Astronaut's Photo Shows Earth's Glorious 'Airglow' Halo

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Astronaut Reid Wiseman tweeted a photo Monday morning that may be the most dramatic ever capture of the phenomenon known as "airglow," which appears as a lambent halo encompassing the Earth. And this mystical beauty has an interesting origin, too. Professor Bob Keesee, of the University of Albany, explained in an email to NBC News: "The upper orangeish layer is probably light emission from atomic sodium, which is deposited in the atmosphere by vaporizing meteroids seen as meteors in the night sky. Chemical reactions produce the light like in a glow stick." It could also be atomic oxygen, but the altitude and true color aren't easy to discern in the shot, he wrote.

The blue and fuzzy lower layers are probably moonlight being scattered by sulfuric acid droplets in the stratosphere, Keesee guessed. The things that look like spaceships are actually the ISS's solar panels seen from the side. The airglow effect is dim enough that it may not always be perceptible to a space traveler's naked eye. Wiseman's photo used a long exposure time, like what you might use on Earth to capture pictures of stars, to make the airglow visible. It may not be very sharp, but you try taking a clear picture at 17,100 miles per hour.

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