A rare 'blood' Aurora fills the sky across the Northern Rockies. Red or ‘blood' aurora’s are created by oxygen atoms at an altitude of between 200–500 km (120-300miles) colliding in a high energy state and emitting red light at 630 nm. In contrast the more common green aurora are oxygen atoms at a lower altitude of 70-200km (40-120 miles) and lower energy state emitting light at 557.7 nm. In most cases to see a red aurora you need an extremely dark sky and to be looking from a lower latitude across the top layers of a distant high latitude aurora.

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