The researchers report that they were studying the planet's rings, which are collectively called Eta, and discovered that they had an oddly shaped orbit -- not round or even circular. Instead, they describe it as sort of triangular. More study showed that the odd orbit of the rings was due to gravitational pull from Cressida -- one of the planet's moons. The gravitational impact is exaggerated, they note, due to the moon keeping pace with the orbit of the planet. The particles in the ring, on the other hand, move faster than the moon. This results in the moon tugging...