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Fraser
2005-Aug-18, 04:59 PM
SUMMARY: Saturn's rings are separate from the planet they circle, and then even have an atmosphere of their own. During several flybys, Cassini has been able to detect very small amounts of molecular oxygen floating around the rings. Molecules of water are broken apart by ultraviolet light from the Sun; the hydrogen and some of the oxygen is lost into space, and some of the oxygen is frozen back into the rings. But there's enough of a cloud of these atoms around the rings that this process must be ongoing and kept in a continual balance.

View full article (http://www.universetoday.com/am/publish/saturn_ring_have_own_atmosphere.html)

What do you think about this story? Post your comments below.

Eric Vaxxine
2005-Aug-19, 02:26 PM
It still amazes me that these rings appear so stable?

I know Phobos is falling towards Mars, but is every other moon/moonlet/planet all so stable?

Or is it the millions of years time frame which we live outside of,
that make it all seem so calm?

VanderL
2005-Aug-19, 04:34 PM
From the article (my bold):



Dr Coates said the ring atmosphere was probably kept in check by gravitational forces and a balance between loss of material from the ring system and a re-supply of material from the ring particles.

"Probably"? How else can these this atmosphere be "kept in check"?

Cheers.

Duane
2005-Aug-19, 07:42 PM
There "probably" isn't any other explanation, so this one is "probably" correct. VanderL, I thought you didn't like "definate" explanations in the absense of being there?

cran
2005-Aug-20, 03:03 AM
Is it an assumption, or is it established that the gases are 'gravitationally bound' to the rings, and not simply part of the evaporative process...? :unsure:

ie, is it really an 'atmosphere' or is it an ephemeral 'gaseous envelope' driven by interaction with the solar wind and UV radiation? :huh:

VanderL
2005-Aug-20, 08:40 AM
Originally posted by Duane@Aug 19 2005, 07:42 PM
There "probably" isn't any other explanation, so this one is "probably" correct. VanderL, I thought you didn't like "definate" explanations in the absense of being there?
We're very close to "there" in this case, at least close enough to resolve details, the "probably" in the text surprises me, because the authors don't say what else is considered. To answer cran, any atmosphere will be dynamic, the rings are a transient phenomenon, so too will be the atmosphere of the rings.


Cheers.

cran
2005-Aug-20, 11:04 AM
Sorry VanderL, I wasn't asking if it dynamic; I would expect it to be in either case ... I was asking if it is established that it is gravitationally bound (therefore an atmosphere) or simply interacting and escaping into space (a gaseous envelope)? :huh: how does 'dynamic' not fit into either scenario? :blink:

I guess I was just wondering what was meant by 'atmosphere' in the initial report; ie, how accurate is the terminology, mainly so that I can then 'picture in my mind' what dynamics might be playing out there? :wacko:

In my learning, one property of an atmosphere is to be gravitationally bound to the object and therefore a part of the object being considered ... and to preempt, all atmospheres, as far as I am aware, release gases to space. :ph34r:

Jerry
2005-Aug-22, 05:17 PM
Originally posted by cran@Aug 20 2005, 03:03 AM
Is it an assumption, or is it established that the gases are 'gravitationally bound' to the rings, and not simply part of the evaporative process...? :unsure:

ie, is it really an 'atmosphere' or is it an ephemeral 'gaseous envelope' driven by interaction with the solar wind and UV radiation? :huh:
...If this is a "true" atmosphere, the density of the rings would have to be much higher than current models suggest - more rocky stuff, and I think it is showing up, too:

http://www.spaceref.com/news/viewsr.html?pid=17802

cran
2005-Aug-22, 05:33 PM
I guess that's why I was wondering... :huh: