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Saturn Rings But No Spokes
An anonymous reader writes "Scientists continue to ponder why images of Saturn's rings today lack the 'spokes' or dark radial bands radiating outward and first observed on the Voyager flyby. The Boulder-based Cassini Image Team describes 5 visible moons, plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now."
I'm sorry, maybe I'm just an idiot, but I don't really see any of the 'spokes' in the image you linked to.
Could somebody paste a big red arrow on there for the outer-space-cluefully-impared, such as myself?
Thanks.
There were no real current Astonomy Picture of the Day references so I linked to a search on Saturn. This gives quite a few different views of Saturn and some other related material as well.
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
By the way, next summer NASA's Cassini spacecraft, launched in 1997, is scheduled to go into orbit around Saturn and its moons for about four years.
The piggybacking Huygens probe is scheduled to go into the hazy Titan atmosphere and land on the moon's surface (if all goes well). The Huygens probe is geared primarily towards sampling atmosphere. The probe is equipped to take measurements and record images for up to 30 minutes on the surface. But the probe has no legs, so when it sets down on Titan's surface its orientation will be random. And its landing may not be by a site bearing organics.
Please help publicise swpat.org - the software patents wiki
The "spokes" are odd disruptions in the rings caused by Saturn's magnetic field rotating through them. They show up as dark patches radiating directly away from Saturn or occasionally arching, and they travel like a wave around Saturn in time with its rotation. It was this timing/speed that tipped astronomers off as to what was causing them, incidentally.
So if the spokes aren't visible now, maybe Saturn's magnetic field is fluctuating/less coherent than normal. It's a gas giant so its field could be less stable than the denser planets. There may be some low-level eg mid-atmosphere storm disrupting the normal field-generating circulations.
Just a thought. IANAA
cheers, Sal
--
Sal
Writings: saltation.blogspot.com
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Perhaps the spokes don't show up because they're not applying those same techniques? I certainly don't see any mention of those techniques in the article in the first link.
libertarianswag.com
This is an offtopic comment: offtopic because it was stolen verbatim from a totally unrelated story:
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http://science.slashdot.org/comments.pl?sid=793
It's just an excuse to get the
It's clearly unrelated to this topic. 2 seconds with Google gives us:
8 6& cid=7019194
.sig modded up.
http://science.slashdot.org/comments.pl?sid=793
It's a troll because it's a stolen post used for the purpose of getting a
Why was this modded offtopic? I'm guessing the moderator didn't recognize what he was talking about. I was actually looking to see if there was a Fithp post before I posted.
Background, in the Niven book 'Footfall', the first indications they see of the incoming alien invasion is weird, spoke-like distortions in the rings of Saturn.
have been seeing spokes in the rings for quite some time using ground-based telescopes of various sizes. This may be one of those features, like the canals on Mars, that shows up because the eye-brain software processes images differently than the spacecraft ccd-computer does. An article in Sky & Telescope discovered they could reproduce the canal effects using the techniques of registration (stacking), and various applications of wavelets and other processing methods. They concluded our eye-brain mechanism does something similiar in real time at the eyepiece during moments of steady seeing conditions, causing dark lines to be seen where a smoother color gradient actually exists.
In all the APOD picture of Saturn I found a reference to Spokes and a picture that contains them.
Use your head, can't you, use your head,
You're on earth, there's no cure for that - S. Beckett
I was a young engineer at JPL when Voyager 2 encountered Saturn, and I remember when the first photos of the spokes in the rings were displayed in real time on the monitors in the cafeteria. The work on other projects had pretty much ground to a halt while everyone watched the data come in.
Of course, the real time data had no captions, no explanations of what we were seeing, so we had all sorts of guesses - density waves, camera artifact, etc. Once it was apparent that the waves were holding together as the rings rotated and were not being sheared apart, it was clear they were not due to any gravitational effect. Since they moved with the rotation of the planet, the accepted explanation is the magnetic field of Saturn causing the charged dust in the rings to concentrate into visible spokes. As I understand it, the spokes are not a wave phenomenon at all.
"plans for the descent probe going into the Titan moon's hydrocarbon-rich atmosphere and the expected orbital entry around Saturn less than 4 months from now."
All Iraq-related kidding aside, I find this interesting. Saturn is too far out for modern solar energy solutions to be viable, we still haven't figured out the whole fusion thing and hydrogen doesn't like to be cracked out of water. On the other hand, hydrocarbons want to be broken down and we know all about harnessing the energy of that reaction and we'd have uses for the byproducts (soot may not be desirable here on earth but carbon is a pretty good radiation shield). We can do something with this once we get there.