Time after time the sky was filled by the most amazing patterns, including strong coronas in green and purple, but most noticable was the dominance of the very deep all-red auroras - a much deeper red then I have ever seen before!
The colour of the northern lights depend largely on the composition of gases in the Earth`s atmosphere. When charged particles from the solar wind hit the atoms and molecules in the atmosphere, they excite the atoms present and give off light that we see as auroras. Tonights deep-red auroras indicate that the particles from the solar wind interacted with oxygen at high altitudes (whereas the more "normal" greenish-yellow auroras are formed at lower altitudes). Neutral nitrogen is responsible for the purple colour often seen at the "edges" of the more common oxygen-green.
More about red auroras can be read here: http://www2.gi.alaska.edu/ScienceForum/ASF9/918.html
Deep red auroras as seen from a river around midnight. Orion can be seen to the right.
The lights from the nearby city Tromsø can be glimpsed to the left in the picture
Northern lights crown - corona
Later in the night, the auroras appeared so strong in colour that I had to