A possible link between the rotation of Saturn and its ring structure

We present here evidence that two previously unidentified, yet conspicuous gaps in Saturn's rings lie at distances corresponding to 2/3 and 4/3 of the planet's rotation period. Gaps such as these can be produced in a ring of large bodies or small uncharged particles only by a non-axisymmetric gravitational field (both of the above can be associated with the l = m = 3 harmonic), a fact that is relevant to models of planetary interiors.