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NASA / JPL-Caltech / SSI
The Saturnian moon Daphnis and Pan stir ripples in the giant planet's rings due to their gravitational effect. Five-mile-wide Daphnis (lower left) is perturbing particles in Saturn's A ring, while 17-mile-wide Pan (upper right) has kicked up dark wakes in the ring propagating toward the middle of the image. This picture was taken in visible light by the Cassini spacecraft's narrow-angle camera on June 3, 2010, at a distance of about 329,000 miles from Saturn.
This image from NASA's Cassini orbiter shows why Daphnis and Pan are known as "shepherd moons": The gravitational influence of those tiny satellites help keep Saturn's giant rings in line, creating subtle ripples and waves in the process.
Five-mile-wide Daphnis, at lower left, makes its circuit around Saturn in the Keeler Gap, an open space in the planet's A ring. As it passes through, it perturbs the particles along both sides of the gap, sculpting the edges. To learn more about Daphnis' influence and watch a movie showing the shepherd at work, check out this Web page from the Cassini mission's imaging team.
Meanwhile, 17-mile-wide Pan performs a similar function in the A ring's Encke Gap at upper right. You can see the dark waves left in the moon's wake by its gravitational influence on the icy particles in the disk. The images on this Web page provide additional perspectives on Pan. Such effects, documented in detail during Cassini's eight years in the Saturnian system, explain why Daphnis was named after a shepherd in Greek mythology, while Pan was named after the god of shepherds.
More about Saturn's moons and rings:
- Saturn moons star in dark drama
- Spot the specks of Saturn's moons
- Video: Guided tour of Saturn's rings
- Slideshow: Greatest hits from Cassini
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
Leave a Comment:
Is that cool or what .....
Not only the ripples in the rings ....
Wouldn't you also assume that the gaps were or could have been created by the "shepherd moons" .... ??
Great amazing photo ....
Thanks Alan ....
I would postulate that the Shepard Moons are accretions of ring material that are swepping those gaps clean as they grow in size.
That's some real fancy talking there Kevin .... "LOL"
But I think you might be right ....
Yeah, he can use big words but can't spell "sweeping". ROFL! I hate when my fingers are too fast for my thoughts and hit the wrong keys too :)
However, Kevin, all admensuration aside, my thoughts are harmonious with your entire epistle.
I often refer to saturn system as the second biggest particle accelerator in the solar system, and, we are foolish for not using it as such....as well, this is certainly one of the most poignent demos of gravity's odd outcomes and intereactions...sutitable for many a physcis lecture!!...onwards
thanks for the decade of science alan, hope there will be plenty more....
In the eighties I spent many a night with a very large nasa text on the Sat system, my focus was on the Spokes....at the time they were believed to be large lightning discharges from the rings down to the planets (surface?) atmosphere....a very interesting phenomenom that is rarely commented upon anymore, perhaps due to a lack of their prominece in current cassini photos.....just wanted to make sure they are not forgotten. During their season, they are very interesting and quite fearful for mission planners considering ring flybys....
Saturn is one of the most beautiful planet systems in our solar system. This picture is well worth the proverbial thousand or so words IMHO. Amazing - 329,000 miles away and the clarity is astounding. Great job Cassini team.
Awesome and breath-taking at the same time!!!
If Congress (the opposite of progress) would only boost NASAs funding, we would be able to see many more of the wonders right in our cosmic backyard. These flagship missions are incredible!
Bigben, I'm pretty sure that the moons do cause the gaps; probably also "growing" the moons at the same time, which would increase the gap size, etc. etc. Don't think we'll run out of rings in our lifetime anyway.
Hey andyo ....
You might be right ....
That little moon might scoop up or has already scooped up mass and could scoop up more matter and mass resulting in a growing moon ....
Cool observational thought ....
"If Congress (the opposite of progress) would only boost NASAs funding, we would be able to see many more of the wonders right in our cosmic backyard. These flagship missions are incredible!"
That idea seems to be based on the assumption that if it happened, every single department, every single project in NASA would have its budget doubled...it would never be that simple.
Some managers (or forces outside of NASA) would still jockey to get their preferred projects and departments disproportionately more of this now-larger pie, depending on who you ask, some projects are ill- founded and don't deserve another dime, no matter how deep our pockets are (I can easily name one, but I won't get into it here), some are good ideas, yet poorly managed and would be 'rewarded' with more money.
A few programs are doing just fine on their current budgets, and just don't need more,
This is why the good Dr Tyson's proposal to make NASA's percentage of the Federal Budget one full percent, rather than the current .5% just would not work (or at least not get the desired results). He says he wants to avoid the politics of who gets how much with this proposal, but in a government agency, the politics never go away...
Wow. A gravitational "wake" kicked up within the dusty material of the wider ring by the passing planet. Or, in the case of tiny Daphnis, also by the inward ring material speeding past on the inside track.