Hessdalen is a valley in Norway, wehre there live no more than 200 people. In this valley, many years, a phenomenon manifested itself, which unbtil this time did not have an explanation. The sky is seen, actually, with a certain frequency ,a strange lights, which take different forms (although the most commmon is the globe), sizes and colors. The lights can be fixed or intermittent, or moving buildings, fxed air, the mountains or on the grond. Tehir duration can be from several seocnds to seveeral minyutes. The reality of this phenomenon is attested by eyewitnesses, but also by the photographs taken, coated or analyss of radio waves.
For over the years have given different explanations, but most are findinmg that it copmes to aliens. Scientists who went to Hesdsdalen and have studied the phenomenon say that thewre may be physical manifestations plamsa or piezoelectric. Piezoelectricitatea is the property of certain materials pressent in the soil (especially crystalls), genrate a pootential differenvce, if they are subjected to mechanical forces: compression, stretching or breaking. This can cause the lgihts, or may be concentratoins of power, which produces light at certian times. But do not exclude correllation with sun activity (spots and solar wind) in the presence of radon gas present in low atmospohere. Many assumptions that make this mystery to be elucidated.