APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

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APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by APOD Robot » Wed Apr 26, 2023 4:05 am

Image The Moon through the Arc de Triomphe

Explanation: Was this a lucky shot? Although many amazing photographs are taken by someone who just happened to be in the right place at the right time, this image took skill and careful planning. First was the angular scale: if you shoot too close to the famous Arc de Triomphe in Paris, France, the full moon will appear too small.  Conversely, if you shoot from too far away, the moon will appear  too large and not fit inside the Arc. Second is timing: the Moon only appears centered inside the Arc for small periods of time -- from this distance less than a minute. Other planned features include lighting, relative brightness, height, capturing a good foreground, and digital processing. And yes, there is some luck involved -- for example, the sky must be clear. This time, the planning was successful, bringing two of humanity's most famous icons photographically together for all to enjoy.

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by alex555 » Wed Apr 26, 2023 7:33 am

And by the way, a salute to our valiant French friends who are fighting so hard for their unique pension system in the world, and that neo-liberal pension funds are trying to steal from them.

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 1:05 pm

Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by sp0ck » Wed Apr 26, 2023 1:22 pm

someone should tell the guy standing on top of the arc and looking down that he's missing a view of a really beautiful moon...

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Chris Peterson » Wed Apr 26, 2023 1:23 pm

johnnydeep wrote: Wed Apr 26, 2023 1:05 pm Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?
I don't see why not. There are no obvious geometric limitations on where in the sky the Sun can be eclipsed. Whether such an alignment will occur before the Moon and Sun are no longer the same angular size, however...
Chris

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Ann » Wed Apr 26, 2023 2:31 pm

johnnydeep wrote: Wed Apr 26, 2023 1:05 pm Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?

Unimpressed, Johnny? That moonshot is nothing special? :wink:

Well, that reminds me of an old Swedish sketch about two men arguing. We may call them Hasse and Tage, since that were their names. So Hasse asked Tage where he was going to spend his vacation.


"In Majorca", said Tage.

arubapng[1].png
Aruba.

"Majorca", scoffed Hasse, "that's so old and boring! No, Aruba, that's the place to be!"

"So where are you going to spend your vacation?" asked Tage.


"In Säffle", said Hasse. "Can I have a cup of coffee?"


So, Johnny. Today's APOD may not be as cool as an eclipsed Moon fitting perfectly inside the Arc de Triomphe, but I'll take this photo any day over Säffle! If you know what I mean.

Ann
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 2:33 pm

Chris Peterson wrote: Wed Apr 26, 2023 1:23 pm
johnnydeep wrote: Wed Apr 26, 2023 1:05 pm Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?
I don't see why not. There are no obvious geometric limitations on where in the sky the Sun can be eclipsed. Whether such an alignment will occur before the Moon and Sun are no longer the same angular size, however...
Hmm. So a solar eclipse can be seen from any spot on the surface of the Earth (at the appropriate time of course)?
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 2:42 pm

Ann wrote: Wed Apr 26, 2023 2:31 pm
johnnydeep wrote: Wed Apr 26, 2023 1:05 pm Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?
...

So, Johnny. Today's APOD may not be as cool as an eclipsed Moon fitting perfectly inside the Arc de Triomphe, but I'll take this photo any day over Säffle! If you know what I mean.

Ann
Sure, there are indeed grades of awesomeness, and that assessment often lies in the eye of the beholder. But I still think less likely things are more awesome than more likely things. My attempt at humor was to guess that an annular solar eclipse observed in the same setting would be more impressive due to its being - perhaps much - more rare. That said, as we sit here at our computers with easy access to all these nice photos, who are we to be critical?

