Hessdalen Valley

The Hessdalen lights are anomalous luminous phenomena observed in a 12-kilometre stretch of the Hessdalen valley in central Norway. The lights — white, yellow, or red, sometimes the size of a car — have been witnessed floating above and below the horizon at varying speeds and directions, occasionally remaining stationary for over an hour.

The sightings intensified between 1981 and 1985, prompting Project Hessdalen, a scientific survey established in 1983 that has operated continuously since. Researchers have recorded the lights on radar, infrared cameras, seismographs, and spectrographs. Leading hypotheses involve combustion of dust clouds composed of scandium, hydrogen, and sodium ionised by piezoelectric effects from the valley's ore-bearing geology — though no model fully accounts for the behaviour of all observed lights.