Starship Asterisk*

Colorful Airglow Bands Surround Milky Way

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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Extraordinary, stunning image. Wow.

APOD Robot wrote: ↑Tue Mar 06, 2018 5:06 am 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.

There also appears to be some purple airglow as well. Is it's sorce known?

Bruce

Gorgeous backdrop from China of a 2017 Buick Envision.

Nice picture. Anyone can see M31 and M33!!!

BDanielMayfield wrote: ↑Tue Mar 06, 2018 5:36 am

APOD Robot wrote: ↑Tue Mar 06, 2018 5:06 am
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.

There also appears to be some purple airglow as well. Is it's source known?

Based on the spectrum from: https://www.atoptics.co.uk/highsky/airglow2.htm most of
the colors would come from oxygen atoms (with only deep red coming from hydroxyl molecules).

Beautiful; worthy of being a wallpaper!

Can someone please explain the part about storms causing gravity waves? I thought gravity waves were only recently proven to exist.

Zuben L. Genubi wrote: ↑Tue Mar 06, 2018 4:36 pm
Can someone please explain the part about storms causing gravity waves?
I thought gravity waves were only recently proven to exist.

Gravitational waves (i.e., propagating ripples in spacetime) were only recently observed to exist.

Gravity waves (i.e., propagating disturbances in a fluid caused primarily by gravitational restoring forces)
have been known since humans first observed ocean waves.

So giant Black Holes eat dark matter to get so big so fast ? Getting schooled here big time. Back to admiring today's APOD and having a cup of brew !

ta152h0 wrote: ↑Tue Mar 06, 2018 7:56 pm So giant Black Holes eat dark matter to get so big so fast ? Getting schooled here big time. Back to admiring today's APOD and having a cup of brew !

A brew and the wonders from APOD is the true meaning of life!

neufer wrote: ↑Tue Mar 06, 2018 12:56 pm

BDanielMayfield wrote: ↑Tue Mar 06, 2018 5:36 am

APOD Robot wrote: ↑Tue Mar 06, 2018 5:06 am
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.

There also appears to be some purple airglow as well. Is it's source known?

Based on the spectrum from: https://www.atoptics.co.uk/highsky/airglow2.htm most of
the colors would come from oxygen atoms (with only deep red coming from hydroxyl molecules).

Thanks Art. That reference was helpful. From it it appears that the purple color is coming from O₂ molecules.

Bruce