[ PS - still not getting email notifications, only the internal notifications that I can view when I'm logged in. Plus, I'm getting logged out much more often than I used to be! ]
Last edited by johnnydeep on Wed Apr 26, 2023 2:44 pm, edited 1 time in total.
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Chris Peterson » Wed Apr 26, 2023 2:42 pm

johnnydeep wrote: Wed Apr 26, 2023 2:33 pm
Chris Peterson wrote: Wed Apr 26, 2023 1:23 pm
johnnydeep wrote: Wed Apr 26, 2023 1:05 pm Meh. :-) What would be truly impressive is seeing an annular solar eclipse centered under the Arc De Triomphe like that. But is that even geometrically possible?
I don't see why not. There are no obvious geometric limitations on where in the sky the Sun can be eclipsed. Whether such an alignment will occur before the Moon and Sun are no longer the same angular size, however...
Hmm. So a solar eclipse can be seen from any spot on the surface of the Earth (at the appropriate time of course)?
I think so.
Chris

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 2:48 pm

Chris Peterson wrote: Wed Apr 26, 2023 2:42 pm
johnnydeep wrote: Wed Apr 26, 2023 2:33 pm
Chris Peterson wrote: Wed Apr 26, 2023 1:23 pm

I don't see why not. There are no obvious geometric limitations on where in the sky the Sun can be eclipsed. Whether such an alignment will occur before the Moon and Sun are no longer the same angular size, however...
Hmm. So a solar eclipse can be seen from any spot on the surface of the Earth (at the appropriate time of course)?
I think so.
Interesting. I would have guessed that the close to co-planar orbits of the Earth and Moon, along with the particular tilt of the Earth's axis, would have prevented that. Now I have to wonder if there are any orbital configurations of a planet, moon and sun that would make eclipses visible only from certain places.


EDIT: well sure, if the moon orbited perpendicularly to the plane of the Earth's orbit, and the Earth's axial tilt was zero, there would be no solar eclipses to be see from anywhere! Wait - no that's not right either is it. The moon could still pass between the sun and Earth twice a year.
Last edited by johnnydeep on Wed Apr 26, 2023 3:29 pm, edited 3 times in total.
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Chris Peterson » Wed Apr 26, 2023 3:14 pm

johnnydeep wrote: Wed Apr 26, 2023 2:48 pm
Chris Peterson wrote: Wed Apr 26, 2023 2:42 pm
johnnydeep wrote: Wed Apr 26, 2023 2:33 pm

Hmm. So a solar eclipse can be seen from any spot on the surface of the Earth (at the appropriate time of course)?
I think so.
Interesting. I would have guessed that the close to co-planar orbits of the Earth and Moon, along with the particular tilt of the Earth's axis, would have prevented that. Now I have to wonder if there are any configurations of planet, moon and sun that would make eclipses visible only from certain places.

I can't think of any reason that an eclipse shouldn't be able to happen anywhere. There is a semi-periodicity to eclipses (Saros cycle) that might weigh the probability of certain places over others in any short term period (a few thousand years). But there are no true resonances in any of the orbital periods or angles involved, so at least over a long period, I think the probability of an eclipse is the same at any location. And at any location, you'll get a total eclipse about once every 380 years.
Chris

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 3:32 pm

Chris Peterson wrote: Wed Apr 26, 2023 3:14 pm
johnnydeep wrote: Wed Apr 26, 2023 2:48 pm
Chris Peterson wrote: Wed Apr 26, 2023 2:42 pm
I think so.
Interesting. I would have guessed that the close to co-planar orbits of the Earth and Moon, along with the particular tilt of the Earth's axis, would have prevented that. Now I have to wonder if there are any configurations of planet, moon and sun that would make eclipses visible only from certain places.

I can't think of any reason that an eclipse shouldn't be able to happen anywhere. There is a semi-periodicity to eclipses (Saros cycle) that might weigh the probability of certain places over others in any short term period (a few thousand years). But there are no true resonances in any of the orbital periods or angles involved, so at least over a long period, I think the probability of an eclipse is the same at any location. And at any location, you'll get a total eclipse about once every 380 years.
Would that apply to ANY orbital configuration (except for the 380 year time period perhaps)?
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Chris Peterson » Wed Apr 26, 2023 3:34 pm

johnnydeep wrote: Wed Apr 26, 2023 3:32 pm
Chris Peterson wrote: Wed Apr 26, 2023 3:14 pm
johnnydeep wrote: Wed Apr 26, 2023 2:48 pm

Interesting. I would have guessed that the close to co-planar orbits of the Earth and Moon, along with the particular tilt of the Earth's axis, would have prevented that. Now I have to wonder if there are any configurations of planet, moon and sun that would make eclipses visible only from certain places.

