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Credit & Copyright: Xiaohan Wang
Explanation:
Why would the sky glow like a giant repeating rainbow?
Airglow.
Now air glows all of the time, but it is usually hard to see.
A disturbance however -- like an approaching storm --
may cause noticeable rippling in the
Earth's atmosphere.
These gravity waves are
oscillations in air analogous
to those created when a
rock is thrown in calm water.
Red airglow likely originates from
OH molecules
about 87-kilometers high, excited by
ultraviolet light from the Sun, while orange and green
airglow
is likely caused by
sodium and
oxygen atoms slightly higher up.
While driving near
Keluke Lake in
Qinghai Provence in
China,
the photographer originally noticed mainly the impressive central band of the
Milky Way Galaxy.
Stopping to photograph it, surprisingly, the resulting sensitive camera image showed
airglow bands to be quite prominent and span the entire
sky.
The featured image has been digitally enhanced to make the colors more vibrant.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day