Hessdalen Lights: From 19th-Century Sightings to Modern Scientific Monitoring and Ongoing Inquiry

To the point

The Hessdalen lights are unexplained luminous phenomena seen in the Hessdalen Valley of central Norway since the 19th century, studied by Project Hessdalen and the Hessdalen Automatic Measurement Station with instruments since the 1980s to document sightings, which have taken many forms and prompted a range of natural and even extraterrestrial explanations, but no single cause has gained universal acceptance and sightings have declined in recent years.