“At the end of 1981 through 1984, residents of the Valley became concerned and alarmed about strange, unexplained lights that appeared at many locations throughout the Valley. Hundreds of lights were observed. At the peak of activity, there were about 20 reports a week.” (Source)
According to the residents of the Hessdalen valley of Norway, mysterious glowing orbs hover over the water and, some say, recede when approached. Sometimes called “will-o-the-wisps,” eerie orbs like these have been observed the world over. However, the Hessdalen lights are unique - they are being scientifically monitored.
Since 1998, the Hessadeln AMS (Automatic Measurement System) has monitored the lights with a magnetometer, two black-and-white cameras, and one color camera. Since its inauguration, the station has recorded many pictures and even videos of the inexplicable luminous orbs.
The project is funded in part by a team of Italian chemists. Though many UFO-enthusiasts are following the recordings of the Hessdalen AMS, the goals of the project are not, in fact, extraterrestrial observation but simple scientific curiosity. From the official site: “Knowledge of the Hessdalen phenomenon may give us a better understanding of our world… Better knowledge of our world will give us a better understanding of the consequences of our treatment of the natural environment.”
Though the frequency of their appearances varies, on average the Hessdalen lights are observed roughly 20 times a year.