APOD: In the Shadow of Saturn (2011 Sep 04)

Comments and questions about the APOD on the main view screen.
RickM

Orange smudges

Post by RickM » Thu Sep 08, 2011 3:14 pm

Fascinating image.

One feature I don't see discussed is the orange smudges below, and fainter ones above, Saturn and the rings. Are those part of the solar corona?

William Boyd

Re: APOD: In the Shadow of Saturn (2011 Sep 04)

Post by William Boyd » Sat Sep 10, 2011 8:25 am

"What is man that thou art mindful of him?"

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Case
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Re: Orange smudges

Post by Case » Sat Sep 10, 2011 8:56 am

RickM wrote:One feature I don't see discussed is the orange smudges below, and fainter ones above, Saturn and the rings.
It's camera artifacts.
http://ciclops.org/view.php?id=2230&flash=1&js=1
“The main rings are overexposed in a few places. Reddish lens flares are visible in both versions of the view. These radially extending artifacts result from light being scattered within the camera optics.”
I, for one, like Roman numerals.

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neufer
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Re: Orange smudges

Post by neufer » Sat Sep 10, 2011 9:32 am

Case wrote:
RickM wrote:
One feature I don't see discussed is the orange smudges below, and fainter ones above, Saturn and the rings.
It's camera artifacts. http://ciclops.org/view.php?id=2230&flash=1&js=1

“The main rings are overexposed in a few places. Reddish lens flares are visible in both versions of the view. These radially extending artifacts result from light being scattered within the camera optics.”
<<Schmutz (Shmoots): a Yiddish word for dirt, or mud or some such stuff.

If you just ate a cream doughnut you might have some schmutz on your shirt where the cream fell out.>>
Art Neuendorffer

sjohnsonart

Re: APOD: In the Shadow of Saturn (2011 Sep 04)

Post by sjohnsonart » Tue Sep 20, 2011 10:46 pm

This is my most favorite image you have ever distributed through the internet! I am a visual artist, and I think the form and color of this image is colossal. I measure my time in the cosmos by Saturn, being now in my third orbit. Thank you for this gift! sally j :clap:

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Old (but classic) Saturn pic - please explain!

Post by gmPhil » Fri Sep 30, 2011 8:26 am

Re this image of Saturn: http://apod.nasa.gov/apod/ap090111.html - one of my favourites - can somoene please explain why or how it is that the outer foreground rings appear to go behind the planet? (Just above where you can see the sun peeking out...) This has long bothered me...
Thanks...

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Ann
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Re: Old (but classic) Saturn pic - please explain!

Post by Ann » Fri Sep 30, 2011 8:58 am

I'm not the best person to talk about this, gmPhil. I'll talk at length about blue stars and starforming galaxies, but about Saturn... not so much.

Still, let's look at the picture again. You can see that there are some strange "ring shapes" on the "disk" or "body" of Saturn itself. However, what we see here is mostly the shadows of the rings, not so much the rings themselves.
Image
Here you can see a man's feet and lower legs and the shadows of his feet and lower legs. They are not in the same plane. You could photograph the man so that you see little of his shadow, and you could photograph the shadow so that you see little of the man.

I think we see both the dark unlit rings across the very faintly lit "disk" of Saturn, but we also see the shadows of the rings on the "disk" of Saturn. However, the rings also seem to be "backlighting" Saturn, faintly reflecting the sunlight they receive on the dark night side of Saturn.

I think it is this complex "shadow play" with dark shadows as well as reflected light that makes the rings appear to be "broken" over Saturn. Note that the rings are "tilted" from our point of view, further complicating the "shadow play".

Why is the outer "rim" of Saturn so bright? I would guess that it has to do with the mist above the cloudtops of Saturn. Jupiter doesn't have this kind of mist, which is why the cloud features of Jupiter are so stark and dramatic. The cloud tops of Saturn are so much more muted, because they are covered by mist. I would guess that this mist acts as a reflection nebula, spreading the light of the Sun around the circumference of the planet. But the mist is almost certainly semi-transparent, which is why you can see the Sun peeking through.

I also think that the shadow of Saturn itself is falling on the brightly lit rings, so that the rings seem to "disappear" before they "reach" the disk of Saturn.

I have no idea if I answered your question, gmPhil, but if not, why don't you ask, say, Chris or Art?

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Re: APOD: In the Shadow of Saturn (2011 Sep 04)

Post by gmPhil » Fri Sep 30, 2011 9:19 am

Well, thanks Ann - I understand there may be all kinds of light-illusions going on, nevertheless I stil find it hard to understand what makes those lower foreground rings "disappear" like they do! Mind you, I dare say there's a lot of things I fail to understand! :)