6. Hessdalen Lights

If you’re planning a trip to Norway, always remember to dress warm and pack extra mosquito repellant. Oh, and disregard any bright lights floating around at night – that’s just the Hessdalen Lights.

Apparently, sky-bound light displays of unknown origin can still be seen 1-2 times per month in the Hessdalen Valley region of Norway. They occur at various altitudes and hover for as long as 6 hours at a time, before they disappear.

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Scientists agree that Hessdalen Lights are natural phenomena, though that’s pretty much all we’ll ever know about them. There are numerous theories but none that explain why the lights appeared about 50 times more often from 1981 to mid-1983. During that time period, the mysterious phenomenon could be seen 2-4 times per day.