Faint Ring Thread, Saturn's D, E and G rings |
Faint Ring Thread, Saturn's D, E and G rings |
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Member ![]() ![]() ![]() Group: Members Posts: 509 Joined: 2-July 05 From: Calgary, Alberta Member No.: 426 ![]() |
There are two new "Raw Images" up that give a good view of Saturn's D Ring. As of today (July 17th) they are on the first page of the Raw Images section. The better of the two is image number W00009347.
The very narrow inner ringlet is called D68 and it is the innermost well defined ringlet of the entire ring system -- it's only about 7250 kilometres above the cloud tops, about half-way from the planet to the inner edge of the C Ring. If you search the "Saturn-D Ring" section of Raw Images, there is a nice narrow angle view (N00035241) which I am pretty sure is a close-up of D68. D68 is an oddball, it really is sort of "in the middle of nowhere". The brighter ringlet in the upper right is called D73. About a thousand kilometres inward from D73, there is a noticeable "dark zone". In the Voyager images, there was a third bright narrow ringlet inside this zone, D72, which seems to be gone now, strangely enough. The relevant Voyager images are Voyager 1 image 34946.50, and Voyager 2 image 44007.53. If the diffuse ringlet at the inner edge of the "dark zone" is what is left of D72, it looks to have migrated a bit closer to Saturn in addition to spreading out a lot. (By the way, I'm not making up these ringlet designations on the fly -- they are given in a paper by Mark Showalter that was published in Icarus in 1996, which is pretty much the only major paper on the D Ring.) To give some idea of scale, the three bands of material in the far upper right corner are part of the innermost ringlet of the C Ring (this can also be seen on some images of the rings taken on May 3rd of this year). Since it is so faint and doesn't appear in many images, the D Ring rarely attracts much attention. But it's kind of neat to look at if you haven't seen it before, particularly because of D68, which is sort of the "anti-F ring" in a way. |
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#2
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Junior Member ![]() ![]() Group: Members Posts: 55 Joined: 8-November 06 From: Indiana, USA Member No.: 1337 ![]() |
Personally, I think it is awfully bright to be an undiscovered moon. It is brighter than the Op Nav shots of Pallene and Methone that we are used to seeing. Likewise, that is a lot of orbital motion for the relatively short exposure which looks to me to be a few second given the few stars included.
My vote is it is a clump of larger rocks that appear brighter at this phase angle. |
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#3
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![]() Interplanetary Dumpster Diver ![]() ![]() ![]() ![]() Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 ![]() |
During the ring plane crossing in the 1990s, Hubble spotted quite a few transient clumps in the rings. That may be what this is. It would be awesome if Cassini could get a closeup of one of them, although I realize how difficult that would be.
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