APOD: Cathedral, Mountain, Moon (2023 Dec 25)

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Expand view Topic review: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by EmanueleBalboni » Tue Jan 02, 2024 4:40 pm

EmanueleBalboni wrote: Sat Dec 30, 2023 3:53 pm
Chris Peterson wrote: Sat Dec 30, 2023 3:31 pm
nikkam wrote: Sat Dec 30, 2023 11:00 am

Visto che sei di Torino te lo spiego in italiano; io ho vissuto per anni in pieno centro con vista su Superga; decine di volte ho visto la Luna sorgere da dietro la Basilica, la luna come si sa ha estensione di circa 30' ed è più piccola della Basilica, entrambi questi oggetti sono 'fermi', cioè a uguale distanza sempre. Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Since you're from Turin, I'll explain it to you in Italian; I lived for years in the center with a view of Superga; dozens of times I have seen the Moon rise from behind the Basilica, the moon as we know has an extension of about 30' and is smaller than the Basilica, both of these objects are 'stationary', that is, always at the same distance. No lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.
The Moon and the basilica each subtend about a half degree, which is consistent with the camera being 82 km from the peak and 11 km from the basilica. Which would make everything in focus with any ordinary camera lens, and give exactly the geometry we see here. Nothing is "magnified", a term that doesn't even have any meaning in this context.
Let me be crystal clear: I'm an astrophyscist and a photographer; I've been there several times and took pictures of the Mount Viso, Superga and the Moon (I also posted some of the results here):
[img3]https://cosmoedintorni.org/wp-content/u ... erga-2.jpg[/img3]

Here there are two screenshots taken from PlanIt app, showing the alignment:
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
To have the Moon larger than Superga you simply have to move further from the basilica: Superga will appear smaller, while the Moon will be still the half degree you correctly wrote.
I pasted the same link for the two screenshots, sorry. Here the correct one:

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Liviux » Sat Dec 30, 2023 5:37 pm

Rauf wrote: Sat Dec 30, 2023 5:29 pm
Liviux wrote: Sat Dec 30, 2023 10:34 am That said, I want to add my congratulations to Giacomo Venturini for this exceptional and much evocative picture.
Bravissimo!
The picture's photographer is actually Valerio Minato.
Sorry, I got confused with today's photo author, who also deserves sincere congratulations.
While I'm at it, I wish to congratulate Emanuele Balboni, too, for his different vision of this remarkable alignment.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Guest » Sat Dec 30, 2023 5:30 pm

nikkam wrote: Sat Dec 30, 2023 11:00 am Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Invece è possibilissimo, praticamente con qualunque lente. Evidentemente non conosci il concetto di "distanza iperfocale": https://it.wikipedia.org/wiki/Distanza_iperfocale
Ad esempio: con una lente da 500mm di lunghezza focale, diaframma f/8, mettendo a fuoco a 1km di distanza risulta a fuoco tutto ciò che si trova fra 500m e l'infinito.

A margine, non capisco la necessità di mettere così aggressivamente in dubbio i risultati eccellenti raggiunti da qualcun altro, anziché congratularsene.
nikkam wrote: Sat Dec 30, 2023 11:00 amNo lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.
Actually, it is possible with almost any lens. You obviously do not know the concept of 'hyperfocal distance': https://en.wikipedia.org/wiki/Hyperfocal_distance
For example: with a 500mm focal length lens, f/8 diaphragm, focusing at a distance of 1km results in everything between 500m and infinity being in focus.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Rauf » Sat Dec 30, 2023 5:29 pm

Liviux wrote: Sat Dec 30, 2023 10:34 am That said, I want to add my congratulations to Giacomo Venturini for this exceptional and much evocative picture.
Bravissimo!
The picture's photographer is actually Valerio Minato.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by johnnydeep » Sat Dec 30, 2023 4:53 pm

EmanueleBalboni wrote: Sat Dec 30, 2023 3:53 pm
Chris Peterson wrote: Sat Dec 30, 2023 3:31 pm
nikkam wrote: Sat Dec 30, 2023 11:00 am

