
Close Views Show Saturn's Rings in Unprecedented Detail - upen
http://www.jpl.nasa.gov/news/news.php?feature=6729
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autocorr
The high-resolution image of Daphnis is pretty astonishing [1]. You can see
the moon back-illuminating a thin silver lining around the crest of the
trailing density wave. I missed it just looking at the thumbnail picture!

Both of the moons imaged in the flyby, Daphnis and Pandora, are of interest
because they're examples of shepherd moons [2] that sculpt the surrounding
ring material. For example, the Cassini Division [3] is made by Mimas clearing
material at the 2-to-1 orbital resonance. Daphnis, along with Pan, also
happens to be the only shepherd moon orbiting within Saturn's main rings.

[1]
[http://photojournal.jpl.nasa.gov/catalog/PIA21056](http://photojournal.jpl.nasa.gov/catalog/PIA21056)
(click the "full resolution JPEG")

[2]
[https://en.wikipedia.org/wiki/Shepherd_moon](https://en.wikipedia.org/wiki/Shepherd_moon)

[3]
[https://en.wikipedia.org/wiki/Rings_of_Saturn#Cassini_Divisi...](https://en.wikipedia.org/wiki/Rings_of_Saturn#Cassini_Division)

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semaphoreP
I recently learned that some of the density waves in Saturn ( shown in the top
picture in the article) are due to pressure waves in the interior of Saturn
itself, so the rings can actually be used to study the composition of the
interior of Saturn. I thought that was pretty remarkable.

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devindotcom
In case you're wondering what the flecks are, apparently it's cosmic radiation
and waves hitting the sensor (you have only to read the description to find
out but not everyone does). At first I thought there were millions of little
features in the rings!

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codeddesign
Agreed. More information about the "propellers" and specks here:
[http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21059](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21059)

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averagewall
I somehow expected to see the individual objects that make them up. If you
were close enough, would that be visible? Or would they be so sparse - like
clouds - that they become invisible at short distances?

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autocorr
Unfortunately not, the largest individual objects are ~10 m in size and these
images have a spatial resolution of 550 m, so they can't be resolved (at least
in this orbit). The particles range between 1 cm to 10 m, but what's
interesting is that it's possible to measure these sizes without actually
directly imaging them. The sizes can be inferred from how much of different
radio transmissions get absorbed as they pass from Cassini, through the rings,
and then to a receiver station on Earth. The basic principle is that a 1 cm
wavelength radio transmission will get absorbed by all particles equal to or
larger than 1 cm in size. With transmissions at 1, 4, and 13 cm, rings with
different compositions can be distinguished.

This method of radio occultation can be used to make very accurate physical
models of the ring systems. See this comparison image [1], and this helpful
description of the method from NASA [2].

[1]
[https://upload.wikimedia.orgthru/wikipedia/commons/1/1f/Satu...](https://upload.wikimedia.orgthru/wikipedia/commons/1/1f/Saturn%27s_rings_in_visible_light_and_radio.jpg)

[2]
[http://photojournal.jpl.nasa.gov/catalog/PIA07872](http://photojournal.jpl.nasa.gov/catalog/PIA07872)

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davesque
Nothings puts me in my place faster than this. To think that these are real
images of a real thing.

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na85
It's so close, in the grand scheme of things, and yet so utterly beyond our
capabilities to get one of us there.

Rather humbling.

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typetypetype
These are amazing. I wish there was an overlay on the images to give a sense
of scale.

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DigitalJack
If the eiffel tower were floating in one of the rings in these images, it
possibly might darken one of the pixels. The image resolution granularity is
about 500 meters (with the tower being 300).

