APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Comments and questions about the APOD on the main view screen.
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APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby APOD Robot » Tue Jul 03, 2012 4:11 am

Image In the Shadow of Saturns Rings

Explanation: Humanity's robot orbiting Saturn has recorded yet another amazing view. That robot, of course, is the spacecraft Cassini, while the new amazing view includes a bright moon, thin rings, oddly broken clouds, and warped shadows. Titan, Saturn's largest moon, appears above as a featureless tan as it is continually shrouded in thick clouds. The rings of Saturn are seen as a thin line because they are so flat and imaged nearly edge on. Details of Saturn's rings are therefore best visible in the dark ring shadows seen across the giant planet's cloud tops. Since the ring particles orbit in the same plane as Titan, they appear to skewer the foreground moon. In the upper hemisphere of Saturn, the clouds show many details, including dips in long bright bands indicating disturbances in a high altitude jet stream. Recent precise measurements of how much Titan flexes as it orbits Saturn hint that vast oceans of water might exist deep underground.

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Beyond » Tue Jul 03, 2012 4:42 am

It's always amazing just how messy ring particules can be. :puppy: :yes:

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby bystander » Tue Jul 03, 2012 4:51 am

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Mactavish » Tue Jul 03, 2012 5:24 am

Another superb image returned by Cassini over the past eight years. What an accomplishment! If only Cassini himself and Galileo, too, could be here today to view what we are able to enjoy.

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Markus Schwarz » Tue Jul 03, 2012 7:52 am

Can someone please guide my eye and tell me where the bright moon (Epimetheus?) can be found in the picture? Thanks!

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby neufer » Tue Jul 03, 2012 10:46 am

Markus Schwarz wrote:
Can someone please guide my eye and tell me where the bright moon (Epimetheus?) can be found in the picture? Thanks!

The bright (i.e., large) moon is Titan.
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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby orin stepanek » Tue Jul 03, 2012 11:45 am

Interesting moon indeed! Imagine oceans of methane on the surface and oceans of water underneath!!! :roll: :)
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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Markus Schwarz » Tue Jul 03, 2012 11:56 am

neufer wrote:The bright (i.e., large) moon is Titan.


Thank you! But wouldn't an adjective like 'prominent' or 'picturesque' be more appropriate? English is not my native language, and 'bright' is confusing to me in this context, where the moon in question is actually brown/dark in the picture.

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby neufer » Tue Jul 03, 2012 12:16 pm

Markus Schwarz wrote:
neufer wrote:
The bright (i.e., large) moon is Titan.

Thank you! But wouldn't an adjective like 'prominent' or 'picturesque' be more appropriate? English is not my native language, and 'bright' is confusing to me in this context, where the moon in question is actually brown/dark in the picture.

A link such as: http://apod.nasa.gov/apod/ap120414.html would certainly have been more appropriate.

(But Otto Posterman is none too bright sometimes :wink: .)
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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby owlice » Tue Jul 03, 2012 12:19 pm

neufer wrote:(But Otto Posterman is none too bright sometimes :wink: .)

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Keyman » Tue Jul 03, 2012 1:42 pm

Hey guys...Welcome back. Glad you got the power back.

Owlice... Have you trademarked that signature, and if so where can I send the royalties when I steal it?

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Re: APOD: In the Shadow of Saturn's Rings (2012 Jul 03)

Postby LocalColor » Tue Jul 03, 2012 3:07 pm

Glad to see APOD back on its regular place. Wonderful photo today!

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby LEK » Tue Jul 03, 2012 3:08 pm

Is it my monitor only, or does this image seem to out of register? I'm seeing a blue fringe on many of the objects.

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Keyman » Tue Jul 03, 2012 3:27 pm

Markus Schwarz wrote:Can someone please guide my eye and tell me where the bright moon (Epimetheus?) can be found in the picture? Thanks!

