Starship Asterisk*

Airglow Sky over France

Explanation: This unusual sky was both familiar and unfamiliar. The photographer's mission was to capture the arch of the familiar central band of our Milky Way Galaxy over a picturesque medieval manor. The surprise was that on this January evening, the foreground sky was found glowing in a beautiful but unfamiliar manner. The striped bands are called airglow and they result from air high in Earth's atmosphere being excited by the Sun's light and emitting a faint light of its own. The bands cross the entire sky -- their curved appearance is due to the extremely wide angle of the camera lens. In the foreground lies Château de Losse in southwest France. Other familiar sky delights dot the distant background including the bright white star Sirius, the orange planet Mars, the blue Pleiades star cluster, the red California Nebula, and, on the far right, the extended Andromeda Galaxy. The initial mission was also successful: across the top of the frame is the arching band of our Milky Way.

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The label "Sirius" is placed on the wrong star!

I think you have miss-identified Sirius.

NorbVor wrote: ↑Wed Feb 15, 2023 7:14 am The label "Sirius" is placed on the wrong star!

Yes, that star must be Procyon. Sirius, I think, is the bright star farther below somewhat above the large tree in the foreground. The rather bright star near the top left could be Pollux.

Holger Nielsen wrote: ↑Wed Feb 15, 2023 8:37 am

NorbVor wrote: ↑Wed Feb 15, 2023 7:14 am The label "Sirius" is placed on the wrong star!

Yes, that star must be Procyon. Sirius, I think, is the bright star farther below somewhat above the large tree in the foreground. The rather bright star near the top left could be Pollux.

Indeed, the caption got the position of Sirius wrong. And you may be right about Pollux.


Ann

Interesting that our observant humans here quickly picked up the misplaced Sirius. The ChatGPT AI that rewrote the APOD description apparently did not notice the error.

NorbVor wrote: ↑Wed Feb 15, 2023 7:14 am The label "Sirius" is placed on the wrong star!

Yes, my bad. Thanks to everyone including Ann. The annotation has now been fixed on the main NASA APOD. I apologize for the mistake.
- RJN

Why is Andromeda described as "the extended Andromeda Galaxy" here?

Beautiful!!!!

johnnydeep wrote: ↑Wed Feb 15, 2023 4:14 pm Why is Andromeda described as "the extended Andromeda Galaxy" here?

at this moderate exposure Andromeda is in fact presented in a short version

I wonder what is airglow waves' direction. East to West?

VictorBorun wrote: ↑Wed Feb 15, 2023 10:23 pm

johnnydeep wrote: ↑Wed Feb 15, 2023 4:14 pm Why is Andromeda described as "the extended Andromeda Galaxy" here?

at this moderate exposure Andromeda is in fact presented in a short version

I do understand that the longer the exposure, the larger (or "extended") Andromeda appears. But I see no point in using the 'extended' descriptor in this case. As you said, Andromeda doesn't look particularly "extended" to me either!

APOD Robot wrote: ↑Wed Feb 15, 2023 5:07 amThe striped bands are called airglow and they result from air high in Earth's atmosphere being excited by the Sun's light and emitting a faint light of its own. The bands cross the entire sky …

Wikipedia wrote:Even at the best ground-based observatories, airglow limits the photosensitivity of optical telescopes. Partly for this reason, space telescopes like Hubble can observe much fainter objects than current ground-based telescopes at visible wavelengths.

Does it glow all night? Every night? Everywhere (e.g. above Atacama, Hawaii, Canary Islands too)? With the same intensity? How do scientific ground based telescopes deal with the glow? From the photo, it seems to be much brighter than other very faint things.

VictorBorun wrote: ↑Wed Feb 15, 2023 10:25 pm I wonder what is airglow waves' direction. East to West?

I'm not sure they move in a particular direction. See the Youtube video below about waves in water:


Ann

Case wrote: ↑Thu Feb 16, 2023 2:36 am

APOD Robot wrote: ↑Wed Feb 15, 2023 5:07 amThe striped bands are called airglow and they result from air high in Earth's atmosphere being excited by the Sun's light and emitting a faint light of its own. The bands cross the entire sky …

Wikipedia wrote:Even at the best ground-based observatories, airglow limits the photosensitivity of optical telescopes. Partly for this reason, space telescopes like Hubble can observe much fainter objects than current ground-based telescopes at visible wavelengths.

Does it glow all night? Every night? Everywhere (e.g. above Atacama, Hawaii, Canary Islands too)? With the same intensity? How do scientific ground based telescopes deal with the glow? From the photo, it seems to be much brighter than other very faint things.

Airglow is always present, everywhere. It is what limits the dimmest thing that can be seen at any site not impacted by artificial light pollution. It varies in intensity. Imagers deal with the glow by subtracting it off the signal as background and living with its noise component.

Ann wrote: ↑Thu Feb 16, 2023 5:10 am

VictorBorun wrote: ↑Wed Feb 15, 2023 10:25 pm I wonder what is airglow waves' direction. East to West?

I'm not sure they move in a particular direction. See the Youtube video below about waves in water:

Click to play embedded YouTube video.

Ann

well, the airglow waves in the APOD do have two points of infinite distance convergence, and in principle we could relate them to East, West and such ...