Vertical Aurora Columns Above Spruce Forest, Alaska
Interior Alaska
A tall vertical aurora borealis column with a band of rare red along its edge runs from the top of the frame down to the silhouette of a black spruce forest. Long vertical rays like this show up when the field lines are close to overhead, which happens when the auroral oval is right on top of you. In Interior Alaska that happens most clear winter nights. The red edge is oxygen emission from well above the main auroral layer, and it only shows up during active geomagnetic activity. Seeing it clearly next to the usual green is a sign of a good storm night. Aurora borealis, Alaska. Photo © copyright by Carl Donohue.
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