Museum of Time
a night in the woods
A clear and dark August night near the small village of Hoorn on the island of Terschelling.
Low over the northern horizon a weak whitish glow was visible in the big dipper (Ursa Major, grote beer). In the photograph it turned out to be blue sunlit nitrogen aurora at a height of 400 - 800 kilometers in the atmosphere, far away above mid-Norway.
  During that night, the auroral display became a bit brighter but still no colors were seen with the eye, even after three hours of dark adaptation. The aurora had moved towards southern Norway and low over the Terschelling horizon the green and red colors of oxygen also appeared in the photographs.

Blue and red light mixed to pink/violet and the green and red aurora mixed to yellow/orange. Without making any sound, clouds formed over the Northsea and began eating the northern lights.
As darkness ended, a final exposure of six minutes showed that behind the clouds, the upper atmosphere was still glowing from aurora.