Visto che sei di Torino te lo spiego in italiano; io ho vissuto per anni in pieno centro con vista su Superga; decine di volte ho visto la Luna sorgere da dietro la Basilica, la luna come si sa ha estensione di circa 30' ed è più piccola della Basilica, entrambi questi oggetti sono 'fermi', cioè a uguale distanza sempre. Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Since you're from Turin, I'll explain it to you in Italian; I lived for years in the center with a view of Superga; dozens of times I have seen the Moon rise from behind the Basilica, the moon as we know has an extension of about 30' and is smaller than the Basilica, both of these objects are 'stationary', that is, always at the same distance. No lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.
The Moon and the basilica each subtend about a half degree, which is consistent with the camera being 82 km from the peak and 11 km from the basilica. Which would make everything in focus with any ordinary camera lens, and give exactly the geometry we see here. Nothing is "magnified", a term that doesn't even have any meaning in this context.
Let me be crystal clear: I'm an astrophyscist and a photographer; I've been there several times and took pictures of the Mount Viso, Superga and the Moon (I also posted some of the results here):
[img3]https://cosmoedintorni.org/wp-content/u ... erga-2.jpg[/img3]

Here there are two screenshots taken from PlanIt app, showing the alignment:
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
To have the Moon larger than Superga you simply have to move further from the basilica: Superga will appear smaller, while the Moon will be still the half degree you correctly wrote.
I'm neither an astrophysicist nor a photographer 😊, but comparing overlayed cutouts of the moon, mountain and basilica from your video to the APOD photo seems like a pretty close matchup to me:

moon mountain basilica.jpg

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by EmanueleBalboni » Sat Dec 30, 2023 3:53 pm

Chris Peterson wrote: Sat Dec 30, 2023 3:31 pm
nikkam wrote: Sat Dec 30, 2023 11:00 am
EmanueleBalboni wrote: Fri Dec 29, 2023 4:03 pm
I also live in Turin, and not knowing the place from which you can see the alignment does not allow you to say this shot is fake. Listen my advice: take a walk/ride/drive towards Castagneto Po in a beautiful day and see for yourself :ssmile:
Visto che sei di Torino te lo spiego in italiano; io ho vissuto per anni in pieno centro con vista su Superga; decine di volte ho visto la Luna sorgere da dietro la Basilica, la luna come si sa ha estensione di circa 30' ed è più piccola della Basilica, entrambi questi oggetti sono 'fermi', cioè a uguale distanza sempre. Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Since you're from Turin, I'll explain it to you in Italian; I lived for years in the center with a view of Superga; dozens of times I have seen the Moon rise from behind the Basilica, the moon as we know has an extension of about 30' and is smaller than the Basilica, both of these objects are 'stationary', that is, always at the same distance. No lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.
The Moon and the basilica each subtend about a half degree, which is consistent with the camera being 82 km from the peak and 11 km from the basilica. Which would make everything in focus with any ordinary camera lens, and give exactly the geometry we see here. Nothing is "magnified", a term that doesn't even have any meaning in this context.
Let me be crystal clear: I'm an astrophyscist and a photographer; I've been there several times and took pictures of the Mount Viso, Superga and the Moon (I also posted some of the results here):
[img3]https://cosmoedintorni.org/wp-content/u ... erga-2.jpg[/img3]

