Weird & Interesting science, take 2

[robkelk]

Ring system discovered around dwarf planet Quaoar leaves astronomers puzzled

The Roche limit states that ring systems can only form within a distance where the tidal forces from a larger body are more powerful than a smaller object's own gravitational forces. In short, debris captured inside a planet's Roche limit will be ripped apart and compressed into a ring system. Any material outside this distance, however, will more likely stick together under gravity and form a moon instead.

Quaoar, however, breaks this rule. Its ring system is intact at orbits at a distance over seven times the dwarf planet's radius. Saturn's ring system is located at a distance only three times its radius, for comparison. Now astronomers are puzzled over how such a ring system can survive so far from its parent body.