Hessdalen Lights. In the Hessdalen Valley of Norway, strange lights have been spotted since the 1940s. These lights are white or yellow and float above ground level. Between 1981 to 1984, they were observed around 20 times per week, but these days its maybe 20 times per year. No explanation has come forth as of yet.*
If you're interested in some hypotheses, Wikipedia has some here.
Or check out this video:
The truth is out there. Would you like UFOs to be visitors from another planet?