Starship Asterisk*

[quote=neufer post_id=280405 time=1520340968 user_id=124483]
[quote=BDanielMayfield post_id=280401 time=1520314572 user_id=139536]
[quote="APOD Robot" post_id=280400 time=1520312811 user_id=128559]

Red airglow likely originates from [url=https://en.wikipedia.org/wiki/Hydroxyl]OH molecules[/url] about 87-kilometers high, excited by [url=https://science.nasa.gov/ems/10_ultravioletwaves]ultraviolet light[/url] from the Sun, while orange and green [url=http://www.pnas.org/content/112/49/E6728.abstract]airglow[/url] is likely caused by [url=http://periodic.lanl.gov/11.shtml]sodium[/url] and [url=http://periodic.lanl.gov/8.shtml]oxygen[/url] atoms slightly higher up.[/quote]

There also appears to be some purple airglow as well. Is it's source known?[/quote]
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).
[/quote]
Thanks Art. That reference was helpful. From it it appears that the purple color is coming from O[sub]2[/sub] molecules.

Bruce

[quote=ta152h0 post_id=280418 time=1520366179 user_id=100922]
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 !
[/quote]

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

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 !

[quote="Zuben L. Genubi" post_id=280414 time=1520354162]

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

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

Beautiful; worthy of being a wallpaper! 8-) :D

[quote=BDanielMayfield post_id=280401 time=1520314572 user_id=139536]
[quote="APOD Robot" post_id=280400 time=1520312811 user_id=128559]

Red airglow likely originates from [url=https://en.wikipedia.org/wiki/Hydroxyl]OH molecules[/url] about 87-kilometers high, excited by [url=https://science.nasa.gov/ems/10_ultravioletwaves]ultraviolet light[/url] from the Sun, while orange and green [url=http://www.pnas.org/content/112/49/E6728.abstract]airglow[/url] is likely caused by [url=http://periodic.lanl.gov/11.shtml]sodium[/url] and [url=http://periodic.lanl.gov/8.shtml]oxygen[/url] atoms slightly higher up.[/quote]

There also appears to be some purple airglow as well. Is it's source known?[/quote]
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).

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

Gorgeous backdrop from China of a 2017 Buick Envision.

Extraordinary, stunning image. Wow.

[quote="APOD Robot" post_id=280400 time=1520312811 user_id=128559]
Red airglow likely originates from [url=https://en.wikipedia.org/wiki/Hydroxyl]OH molecules[/url] about 87-kilometers high, excited by [url=https://science.nasa.gov/ems/10_ultravioletwaves]ultraviolet light[/url] from the Sun, while orange and green [url=http://www.pnas.org/content/112/49/E6728.abstract]airglow[/url] is likely caused by [url=http://periodic.lanl.gov/11.shtml]sodium[/url] and [url=http://periodic.lanl.gov/8.shtml]oxygen[/url] atoms slightly higher up.[/quote]

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

Bruce

[url=https://apod.nasa.gov/apod/ap180306.html] [img]https://apod.nasa.gov/apod/calendar/S_180306.jpg[/img] [size=150]Colorful Airglow Bands Surround Milky Way[/size][/url]

[b] Explanation: [/b] Why would the sky glow like a giant repeating rainbow? [url=http://www.atoptics.co.uk/highsky/airglow2.htm]Airglow[/url]. 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 [url=http://www.nasa.gov/mission_pages/sunearth/science/atmosphere-layers2.html]Earth's atmosphere[/url]. These [url=https://en.wikipedia.org/wiki/Gravity_wave]gravity waves[/url] are [url=http://www.atoptics.co.uk/highsky/hgrav.htm]oscillations in air[/url] analogous to those created when a [url=https://www.youtube.com/watch?v=T9QwiBFN9gI]rock is thrown in calm water[/url]. Red airglow likely originates from [url=https://en.wikipedia.org/wiki/Hydroxyl]OH molecules[/url] about 87-kilometers high, excited by [url=https://science.nasa.gov/ems/10_ultravioletwaves]ultraviolet light[/url] from the Sun, while orange and green [url=http://www.pnas.org/content/112/49/E6728.abstract]airglow[/url] is likely caused by [url=http://periodic.lanl.gov/11.shtml]sodium[/url] and [url=http://periodic.lanl.gov/8.shtml]oxygen[/url] atoms slightly higher up. While driving near [url=http://www.globaltimes.cn/content/795907.shtml]Keluke Lake[/url] in [url=https://en.wikipedia.org/wiki/Qinghai]Qinghai Provence[/url] in [url=https://en.wikipedia.org/wiki/China]China[/url], the photographer originally noticed mainly the impressive central band of the [url=https://apod.nasa.gov/apod/ap080713.html]Milky Way Galaxy[/url]. Stopping to photograph it, surprisingly, the resulting sensitive camera image showed [url=https://apod.nasa.gov/apod/ap170221.html]airglow bands[/url] 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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