Re: Tidal forces?
The force of gravity grows stronger, the closer you approach a massive object such a a star or gas giant like Jupiter. Now consider a planet or moon orbiting such a massive central body. There's a critical distance, known as the Roche Limit, where the difference between the force of gravity on the star/planet-facing side is so much greater than the force of gravity on the side furthest from the star/planet that it tears the orbiting body apart. This is a likely scenario for how Saturn's rings were formed: a small satellite's orbit took it so close to Saturn that the differential gravitational forces ripped it apart. It's also the fate that awaits Phobos and Deimos, the moons of Mars, which are slowly spiralling in towards the planet.