Airglow at Črni Vrh Observatory
Unusual reddish airglow was captured on the night of 27. - 28. December 2016. The sky was bright for hours even to unaided eye, while long exposures with Canon EOS 700D camera and fisheye lens revealed streaks and patches of red glowing cloud-like features. This airglow is due to chemiluminescence, the production of light through chemical excitation. Red airglow emission is predominately from atmospheric oxygen atoms at extremely low densities, found high in the atmosphere at 150 - 300 km.