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Some planets, specifically Jupiter, Saturn, Uranus, and Neptune in our solar system, have planetary rings.

Jupiters rings, cross section

Why do some planets have rings? How are they made and from what? Most importantly, will I be able to observe the rings on any planet with an amateur telescope?

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up vote 18 down vote accepted

Rings are made up of tiny (and not so tiny) pieces of rock and ice that are in some way the bits "left over" from the formation of the planet. The theory involves the Roche limit - and is that particles that are already within this limit can't accrete into a larger body because of the tidal forces involved.

Another theory is that they are formed when a moon comes closer to a planet than the Roche limit, the tidal forces cause it to break up and form a ring. Though the presence of "shepherd" moons in the rings of Saturn does hint that this may not be major source of material.

Both explanations, to me, imply that you'd only get major ring systems around larger (gas giant) planets, though it doesn't preclude rings around smaller (rocky) planets. This seems to be borne out by our solar system where the gas giants have rings whereas the rocky planets don't.

Source

As to being able to see them, you should be able to see the rings of Saturn with an amateur telescope which has a 50 - 100 powers of magnification. With binoculars you'll probably see a misshapen blob.

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Your best bet is a telescope at least 50x magnification. Over 100x you will get decent visibility of the rings. – Rory Alsop Sep 27 '13 at 9:41
    
I think being distant from the sun helps too. All the rocky planets in our solar system are close to the sun and the large ones further out. I'm not sure a gas giant could keep a ring system if it was as close to the sun as earth or mars. – userLTK May 5 '15 at 2:46
    
In an estimated 50 millions years, Phobos will also get crushed by Mars' gravity. Will it form a ring ? Who knows... But I'm pretty sure this is possible :p Though I agree with you on the fact that gas giants have rings more often due to their huge gravity, I wouldn't consider rocky planets having rings impossible. Universe is big. – Nico Jan 13 at 8:14

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