Observers describe the Auroras as impressive. First Nations peoples told tales to interpret their meaning.
Planet Earth is surrounded by a magnetic field. The magnetic field captures charged particles from outer space, and diverts them to the Earth's magnetic poles. When these charged particles interact with the upper atmosphere there are various kinds of exchanges of energy, resulting in the transmission of photons of various frequencies -- including visible light.
The source of most of the extraterrestrial charged particles is the solar wind. And the intensity of the aurora borealis, and a corresponding Aurora Australis around the south magnetic pole is directly related to the intensity of the solar wind.
- Alister Graham. Solar Outbursts - Storm Warning, Sky and Telescope, January 2000. Retrieved on 2008-08-26. “The flow of charged solar particles through the Earth's upper atmosphere is strong enough to ionise atmospheric particles, resulting in the eerie glow in the twilight sky known as the aurora, or the southern and northern lights. Because the interaction of magnetic fields and charged particles is greatest near the Earth's magnetic poles, the auroral phenomenon is more prevalent there than at middle latitudes.”