APOD: A Plutonian Landscape (2021 Jan 15)

Comments and questions about the APOD on the main view screen.
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johnnydeep
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by johnnydeep » Sat Jan 16, 2021 4:56 pm

Chris Peterson wrote:
Sat Jan 16, 2021 3:16 pm
johnnydeep wrote:
Sat Jan 16, 2021 3:10 pm
Cousin Ricky wrote:
Sat Jan 16, 2021 3:57 am


Ever look at black asphalt in bright sunlight immediately after walking out of a dark building?

At nighttime, the Moon (and planets, if any) are the only objects in direct sunlight, while your eyes are adjusted to seeing things in the dark.

During the daytime, the Moon looks a little brighter than asphalt, because only the lighter lunar highlands are visible through the atmosphere.
Oh boy, I'm still finding this "the moon is a dark as asphalt" fact very hard to fathom, now even more so after you mentioning the moon in daytime. Here's a typical(?) picture of how I remember the moon appearing in daylight, in a blue sky:
The light areas on the moon sure look lighter than what I would think asphalt would look like in the moon's place. The dark areas look about the same as the blue sky, but sill brighter than asphalt. I suppose it must be a type of optical illusion.
You need to be very cautious comparing a photograph to what your eye sees. Again, photos are normalized to span the range from black to white, i.e. from the minimum to the maximum value that a pixel can have. Your eyes/brain dynamically process a very wide dynamic range and build a perceptual image that is not accurately representative of actual intensities.
Ok, point taken, but wouldn't this photo, assuming no special processing, still be accurately representing the relative brightnesses of the objects in it?

I'd like to see the moon in daylight right behind an asphalt-black mountain. Though the mountain in the pic I posted has areas that look close, and, if anything, look lighter than asphalt, yet they still clearly appear to be darker than the moon.
"To Boldly Go......Beyond The Fields We Know."

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Chris Peterson
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Chris Peterson » Sat Jan 16, 2021 5:02 pm

johnnydeep wrote:
Sat Jan 16, 2021 4:56 pm
Chris Peterson wrote:
Sat Jan 16, 2021 3:16 pm
johnnydeep wrote:
Sat Jan 16, 2021 3:10 pm


Oh boy, I'm still finding this "the moon is a dark as asphalt" fact very hard to fathom, now even more so after you mentioning the moon in daytime. Here's a typical(?) picture of how I remember the moon appearing in daylight, in a blue sky:
The light areas on the moon sure look lighter than what I would think asphalt would look like in the moon's place. The dark areas look about the same as the blue sky, but sill brighter than asphalt. I suppose it must be a type of optical illusion.
You need to be very cautious comparing a photograph to what your eye sees. Again, photos are normalized to span the range from black to white, i.e. from the minimum to the maximum value that a pixel can have. Your eyes/brain dynamically process a very wide dynamic range and build a perceptual image that is not accurately representative of actual intensities.
Ok, point taken, but wouldn't this photo, assuming no special processing, still be accurately representing the relative brightnesses of the objects in it?

I'd like to see the moon in daylight right behind an asphalt-black mountain. Though the mountain in the pic I posted has areas that look close, and, if anything, look lighter than asphalt, yet they still clearly appear to be darker than the moon.
Not necessarily. From the camera all the way to your display, imaging systems implement non-linearizing steps (like gamma). And our eyes are also non-linear. You can't even see the dark areas of the Moon in the image you posted. They aren't returning enough photons to rise above the level of the sky background. That is, what you're calling the dark areas of the Moon are just the sky. If the entire Moon were that color, we wouldn't see it at all in bright daylight.
Chris

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johnnydeep
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by johnnydeep » Sat Jan 16, 2021 8:24 pm

Chris Peterson wrote:
Sat Jan 16, 2021 5:02 pm
johnnydeep wrote:
Sat Jan 16, 2021 4:56 pm
Chris Peterson wrote:
Sat Jan 16, 2021 3:16 pm

You need to be very cautious comparing a photograph to what your eye sees. Again, photos are normalized to span the range from black to white, i.e. from the minimum to the maximum value that a pixel can have. Your eyes/brain dynamically process a very wide dynamic range and build a perceptual image that is not accurately representative of actual intensities.
Ok, point taken, but wouldn't this photo, assuming no special processing, still be accurately representing the relative brightnesses of the objects in it?

I'd like to see the moon in daylight right behind an asphalt-black mountain. Though the mountain in the pic I posted has areas that look close, and, if anything, look lighter than asphalt, yet they still clearly appear to be darker than the moon.
Not necessarily. From the camera all the way to your display, imaging systems implement non-linearizing steps (like gamma). And our eyes are also non-linear. You can't even see the dark areas of the Moon in the image you posted. They aren't returning enough photons to rise above the level of the sky background. That is, what you're calling the dark areas of the Moon are just the sky. If the entire Moon were that color, we wouldn't see it at all in bright daylight.
Ok, thanks. Mind still blown. I need to learn more about imaging!
"To Boldly Go......Beyond The Fields We Know."

