Borderline experience in the far North

Imagine you need to go for the privy when it's minus 30°C and pitch dark outside; it is not really a pleasure. But if you finally overcome your weaker self and are rewarded with this awesome Aurora borealis you totally forget about the extreme conditions. You just stand still for one hour on the frozen river Teno, which is marking the border between Finland and Norway. Your heart admires the present you just received for your 30th birthday, your scientific brain is thinking, was it oxygen emitting energy at 557.7nm wavelength causing the green hue?