I can't think of any reason that an eclipse shouldn't be able to happen anywhere. There is a semi-periodicity to eclipses (Saros cycle) that might weigh the probability of certain places over others in any short term period (a few thousand years). But there are no true resonances in any of the orbital periods or angles involved, so at least over a long period, I think the probability of an eclipse is the same at any location. And at any location, you'll get a total eclipse about once every 380 years.
Would that apply to ANY orbital configuration (except for the 380 year time period perhaps)?
Any orbital configuration?
Chris

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by orin stepanek » Wed Apr 26, 2023 5:47 pm

MoonArc_zanarello_960.jpg
OMG! What a shot! I love it!
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Wed Apr 26, 2023 8:13 pm

Chris Peterson wrote: Wed Apr 26, 2023 3:34 pm
johnnydeep wrote: Wed Apr 26, 2023 3:32 pm
Chris Peterson wrote: Wed Apr 26, 2023 3:14 pm

I can't think of any reason that an eclipse shouldn't be able to happen anywhere. There is a semi-periodicity to eclipses (Saros cycle) that might weigh the probability of certain places over others in any short term period (a few thousand years). But there are no true resonances in any of the orbital periods or angles involved, so at least over a long period, I think the probability of an eclipse is the same at any location. And at any location, you'll get a total eclipse about once every 380 years.
Would that apply to ANY orbital configuration (except for the 380 year time period perhaps)?
Any orbital configuration?
Yes, but a stable one of course. A moon orbiting in an orbit much less coplanar with the orbit of the planet, and/or a different axial tilt of the planet.
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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by Chris Peterson » Wed Apr 26, 2023 8:24 pm

johnnydeep wrote: Wed Apr 26, 2023 8:13 pm
Chris Peterson wrote: Wed Apr 26, 2023 3:34 pm
johnnydeep wrote: Wed Apr 26, 2023 3:32 pm

Would that apply to ANY orbital configuration (except for the 380 year time period perhaps)?
Any orbital configuration?
Yes, but a stable one of course. A moon orbiting in an orbit much less coplanar with the orbit of the planet, and/or a different axial tilt of the planet.
Well, I'm sure you could construct an orbit that limited eclipse possibilities.
Chris

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by American Citizen » Wed Apr 26, 2023 11:07 pm

I will be pilloried for this reply, but the moon is not quite located in the center of the arch of the Arc de Triomphe. Using gimp, I was able to use the elliptical cut option and move the moon image upwards a few pixels to the NNW or 2 o'clock position and discovered that the moon is not quite full yet, there is some surface still not illuminated in the upper portion, so the picture wasn't taken at the full moon moment, but just a bit afterwards? I would tell the camera person to find a slightly higher position, the next time this shot is taken.

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Re: APOD: The Moon through the Arc de Triomphe (2023 Apr 26)

Post by johnnydeep » Thu Apr 27, 2023 1:43 pm

American Citizen wrote: Wed Apr 26, 2023 11:07 pm I will be pilloried for this reply, but the moon is not quite located in the center of the arch of the Arc de Triomphe. Using gimp, I was able to use the elliptical cut option and move the moon image upwards a few pixels to the NNW or 2 o'clock position and discovered that the moon is not quite full yet, there is some surface still not illuminated in the upper portion, so the picture wasn't taken at the full moon moment, but just a bit afterwards? I would tell the camera person to find a slightly higher position, the next time this shot is taken.
Vive la France! Et vive la lune!
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