On April 27, photographer Jeff Dai captured this stunning image of the skies over Tibet, following some powerful thunderstorms in Bangladesh. The colourful ripples of stars seem to form a luminescent spiral in a phenomenon known as “airglow.”
“The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins,” explains NASA, which selected Dai’s image as its “Astronomy Picture of the Day.” The light and colour produced during this airglow shot are the result of a chemical reaction taking place about 90 kilometers up in the sky.
“Chemical reactions produce the light like in a glow stick,” Bob Keesee, of the University of Albany, explained to NBC News, in reference to another airglow photo.
While the Northern Lights, or aurora, are only visible from certain vantage points, airglow can be seen anywhere in the world. Airglow, which NASA says “keeps the night sky from ever being completely dark,” is the light that hangs around even in a seemingly pitch black sky.
Here’s what airglow looks like from space, in an image captured from the International Space Station as it passed over Australia:
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