The Northern Lights, also known as the Aurora Borealis, can display a range of colors. The most common color seen from the ground is green, which is produced when charged particles collide with oxygen molecules at altitudes of 100 to 300 km¹. Occasionally, the lower edge of an aurora will have a pink or dark red fringe, which is produced by nitrogen molecules at altitudes of around 100 km. A bit higher in the atmosphere (at altitudes of 300 to 400 km), collisions with oxygen atoms produce red auroras. Finally, hydrogen and helium molecules can produce blue and purple auroras, but these colors tend to be difficult for our eyes to see against the night sky¹.
Source: Conversation with Bing, 8/8/2023
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