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Credit & Copyright: Tamas Ladanyi
(TWAN)
Explanation:
In this serene night skyscape,
the Milky Way's graceful arc stretches over prominent
peaks in the Italian Alps known as Tre Cime di Lavaredo.
A 180 degree wide-angle panorama made in four exposures on
August 24, the scene does look to the north and the sky is suffused
with an eerie greenish light.
Still, the subtle glowing bands are
not aurorae, but airglow.
Unlike aurorae 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, and
found around the globe.
The chemical energy is provided by the Sun's extreme ultraviolet
radiation.
Like aurorae, the greenish hue of this airglow does originate
at altitudes of 100 kilometers or so dominated by
emission from excited oxygen atoms.
More easily seen
near the horizon, airglow keeps the
night sky from ever being
completely dark.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Milky Way
Publications with words: Milky Way
See also:
- APOD: 2023 December 12 Á Aurora and Milky Way over Norway
- Milky Way Rising
- APOD: 2023 July 18 Á Milky Way above La Palma Observatory
- APOD: 2023 July 16 Á Meteor and Milky Way over the Alps
- APOD: 2023 July 2 Á Milky Way and Aurora over Antarctica
- APOD: 2023 June 20 Á The Nandu in the Milky Way
- APOD: 2023 May 29 Á Milky Way over a Turquoise Wonderland