A dark moonless night on Cleary Summit, north of Fairbanks, Alaska. Looking westward beneath the auroral wall, the delicate dance of light could barely illuminate the snow.
As noted by the photographer “Auroras, standing atop the atmosphere about 100km overhead, can often reach up into the heavens another 1000 kilometers. The lower portion of the auroral wall, the first 400km of aurora height, the light is green, but once the wall grows in height and pushes above the 400km point, anything above that turns a beautiful red. So a full blown 1000km aurora wall will have 400km of green light on the lower part of the wall, and will have about 600km of red light standing above that. And when you end up looking through both the green light and some distant red, the color of the two mixed will give the look of yellow light, as red and green light make yellow. Hence some of the colors you can see here”.