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Credit & Copyright: Dave Lane;
Rollover Annotation: Judy Schmidt
Explanation:
Why would the sky look like a giant fan?
Airglow.
The featured intermittent
green glow
appeared to rise from a lake through the arch of our
Milky Way Galaxy,
as captured during 2015 next to
Bryce Canyon in
Utah, USA.
The unusual
pattern was created by
atmospheric
gravity waves, ripples of alternating air pressure that can grow with height
as the air thins,
in this case about
90 kilometers
up.
Unlike auroras powered by collisions with
energetic charged particles and seen at high latitudes, airglow is due to
chemiluminescence, the
production of light in a chemical reaction.
More typically seen near the horizon,
airglow keeps the night sky from
ever being completely dark.
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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