In spite of on-going research there is no convincing explanation to the origin of these lights. However, there are numerous working hypothesis.
One explanation attributes the phenomenon to an incompletely understood combustion process in the air involving clouds of dust from the valley floor containing scandium. Some sightings, though, have been identified as misperceptions of astronomical bodies, aircraft, car headlights, and mirages. One recent theory suggests that HL are formed by a cluster of macroscopic Coulomb crystals in a plasma produced by the ionization of air and dust by alpha particles during radon decay in the dusty atmosphere. Several physical properties (oscillation, geometric structure, and light spectrum) observed in HL phenomenon can be explained through the dust plasma model  Radon decay produces alpha particles (responsible by helium emissions in HL spectrum) and radioactive elements such as polonium. Teodorani (2004) showed a HL occurrence where a higher level of radioactivity on rocks was detected near the area where a large light ball was reported. In fact, when radon is released into air, its solid decay products readily attach to airborne dust. .
- Hessdalen lights - Wondermondo
- http://www.itacomm.net/ph/2007_HAUGE.pdf - [PDF][Archived]
- http://www.itacomm.net/ph/rebuttal.pdf - [PDF][Archived]
- http://www.scientificexploration.org/journal/jse_18_2_teodorani.pdf - [PDF][Archived]
- http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf - [PDF][Archived]
- Teodorani M. (2004) A Long-Term Scientific Survey of the Hessdalen Phenomenon. Journal of Scientific Exploration. 18 (2). 217-251.
- Scientific Exploration