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8 natural mysteries that can't be explained

By: Melissa Breyer on Sept. 28, 2015, 1:01 p.m.
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Hessdalen lights

Over a valley in central Norway persists a phenomena that stokes the fire of UFO buffs far and wide. Known as the Hessdalen lights — named for the valley where they occur ‚ sightings of the strange balls of glowing luminosity have been reported since at least the 1940s, by some accounts as early as the 19th century. They come in a variety of colors and formations; sometimes they flash, sometimes they dart around quickly, sometimes they just hover. At their most active they appeared 10 to 20 times per week, but nobody knows what on heaven's name they are. A research effort, Project Hessdalen, was launched in 1983 by Østfold University College and at least six different types of energy states have now been identified, but the source of energy remains unknown. Whatever they are, they've earned Hessdalen the unofficial title of "center of UFO mania." See the lights in action below: