Image Credit & Copyright: Dave Lane; Rollover Annotation: Judy Schmidt
Sunday, January 31, 2016
NASA Photo of the Day
January 27:
An Airglow Fan from Lake to Sky
Image 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 last summer 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.
Image Credit & Copyright: Dave Lane; Rollover Annotation: Judy Schmidt
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