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Orange Aurora

26 October 2023

At https://spaceweather.com – see the archive for October 25th 2023. We have an image of an auroral display over Canada, captured on camera by Harlan Thomas over Sibbold Pond, west of Calgary, on October 9th. The aurora contained the colour of orange – in what is a beautiful display [go to the link]. A pillar of orange dominates the image, and the photographer said it continued to glow for over 20 minutes. The experts at Space Weather note that auroras get their colour from atoms and molecules in Earth’s atmospherre. During geomagnetic storms energetic particles rain down from space, striking the air and causing it to glow. Red, green, purple and pink aurora are well known induced colours, created by oxygen and nitrogen in the atmosphere. However, looking at the Harlan Thomas image one can see red auroras on top, overlapping green auroras further down. Red and green combined, may have produced the yellow and orange glow. Red aurora are formed by low energy electrons colliding with atomic oxygen at high altitudes. These electrons are excited and go on to produce red photons. Green aurora are formed by higher energy electrons penetrating deeper and colliding with oxygen at lower altitudes. These are excited into a state where they emit green photons. In between there can be a mixing of the two processes in order to create orange and yellow photons. In reality, it is both red and green auroras at the same time.

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