Here there are two screenshots taken from PlanIt app, showing the alignment:
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
[img3]https://cosmoedintorni.org/wp-content/u ... c2023.jpeg[/img3]
To have the Moon larger than Superga you simply have to move further from the basilica: Superga will appear smaller, while the Moon will be still the half degree you correctly wrote.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Sat Dec 30, 2023 3:31 pm

nikkam wrote: Sat Dec 30, 2023 11:00 am
EmanueleBalboni wrote: Fri Dec 29, 2023 4:03 pm
nikkam wrote: Thu Dec 28, 2023 6:29 am I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.
I also live in Turin, and not knowing the place from which you can see the alignment does not allow you to say this shot is fake. Listen my advice: take a walk/ride/drive towards Castagneto Po in a beautiful day and see for yourself :ssmile:
Visto che sei di Torino te lo spiego in italiano; io ho vissuto per anni in pieno centro con vista su Superga; decine di volte ho visto la Luna sorgere da dietro la Basilica, la luna come si sa ha estensione di circa 30' ed è più piccola della Basilica, entrambi questi oggetti sono 'fermi', cioè a uguale distanza sempre. Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Since you're from Turin, I'll explain it to you in Italian; I lived for years in the center with a view of Superga; dozens of times I have seen the Moon rise from behind the Basilica, the moon as we know has an extension of about 30' and is smaller than the Basilica, both of these objects are 'stationary', that is, always at the same distance. No lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.
The Moon and the basilica each subtend about a half degree, which is consistent with the camera being 82 km from the peak and 11 km from the basilica. Which would make everything in focus with any ordinary camera lens, and give exactly the geometry we see here. Nothing is "magnified", a term that doesn't even have any meaning in this context.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Sat Dec 30, 2023 3:28 pm

Liviux wrote: Sat Dec 30, 2023 10:32 am I don't know the area much, but I think the photo was taken somewhere near Castiglione Torinese:
Image
As you can see, not only the distance to Monviso is over 70 km, but the line of sight is above Turin. The city lights are probably contributing to the sky color much more than the twilight.
I'd put it further away. The basilica and the Moon subtend about the same angle, and the basilica width is about 100 meters. That would place the photographer about 11km from the basilica, which looks to be near a small village, Raccone.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by eaglekepr » Sat Dec 30, 2023 11:47 am

The photographer states he used a telephoto 500mm lens and has also posted a video clip on his Facebook post showing the camera as it was taking the image. It all appears consistent with the photo.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by nikkam » Sat Dec 30, 2023 11:00 am

EmanueleBalboni wrote: Fri Dec 29, 2023 4:03 pm
nikkam wrote: Thu Dec 28, 2023 6:29 am I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.
I also live in Turin, and not knowing the place from which you can see the alignment does not allow you to say this shot is fake. Listen my advice: take a walk/ride/drive towards Castagneto Po in a beautiful day and see for yourself :ssmile:
Visto che sei di Torino te lo spiego in italiano; io ho vissuto per anni in pieno centro con vista su Superga; decine di volte ho visto la Luna sorgere da dietro la Basilica, la luna come si sa ha estensione di circa 30' ed è più piccola della Basilica, entrambi questi oggetti sono 'fermi', cioè a uguale distanza sempre. Nessun obiettivo al mondo può mettere a fuoco contemporneamente la Basilica, a pochi km di distanza, il Monviso (3600 mt, ingrandito almeno 10x) che si trova a 64 km. da Torino, e luna ingrandita almeno 10x che si trova a 370.000 km di distanza. E' un fotomontaggio persino ridicolo a cui può credere solo chi non conosce il Piemonte, o non conosce la fotografia, o non conosce la geometria.
Since you're from Turin, I'll explain it to you in Italian; I lived for years in the center with a view of Superga; dozens of times I have seen the Moon rise from behind the Basilica, the moon as we know has an extension of about 30' and is smaller than the Basilica, both of these objects are 'stationary', that is, always at the same distance. No lens in the world can simultaneously focus on the Basilica, a few km away, and Monviso (3600 m, enlarged at least 10x) which is 64 km away. from Turin, and the moon magnified at least 10x which is 370,000 km away. It's an even ridiculous photomontage that only those who don't know Piedmont or don't know photography or don't know geometry can believe.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Liviux » Sat Dec 30, 2023 10:34 am

That said, I want to add my congratulations to Giacomo Venturini for this exceptional and much evocative picture.
Bravissimo!

