Seeing the northern lights, or the aurora borealis, as they are also known, is a jaw-dropping and mystical moment.

Theoretically, you can see the northern lights all over Norway. However, the best places are above the Arctic Circle in Northern Norway.

The northern lights belt hits Northern Norway in the Lofoten Islands, and follows the coast all the way up to the North Cape. This means that no other place on earth offers better chances of spotting the lights, and one location in this area might be as good as another. In fact, one often observes the same northern lights in the Lofoten as in Tromsø, just from a different angle. The driest weather, giving clear skies, is found inland, statistically providing the best chances, but with strong eastern winds, the coast can be clearer than inland areas.

Perhaps not so surprisingly, the northern lights' spectacle has given rise to as many legends as there have been people watching. Symbols linked to the northern lights are found on the Sami shamanistic drum. The phenomenon has several different names in Sami. It is, for instance, known as Guovssahas, which means "the light which can be heard". The northern lights were traditionally associated with sound by the Sami, the indigenous people of Norway. And during the Viking Age, the northern lights were said to be the armour of the Valkyrie warrior virgins, shedding a strange flickering light.

Reality, if not as poetic, is equally impressive. It is the sun that lies behind the formation of the auroras. During large solar explosions and flares, huge quantities of particles are thrown out of the sun and into deep space.

When the particles meet the Earth's magnetic shield, they are led towards a circle around the magnetic North Pole, where they interact with the upper layers of the atmosphere. The energy which is then released is the northern lights. All this happens approximatelty 100 kilometres above our heads.
Source