21. The Hessdalen Lights
Location: Hessdalen valley in the municipality of Holtålen in Sør-Trøndelag county, Norway.
The Hessdalen light most often appears as a bright white or yellow light of unknown origin standing or floating above the ground level. Sometimes the light can be seen for more than one hour. There are several other types of unexplained lights observed in the Hessdalen valley. Unusual lights have been reported in the region since the 1940s or earlier. Especially high activity of Hessdalen lights took place from December 1981 until the summer of 1984 when lights were observed 15–20 times per week. The frequency of the lights caused a gathering of numerous tourists staying there overnight to see the phenomenon. Since then, the activity has decreased and now[when?] the lights are observed some 10–20 times per year. Several explanations have been put forward but none seem to provide a clear concept of the phenomenon.