62.7333°N, 11.2000°E.
Phenomenon of unexplained luminous objects observed in the Hessdalen valley of central Norway, documented continuously since the early 1980s with a peak frequency of 15–20 sightings per week between 1981 and 1984. Sightings persist at lower frequency. Project Hessdalen, established by Erling Strand and Bjorn Hauge in 1983, has maintained automated optical, radar, and magnetic monitoring stations in the valley since 1998. Recorded characteristics include white, yellow, and red luminous balls of light persisting from seconds to hours, traveling at velocities up to 30,000 km/h, and occasionally splitting or merging. Hypotheses tested include ionized dust from the iron-rich valley floor, atmospheric plasma from the metallic ore content of the bedrock (Teodorani 2004), and battery-effect electrical discharge in the valley's natural geometry. No single explanation accounts for all observed phenomena.
A Norwegian valley produces unexplained lights frequently enough that Norwegian universities run permanent equipment there — and forty years of monitoring still cannot say what they are.