New ring discovered around Saturn |
New ring discovered around Saturn |
Oct 7 2009, 10:27 PM
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#16
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
not necessarily. As I pointed out before, for example, Janus and Epimetheus have a similar dust ring at their orbits made of micrometeorite ejecta and they have a prograde orbits around Saturn.
And adding to my list of "Moons with rings at their orbits", I should have also added Pan and Atlas. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Oct 9 2009, 01:12 PM
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#17
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Member Group: Members Posts: 237 Joined: 22-December 07 From: Alice Springs, N.T. Australia Member No.: 3989 |
News of the new Saturnian ring has travelled fast. Without being chauvinistic, I am glad to say I come from a forward looking scientifically literate country.......... our only quality national daily 'The Australian' has been quick to snaffle up this newsworthy item and give it a prominent place today. Who says we're behind the times down this way??????
Round here it's out with the delta Vs and albedo calculations and back to the good old trines and sesquiquadrates ! Perhaps I'll swallow national pride and keep checking the UMSF pages ! |
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Oct 9 2009, 01:20 PM
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#18
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Member Group: Members Posts: 599 Joined: 26-August 05 Member No.: 476 |
Unenviable that you have astrologers finding a giant ring around Saturn.
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Oct 9 2009, 03:56 PM
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#19
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Would it be shorter to write a list of Saturnian moons that DON'T have associated dust rings? And would the same not be true of...er...anywhere with moons?
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Oct 9 2009, 05:19 PM
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#20
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Member Group: Members Posts: 754 Joined: 9-February 07 Member No.: 1700 |
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Oct 9 2009, 07:10 PM
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#21
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Member Group: Members Posts: 259 Joined: 23-January 05 From: Seattle, WA Member No.: 156 |
not necessarily. As I pointed out before, for example, Janus and Epimetheus have a similar dust ring at their orbits made of micrometeorite ejecta and they have a prograde orbits around Saturn. And adding to my list of "Moons with rings at their orbits", I should have also added Pan and Atlas. I wasn't very clear there... what I meant was, "might Phoebe's retrograde orbit have something to do with how huge the ring is, by contributing to higher-velocity impacts that would produce more ejecta and/or more widely-scattered ejecta, when compared with the rings formed by impacts on other moons?" But I'm having a hard time figuring out how that might work, anyway. If Phoebe's a captured TNO, maybe it's just got a higher volatiles concentration, and the ring's a toroidal comet tail. |
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Oct 10 2009, 03:22 AM
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#22
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Senior Member Group: Members Posts: 1426 Joined: 26-July 08 Member No.: 4270 |
Back during the Cassini flyby of Phoebe, I recall them saying that Phoebe was confirmed not to be a captured body. Is my memory faulty? (It was a long time ago.
-------------------- -- Hungry4info (Sirius_Alpha)
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Oct 10 2009, 04:52 AM
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#23
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
I don't know how they could have confirmed that, frankly. The retrograde orbit alone is practically a smoking gun; AFAIK, all other known retrograde satellites are thought to be captured.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 10 2009, 10:16 PM
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#24
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Newbie Group: Members Posts: 16 Joined: 10-March 06 Member No.: 700 |
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Oct 11 2009, 02:14 AM
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#25
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Interesting! Could you please describe some of the others, Anne?
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 12 2009, 09:08 PM
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#26
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
One idle thought led to another: I wondered if Cassini got whacked by any Phoebe ring particles as it passed through on its way in to SOI. Then I realized there's an instrument on Cassini designed to measure that, the CDA. Of course, that data's old enough that it's in the PDS. If I had time, I'd dig into it and see if I could understand or deal with the CDA data. I don't have time, though, so I just sent an email to the CDA team leader asking about it and hope I'll get a reply. But I thought I'd mention it here, just in case anybody else feels like attempting to dig into the PDS and see what CDA data looks like!
--Emily -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Oct 14 2009, 04:12 AM
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#27
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
Still an artist's impression. But the article said the discovery was made using Spitzer when it still had cryogen, and that the observations were of basically empty space. Finally saw a "real" photo somewhere: http://apod.nasa.gov/apod/ap091013.html Original here: http://www.spitzer.caltech.edu/Media/relea...c2009-19a.shtml |
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Nov 2 2009, 09:03 PM
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#28
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Newbie Group: Members Posts: 16 Joined: 10-March 06 Member No.: 700 |
Interesting! Could you please describe some of the others, Anne? Sorry to take so long to answer this! Some of those 'other scenarios' explored the possibility that Phoebe at one time or another exhibited Chiron-like activity. The two objects have similar colors and perihelion distances; however, Phoebe appears to have more water on its surface (seen in near-infrared spectra) than Chiron does. Other possible sources of dust considered were collisional, from both major impacts and micrometeoritic erosion. |
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Jan 24 2014, 06:27 AM
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#29
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
I resurrect this years old thread to post this: the Cassini ISS instrument has apparently managed to image the Phoebe ring
First observations of the Phoebe ring in optical light |
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Jun 10 2015, 06:54 PM
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#30
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
a new article in Nature on WISE observations of Phoebe's ring
Small particles dominate Saturn’s Phoebe ring to surprisingly large distances |
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