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Liviux » Sat Dec 30, 2023 10:32 am

I don't know the area much, but I think the photo was taken somewhere near Castiglione Torinese:
Image
As you can see, not only the distance to Monviso is over 70 km, but the line of sight is above Turin. The city lights are probably contributing to the sky color much more than the twilight.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Fri Dec 29, 2023 4:22 pm

EmanueleBalboni wrote: Fri Dec 29, 2023 4:03 pm
nikkam wrote: Thu Dec 28, 2023 6:29 am I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.
I also live in Turin, and not knowing the place from which you can see the alignment does not allow you to say this shot is fake. Listen my advice: take a walk/ride/drive towards Castagneto Po in a beautiful day and see for yourself :ssmile:
There are dozens of images online that show exactly this perspective, with just the Moon missing. This is clearly a "standard tourist shot" of the basilica!

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by EmanueleBalboni » Fri Dec 29, 2023 4:03 pm

nikkam wrote: Thu Dec 28, 2023 6:29 am I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.
I also live in Turin, and not knowing the place from which you can see the alignment does not allow you to say this shot is fake. Listen my advice: take a walk/ride/drive towards Castagneto Po in a beautiful day and see for yourself :ssmile:

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by alter-ego » Fri Dec 29, 2023 3:26 am

nikkam wrote: Thu Dec 28, 2023 6:29 am I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.
So why do you think that?

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by nikkam » Thu Dec 28, 2023 6:29 am

I live in Turin (Torino) where Superga's Basilica is; only one who does not live in Turin can be supposed to think that this shot is true; it's only a tremendous fake.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by MarkBour » Thu Dec 28, 2023 2:26 am

FLPhotoCatcher wrote: Mon Dec 25, 2023 5:18 am Wow, great photo!
I agree, what an amazing image! It would not have been as great had Valerio Minato simply "happened" onto it. But to have planned it and had to return many times until this perfect capture, is so impressive and satisfying.

I think the light that is the Earthshine that lights the bulk of the Moon's disk here is different than the Earthshine one sees during a lunar eclipse. The latter, I believe, is from rays of sunlight that pass through Earth's atmosphere and -- slightly refracted -- head more directly to the surface of the Moon and then back to our eyes and cameras. The former, however, which we see in this image, first hits the Earth, mostly on places that are still in daylight, then reflects to the Moon, and finally bounces off its surface back to our eyes and cameras. This latter Earthshine, therefore, is a little bit different. It arrives at the Moon's surface about 1.3 seconds later* than the light that is directly illuminating the bright crescent. Not a big difference between the two kinds of Earthshine, just reflected rather than refracted on the journey.

I suppose some photon might have hit the Earth, reflected to the Moon, reflected to the backside of Monviso, reflected back to the Moon, and finally reflected back into the camera lens. At least a large number of photons made the first 3 legs of this journey, which is the whole reason you can see the silhouette of the mountain.

* (By "later", I'm just referring to photons that left the Sun at the same instant.)

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by VictorBorun » Tue Dec 26, 2023 9:36 am

Chris Peterson wrote: Mon Dec 25, 2023 10:13 pm
VictorBorun wrote: Mon Dec 25, 2023 10:01 pm
Chris Peterson wrote: Mon Dec 25, 2023 9:54 pm
I'm assuming that the imager's stated time of 18:52 is his local time, CST (or 17:52 UT), which is what I'm basing my calculation on.

FWIW, the mountain is 70 km from the basilica, and about 3000 m higher. So there's no way at all the Moon could be 9° above the horizon.
3 km / 70 km = tg 2.5°
ok, the hour is set and night it is.
Where are the stars?
Why the blue shine is of the same brightness in front of and beside the mountain? (Except close to the crescent, where the orange shine prevails)

Image
It does not surprise me that the sky is the same everywhere. Certainly, under all but the most clear of conditions, most of the scatter will be within that 70 km slice between the basilica and the mountain. In the day, the mountain might barely be visible, all but lost in atmospheric scatter.

