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Science (november 25, 2005)
Guest_AlexBlackwell_*
post Nov 25 2005, 05:47 PM
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From the November 25, 2005, issue of Science:

Cassini Discovers a Kinematic Spiral Ring Around Saturn
S. Charnoz, et al.
Science 310, 1300-1304 (2005).
Abstract
Supporting Online Material

See also the accompanying Perspectives piece by Mark Showalter:

Saturn's Strangest Ring Becomes Curiouser and Curiouser
Mark R. Showalter
Science 310, 1287-1288 (2005).
Summary
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mars loon
post Nov 27 2005, 05:42 PM
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Many more details of this stunning finding are available at the CICLOPS Website

View an informative slide presentation under the headline:

"Cassini Discovers the F Ring Is Embraced by a Spiral"
24 November 2005

http://ciclops.org/view_event.php?id=43
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Guest_BruceMoomaw_*
post Nov 28 2005, 02:16 AM
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Actually, it seems as though -- for once -- we have a ring phenomenon so simple in nature that even we unscientific dummies can perfectly understand what's going on. (I was intrigued to see, though, that Prometheus will plow through the F Ring in 2009. That should put on quite a display. We are only now coming to grasp just how changable at least the small-scale features of the rings are over time, as Larry Esposito's vision comes true of small "moonlets" in different parts of the rings slowly hauling in other material despite the Roche Limit, and then periodically getting splashed all over the place again by meteoroid impacts.)
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ljk4-1
post Nov 28 2005, 03:30 PM
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QUOTE (BruceMoomaw @ Nov 27 2005, 09:16 PM)
Actually, it seems as though -- for once -- we have a ring phenomenon so simple in nature that even we unscientific dummies can perfectly understand what's going on.  (I was intrigued to see, though, that Prometheus will plow through the F Ring in 2009.  That should put on quite a display.  We are only now coming to grasp just how changable at least the small-scale features of the rings are over time, as Larry Esposito's vision comes true of small "moonlets" in different parts of the rings slowly hauling in other material despite the Roche Limit, and then periodically getting splashed all over the place again by meteoroid impacts.)
*


Anyone who has read Niven and Pournelle's Footfall knows the REAL reason the F ring is twisted.

http://en.wikipedia.org/wiki/Footfall

cool.gif


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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Chmee
post Nov 28 2005, 05:12 PM
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QUOTE (ljk4-1 @ Nov 28 2005, 11:30 AM)
Anyone who has read Niven and Pournelle's Footfall knows the REAL reason the F ring is twisted.

http://en.wikipedia.org/wiki/Footfall

cool.gif
*


Yes, it amazing what the fusion drive flame from a ship can do to a ring system! Of course, the Fithp have been waiting out there at Saturn since 1980 so it's about time they headed this way... unsure.gif
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mars loon
post Nov 28 2005, 05:26 PM
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More on the F-ring spiral today from space.com

28 Nov 2005

"Saturn Surprise: One Ring is Actually a Spiral"

http://space.com/scienceastronomy/051128_mystery_monday.html
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dilo
post Nov 28 2005, 05:41 PM
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QUOTE (mars loon @ Nov 27 2005, 05:42 PM)
Many more details of this stunning finding are available at the CICLOPS Website

View an informative slide presentation under the headline:

"Cassini Discovers the F Ring Is Embraced by a Spiral"
24 November 2005

http://ciclops.org/view_event.php?id=43
*


Thanks for the link, the "movie" is nice and very clear...
So, for 2009 we have a "Prometheus promise" ! tongue.gif This is another very good reason for a Cassini mission extension! smile.gif


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The Messenger
post Nov 28 2005, 09:57 PM
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QUOTE (BruceMoomaw @ Nov 27 2005, 07:16 PM)
Actually, it seems as though -- for once -- we have a ring phenomenon so simple in nature that even we unscientific dummies can perfectly understand what's going on.  (I was intrigued to see, though, that Prometheus will plow through the F Ring in 2009.  That should put on quite a display.  We are only now coming to grasp just how changable at least the small-scale features of the rings are over time, as Larry Esposito's vision comes true of small "moonlets" in different parts of the rings slowly hauling in other material despite the Roche Limit, and then periodically getting splashed all over the place again by meteoroid impacts.)
*

I don't think it is quite that simple, at least if I understand what appears to be happening - why on each revolution do the rings get smaller? If this is what is happening, why haven't all the rings collapsed, and a long time ago? The moonlets should introduce a periodicity, not a progressive march inward. Where is the braking force? Are there some orbital distances that are more stable than others? Are the rings truly an LP record, or is there a Saturn-iancarnation of Bode's Law??? Stay tuned cool.gif
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