Union, Finland and Denmark.

The Petrozavodsk phenomenon was a series of celestial events of a disputed nature that occurred on 20 September 1977. The sightings were reported over a vast territory, from Copenhagen and Helsinki in the west to Vladivostok in the east. It is named after the city of Petrozavodsk in Russia, Soviet Union, where a glowing object was widely reported that showered the city with numerous rays.