There may be a couple of stars visible just above the Moon. I can't match them reliably to anything on my charts, though. Or rather, I can, but if they were those objects, we ought to see other brighter ones also. So I'm not sure what's going on with the blue sky and absence of stars. Again, we really need more detail on how the image was made and processed.
I am trying to guess the 2 stars like this.
1) switch off the atmosphere in Stellarium
2) subtract the blue shine and stretch this APOD till the disk of Moon is round to roughly correct the atmosphere lensing
3) fit a screenshot of Stellarium page to the stretched APOD

Voila, there are two brightest stars in right places!

The bright orange one at right is BD Capricorni, Magnitude=7.53, Spectral Type = A9III
The blinking one at left is HD 191501, Magnitude=9.13, Spectral Type=A2
Cathedral, Mountain, Moon fitting.jpg
Cathedral, Mountain, Moon fitting 2.jpg
...
Click to view full size image 1 or image 2

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by VictorBorun » Mon Dec 25, 2023 11:13 pm

Chris Peterson wrote: Mon Dec 25, 2023 11:04 pm
VictorBorun wrote: Mon Dec 25, 2023 11:00 pm after subtracting the blue shine (rgb = 45 64 91) there are some stars in the sky, probably not visible without a telescope
Cathedral, Mountain, Moon-black.jpg
I think the near total absence of stars is largely explained because we are looking through hundreds of kilometers of atmosphere within just a few degrees of the horizon. And maybe not the clearest atmosphere, at that.
70 km up to Monteviso is much clearer than say 350 km behind it to judge from the sharp mountain's edge versus Moon's blurred features

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Mon Dec 25, 2023 11:04 pm

VictorBorun wrote: Mon Dec 25, 2023 11:00 pm after subtracting the blue shine (rgb = 45 64 91) there are some stars in the sky, probably not visible without a telescope
Cathedral, Mountain, Moon-black.jpg
I think the near total absence of stars is largely explained because we are looking through hundreds of kilometers of atmosphere within just a few degrees of the horizon. And maybe not the clearest atmosphere, at that.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by VictorBorun » Mon Dec 25, 2023 11:00 pm

after subtracting the blue shine (rgb = 45 64 91) there are some stars in the sky, probably not visible without a telescope
Cathedral, Mountain, Moon-black.jpg

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Mon Dec 25, 2023 10:13 pm

VictorBorun wrote: Mon Dec 25, 2023 10:01 pm
Chris Peterson wrote: Mon Dec 25, 2023 9:54 pm
VictorBorun wrote: Mon Dec 25, 2023 8:29 pm

I am feeling lost. Is Stellarium so unprecise? Is using "local time" half an hour off the time zone?
I'm assuming that the imager's stated time of 18:52 is his local time, CST (or 17:52 UT), which is what I'm basing my calculation on.

FWIW, the mountain is 70 km from the basilica, and about 3000 m higher. So there's no way at all the Moon could be 9° above the horizon.
3 km / 70 km = tg 2.5°
ok, the hour is set and night it is.
Where are the stars?
Why the blue shine is of the same brightness in front of and beside the mountain? (Except close to the crescent, where the orange shine prevails)

Image
It does not surprise me that the sky is the same everywhere. Certainly, under all but the most clear of conditions, most of the scatter will be within that 70 km slice between the basilica and the mountain. In the day, the mountain might barely be visible, all but lost in atmospheric scatter.

