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Iapetus equatorial ridge fell from the skies! 
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#1
Apr1914, 04:36 AM

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P: 436

Moons of Saturn have always been mysterious. The Iapetus equatorial ridge is now seen as exogenic, according to these people:Discover_MagazineIapetus.
Also, the wiki says that equatorial ridges are unique to the Saturnian system. 


#2
Apr1914, 05:12 AM

P: 697

There's also tidal friction, which causes the material in the rings to either spiral outwards(like our Moon does) or inwards, depending on the orbital velocity. 


#3
Apr1914, 05:49 AM

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P: 436

Thanks Bandersnatch. And what factors affect the Roche limit? Like if a planet is extraordinarily huge but has weak gravitational field, the limit may lie within the planet's surface..etc. I found this formula on wiki but it does not include the rigidity factor of the orbiting body
##d=1.26R_m{\Big({\frac{M}{m}}\Big)}^{1/3}## 


#4
Apr1914, 06:58 AM

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Iapetus equatorial ridge fell from the skies!



#5
Apr1914, 11:56 AM

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#6
Apr1914, 12:06 PM

P: 697

On the wiki page, you can find the derivations for two extreme cases of an ideal rigid and fluid body. The two differ by the numerical factor in the equation  1.26 and 2.44. The actual nonideal bodies will lie somewhere inbetween. Additionally, the Roche limit as expressed by the above equation concerns only bodies held together solely by their gravity. It does not take into account any other forces that may affect cohesion, so, for example, a human being within Roche limit of Earth(~27 000 km for a ~1g/cm^3 dense human body) does not disintegrate, as other forces than gravity hold his body together. I've never seen the actual calculations for realworld cases, but I hear they're not trivial. 


#7
Apr2014, 04:07 AM

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Are the rings of saturn (or any other planet with ring system for that matter) present inside the Roche limit of the planet? 


#8
Apr2014, 05:19 AM

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For Saturn, some of the rings are inside and some are outside. I didn't check the other planets.



#9
Apr2014, 05:51 AM

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