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I heard that Saturn has 62 moons with confirmed orbits, 53 of which have names and only 13 of which have diameters larger than 50 kilometers. Some come within 1km of each other.

How do these moons keep in Saturn's orbit without hitting each other, and someday will these moons collide with each other and be destroyed?

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  • $\begingroup$ Best ask why they are stable or why there are too much stable bodyes. Since they exist for at least a geological era if they are slight instable* they are not here any more. Instable* meaning the risk to hit each other. Or they are just the result of early bigger bodyes impacts. $\endgroup$ – jean Jul 11 '16 at 16:15
  • $\begingroup$ Just like earth artificial satellite don't collides with each other. I don't think they gonna destroy without any external event. $\endgroup$ – roottraveller Jul 14 '16 at 9:36
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Indeed, the situation is temporary on a scale of hundreds of millions of years, with reoccuring instabilities.

The moons don't run into each other in the short term, but the orbits affect each other and are affected by The sun and other bodies in the solar system.

See this presentation by Matija Cuk for details.

Recently the age of Saturn's moons interior to Titan, previously thought to be as old as Saturn, also became actively debated. I will show how computer simulations of the past orbital dynamics of Saturn's moons Tethys, Dione and Rhea can tell us how long they have been around. It appears that the inner moons and rings of Saturn are only about 100 million years, equivalent to the Cretaceous period on Earth. I will also discuss how the present moons likely originated from debris resulting from a major orbital instability in which the previous generation of icy moons was destroyed.

You ask “someday will these moons collide with each other and be destroyed?” so the answer is yes, at least the inner group. So having 62 (a lot of them) is not the issue; the outer part is stable over billions of years.

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The various moons are on orbits that are mostly a lot more than 1km apart from other moons. The orbits are stable, so the moons just keep going round Saturn on the same orbit. The moons are far enough apart that they have negligible gravitational influence on other moons. So the moons never get close to each other and don't collide. There are moons, like Daphnis and Atlas that can come with 1000km of each other, but they are very small. No moons come within 1km of each other.

There are some exceptions to this: Janus and Epimetheus orbit at nearly the same distance from Saturn. If they stayed like this they would collide within each other within about 4 years. However as one moon starts to catch up with the other, it is pulled forwards, causing it to move out, and slow down. Letting the other moon move inwards and faster. The two moons essentially swap orbits. Although there is only about 50km between the orbits, the two moons never approach closer than 10000km, so are not at any risk of collision.

Moon collisions can take place, one theory on the origin of the rings is they they were formed from a moon that broke up, either from a collision or by Saturn's gravity (It's not the most popular or recent theory). Collisions have never been observed, nor are any forecast to occur for as long as we can predict.

Of the 62 moons, remember that some of them are extremely small: a few tens of metres across, and there is no clear division between "small moon" and "large clump of ring material"

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