There may be a couple of stars visible just above the Moon. I can't match them reliably to anything on my charts, though. Or rather, I can, but if they were those objects, we ought to see other brighter ones also. So I'm not sure what's going on with the blue sky and absence of stars. Again, we really need more detail on how the image was made and processed.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by VictorBorun » Mon Dec 25, 2023 10:01 pm

Chris Peterson wrote: Mon Dec 25, 2023 9:54 pm
VictorBorun wrote: Mon Dec 25, 2023 8:29 pm
Chris Peterson wrote: Mon Dec 25, 2023 8:21 pm
Double checked the ephemeris. Taking the location as Turin (because it's in the list, and only a few miles away), 15 Dec 2023, 18:52 local, I get the Moon at 2° above the horizon, the Sun at 21° below the horizon, Moon at 10% waxing.
I am feeling lost. Is Stellarium so unprecise? Is using "local time" half an hour off the time zone?
I'm assuming that the imager's stated time of 18:52 is his local time, CST (or 17:52 UT), which is what I'm basing my calculation on.

FWIW, the mountain is 70 km from the basilica, and about 3000 m higher. So there's no way at all the Moon could be 9° above the horizon.
3 km / 70 km = tg 2.5°
ok, the hour is set and night it is.
Where are the stars?
Why the blue shine is of the same brightness in front of and beside the mountain? (Except close to the crescent, where the orange shine prevails)

Image

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by Chris Peterson » Mon Dec 25, 2023 9:54 pm

VictorBorun wrote: Mon Dec 25, 2023 8:29 pm
Chris Peterson wrote: Mon Dec 25, 2023 8:21 pm
VictorBorun wrote: Mon Dec 25, 2023 5:38 pm
out of astronomical twilight? And where are the stars?

Moon's disk does look like illuminated by 10% of diameter along the axis of the crescent's symmetry and the axis is tilted by 30°
cos 37°= 0.8, so an angular distance of 37°seems probable between Sun's and Moon's disks
The 30° tilt makes the vertical angular distance 37°/2 = 18.5°
If Moon's disk is 2° above the horizon, then Sun's must be 16.5° below, mustn't it?
MoonAligned_Minato_2974-5.jpg
Double checked the ephemeris. Taking the location as Turin (because it's in the list, and only a few miles away), 15 Dec 2023, 18:52 local, I get the Moon at 2° above the horizon, the Sun at 21° below the horizon, Moon at 10% waxing.
I am feeling lost. Is Stellarium so unprecise? Is using "local time" half an hour off the time zone?
I'm assuming that the imager's stated time of 18:52 is his local time, CST (or 17:52 UT), which is what I'm basing my calculation on.

FWIW, the mountain is 70 km from the basilica, and about 3000 m higher. So there's no way at all the Moon could be 9° above the horizon.

Re: APOD: Cathedral, Mountain, Moon (2023 Dec 25)

by VictorBorun » Mon Dec 25, 2023 9:18 pm

Chris Peterson wrote: Mon Dec 25, 2023 8:21 pm
VictorBorun wrote: Mon Dec 25, 2023 5:38 pm
Chris Peterson wrote: Mon Dec 25, 2023 4:40 pm

This is a 10% Moon that is 2° above the horizon. The Sun is 21° below the horizon, so just out of astronomical twilight and it should not be contributing significant light.

I would be curious to know the technical details of the image. I don't think it could be achieved without some kind of HDR processing, so it's hard to assess the actual relative brightnesses of different parts.
out of astronomical twilight? And where are the stars?

Moon's disk does look like illuminated by 10% of diameter along the axis of the crescent's symmetry and the axis is tilted by 30°
cos 37°= 0.8, so an angular distance of 37°seems probable between Sun's and Moon's disks
The 30° tilt makes the vertical angular distance 37°/2 = 18.5°
If Moon's disk is 2° above the horizon, then Sun's must be 16.5° below, mustn't it?
MoonAligned_Minato_2974-5.jpg
Double checked the ephemeris. Taking the location as Turin (because it's in the list, and only a few miles away), 15 Dec 2023, 18:52 local, I get the Moon at 2° above the horizon, the Sun at 21° below the horizon, Moon at 10% waxing.
it's the time difference of 1 hour: 20:52
Cathedral, Mountain, Moon+1h.jpg
Moon's Altitude = +02°17'18.4", Phase = 10%
Sun's Altitude = -21°01'18.9"

Вut which hour it was in fact, twilight or night?

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