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Cousin Ricky
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Cousin Ricky » Mon Jan 18, 2021 3:45 pm

johnnydeep wrote:
Sat Jan 16, 2021 3:10 pm
Oh boy, I'm still finding this "the moon is a dark as asphalt" fact very hard to fathom, now even more so after you mentioning the moon in daytime. Here's a typical(?) picture of how I remember the moon appearing in daylight, in a blue sky:
I get this message for your image:
Sorry, our service is currently not available in your region
If Chris could see it, I suspect it’s because Chris and the website are both in Colorado.
johnnydeep wrote:
Sat Jan 16, 2021 3:10 pm
The light areas on the moon sure look lighter than what I would think asphalt would look like in the moon's place. The dark areas look about the same as the blue sky, but sill brighter than asphalt. I suppose it must be a type of optical illusion.
Nothing outside the atmosphere can appear darker than it. As Chris noted, you are not seeing the color of the lunar maria; you are seeing the color of the sky. It’s the same effect that causes faraway earthbound mountains to fade in the distance.

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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by bystander » Mon Jan 18, 2021 3:48 pm

Cousin Ricky wrote:
Mon Jan 18, 2021 3:45 pm
I get this message for your image:
Sorry, our service is currently not available in your region
If Chris could see it, I suspect it’s because Chris and the website are both in Colorado.

I suspect the problem is on your end. I'm not in Colorado and I can see it.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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Cousin Ricky
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Cousin Ricky » Mon Jan 18, 2021 3:55 pm

bystander wrote:
Mon Jan 18, 2021 3:48 pm
Cousin Ricky wrote:
Mon Jan 18, 2021 3:45 pm
I get this message for your image:
Sorry, our service is currently not available in your region
If Chris could see it, I suspect it’s because Chris and the website are both in Colorado.

I suspect the problem is on your end. I'm not in Colorado and I can see it.
I suspect the problem is in those damn geographic censorship algorithms. I get this a lot in the Virgin Islands.

And it’s not on the part of the Virgin Islands; we have no Chinese-style Great Firewall. It is the providers that are refusing to recognize us.

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Chris Peterson
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Chris Peterson » Mon Jan 18, 2021 4:06 pm

Cousin Ricky wrote:
Mon Jan 18, 2021 3:55 pm
bystander wrote:
Mon Jan 18, 2021 3:48 pm
Cousin Ricky wrote:
Mon Jan 18, 2021 3:45 pm
I get this message for your image:


If Chris could see it, I suspect it’s because Chris and the website are both in Colorado.

I suspect the problem is on your end. I'm not in Colorado and I can see it.
I suspect the problem is in those damn geographic censorship algorithms. I get this a lot in the Virgin Islands.

And it’s not on the part of the Virgin Islands; we have no Chinese-style Great Firewall. It is the providers that are refusing to recognize us.
I'd suggest you subscribe to a VPN. It's only a few dollars a year, and it lets you connect to problematic sites from any of hundreds of different countries. I access restricted Canadian, UK, and other content all the time that way. Well worth the cost if you live in a place where foreign content is frequently blocked.
Chris

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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Mountainjim62 » Mon Jan 18, 2021 7:59 pm

Ever notice the that people who go out of there way to prove their intelligence to others eventually slip up and make their utter lack of it quite obvious?
neufer wrote:
Fri Jan 15, 2021 7:13 pm
Paving over the entire Moon was scheduled to be part of Trump's 2021 Infrastructure Week

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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Chris Peterson » Mon Jan 18, 2021 9:12 pm

Mountainjim62 wrote:
Mon Jan 18, 2021 7:59 pm
Ever notice the that people who go out of there way to prove their intelligence...
Hmmm.
Chris

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Cousin Ricky
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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by Cousin Ricky » Tue Jan 19, 2021 10:12 pm

Chris Peterson wrote:
Mon Jan 18, 2021 9:12 pm
Mountainjim62 wrote:
Mon Jan 18, 2021 7:59 pm
Ever notice the that people who go out of there way to prove their intelligence...
Hmmm.
Muphry’s law will not be mocked! —Skitt

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Re: APOD: A Plutonian Landscape (2021 Jan 15)

Post by neufer » Tue Jan 19, 2021 10:47 pm

Cousin Ricky wrote:
Tue Jan 19, 2021 10:12 pm
Chris Peterson wrote:
Mon Jan 18, 2021 9:12 pm
Mountainjim62 wrote:
Mon Jan 18, 2021 7:59 pm

Ever notice the that people who go out of there way to prove their intelligence...
Hmmm.
Muphry’s law will not be mocked! —Skitt
https://en.wikipedia.org/wiki/Muphry%27s_law wrote:
<<Muphry's law is an adage that states: "If you write anything criticizing editing or proofreading, there will be a fault of some kind in what you have written." The name is a deliberate misspelling of "Murphy's law".

Names for variations on the principle have also been coined, usually in the context of online communication, including:
  • Skitt's law: "Any post correcting an error in another post will contain at least one error itself."

    Umhoefer's or Umhöfer's rule: "Articles on writing are themselves badly written."

    Hartman's law of prescriptivist retaliation: "Any article or statement about correct grammar, punctuation, or spelling is bound to contain at least one eror [sic]."

    The iron law of nitpicking: "You are never more likely to make a grammatical error than when correcting someone else's grammar."

    McKean's law: "Any correction of the speech or writing of others will contain at least one grammatical, spelling, or typographical error."

    Bell's first law of Usenet: "Flames of spelling and/or grammar will have spelling and/or grammatical errors.">>
Art Neuendorffer