There is a prior APOD that includes Epimetheus.
http://apod.nasa.gov/apod/ap090505.html

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Chris Peterson » Tue Jul 03, 2012 3:37 pm

LEK wrote:Is it my monitor only, or does this image seem to out of register? I'm seeing a blue fringe on many of the objects.

Cassini's cameras can only image through one filter at a time, so color images are composites with a time lag between frames. Because the spacecraft is moving, the field of view is also changing with time. This is partially compensated for by changing the orientation of the camera between frames, and also by various image processing tricks during post processing on the ground. But the corrections are only partial, so most Cassini images have some degree of misregistration between color channels. It's usually only apparent at high contrast edges.
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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby WallyBalls » Tue Jul 03, 2012 3:52 pm

So, is the blue fringe along the lower left edge of Saturn an optical system aberration or is that the outer atmosphere?

Wallyballs

Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Wallyballs » Tue Jul 03, 2012 4:05 pm

WallyBalls wrote:So, is the blue fringe along the lower left edge of Saturn an optical system aberration or is that the outer atmosphere?

Oops - just saw the explanation in the post that preceded mine....

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Hari Gaurav » Tue Jul 03, 2012 5:02 pm

:D One of the best from Cassini

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby neufer » Tue Jul 03, 2012 5:44 pm

Chris Peterson wrote:
LEK wrote:
Is it my monitor only, or does this image seem to out of register? I'm seeing a blue fringe on many of the objects.

Cassini's cameras can only image through one filter at a time, so color images are composites with a time lag between frames. Because the spacecraft is moving, the field of view is also changing with time. This is partially compensated for by changing the orientation of the camera between frames, and also by various image processing tricks during post processing on the ground. But the corrections are only partial, so most Cassini images have some degree of misregistration between color channels. It's usually only apparent at high contrast edges.

One can't properly compensate for both Saturn and the foreground Titan.

However, red/blue 3D glasses worn backwards (red to right eye) gives something of a 3D effect.
Art Neuendorffer

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Chris Peterson » Tue Jul 03, 2012 5:55 pm

neufer wrote:One can't properly compensate for both Saturn and the foreground Titan.

One can't easily compensate for anything... adding a near and far object just complicates things, of course.

There are fully compensated images, however. They are made by mapping each pixel to a coordinate on the body (or bodies) and then mapping the intensity values onto virtual surfaces and rerendering the image. This provides the highest resolution multiband imagery, but is far too complex to apply to more than a fraction of the hundreds of thousands of images that have been returned. The method is increasingly common with Mars orbital imagery as well as Earth orbital imagery.
Chris

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Moonlady » Tue Jul 03, 2012 6:27 pm

Wow, Saturn got a Titan- pearl on it's chain!

Ian Regan

Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Ian Regan » Tue Jul 03, 2012 10:59 pm

This image was also processed by Gordan Ugarkovic over at the UMSF forums:

http://www.unmannedspaceflight.com/inde ... ntry184238
http://www.unmannedspaceflight.com/inde ... ntry184237

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby saturno2 » Wed Jul 04, 2012 12:37 am

Saturn, my favorite planet.
This image could be called transit of Titan before Saturn.
Titan has water. It¨s very interesting

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby owlice » Wed Jul 04, 2012 12:59 am

Keyman wrote:Owlice... Have you trademarked that signature, and if so where can I send the royalties when I steal it?

Keyman, I'm kind of sorry to have to tell you it's not original; here ya go.

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Re: APOD: In the Shadow of Saturns Rings (2012 Jul 03)

Postby Ann » Wed Jul 04, 2012 8:11 pm

This is a very beautiful image. Saturn looks splendid. I like the subtle cloud patterns; are these seen in optical light? I like (obviously) the hint of blue in Saturn's southern(?) hemisphere.

I find the contrast between Saturn's light-colored brilliance and Titan's relative darkness interesting. Saturn is not being saturnine here, but Titan is, I think!

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