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Posted by: TheAnt Dec 8 2016, 05:04 AM

The bulge of Saturn and the moons migrating outward faster than expected (for Rhea 10 times faster) adds to the evidence that Saturn's moon system is younger than the planet itself.
http://mediarelations.cornell.edu/2016/12/07/saturns-bulging-core-implies-moons-younger-than-thought/
Related but somewhat different information for the one who is interested in Saturn's shape from https://www.obspm.fr/first-determination-of-saturn.html

Posted by: vikingmars Dec 8 2016, 07:48 AM

Dear TheAnt, thanks a lot for the info
And here is the link to the very nice (and educational) video put online by the Paris Observatory :
http://www.dailymotion.com/video/x52esp2_saturne-un-ecosysteme_school (French)
http://www.dailymotion.com/video/x52eoio_saturn-an-ecosysteme_school (English)
It explains, inter alia, how the satellites were created looong ago from an even bigger (and more massive) ring system and how thery are still created today but with much smaller sizes.
Enjoy

Posted by: nprev Dec 9 2016, 05:50 AM

ADMIN NOTE: Edited topic title and description for brevity & clarity.

Posted by: OWW Dec 9 2016, 11:46 AM

If the inner moons are relatively young, then why are they more heavily cratered than an ancient Lunar Mare? Just look at Tethys; huge impact basins and pockmarked on literally it's entire surface. It doesn't look "young". I'm skeptical.

Posted by: Gerald Dec 9 2016, 02:05 PM

Crater counting might suggest a higher age in such a highly populated region. The moons should have formed by impacting. Who knows how hard their surfaces are, and which impact velocities are required to cause cratering.

Posted by: JRehling May 2 2017, 02:36 AM

Any world with a single process shaping the entire landscape will show that one process everywhere; it doesn't matter if it happened four billion years ago or in the nineteenth century. Accretion and saturation impacts will leave a surface that shows saturation with impact craters everywhere. Whatever stuff accreted the saturnian moons in Saturn orbit wouldn't be the same population that cratered the Moon.

Posted by: MichaelPoole Nov 30 2017, 03:57 PM

But the craters don't look fresh like craters formed just 100 million years ago would look. Look at Tycho on the Moon. It does not look like craters on Tethys or Rhea.