# Why does Saturn have both moons and rings?

From my understanding, a ring can form around a planet when a moon gets too close to its Roche limit, and gets ripped appart by the planet's gravity pull. That makes sense to me, but I don't understand why Saturn has both moons and rings at the same place.

I know the F ring is supposedly created by Enceladus' rejections, but I don't get why Pandora and Prometheus are not ripped appart as well as the ancient objects that formed the ring they are in.

I couldn't find specific explanations for this. Does it have any link to the moon's density?

• Jupiter has both rings and moons too. The rings are just dust particles tho. – ott-- Jul 30 '16 at 10:38

You're right that density is the important thing here. The Roche limit is the distance from the main body $d$ such that $$d=1.26R_M\left(\frac{\rho_M}{\rho_m}\right)^{\frac{1}{3}}$$ where $_M$ denotes the main body and $_m$ denotes the satellite.