Major satellites cause wavy deformation of Saturn's rings
Abstract
THE rings of Saturn consist of many solid particles, each revolving around Saturn as an independent satellite. Typical particle size or, more exactly, mean particle radius, ρ, has been estimated from radio interferometry and radar observations to be 215 cm (refs 1, 2)consistent with a ring thickness of just over 10 m. However, the ring thickness z_{o} as determined photometrically is at least 4 orders of magnitude greater, at 13 km (refs 3, 4). The generallyaccepted explanation for this difference is that the particle orbits are not fully coplanar, but inclined to the mean ring plane at appreciable angles i_{p}. However, such a model would be unstable. Indeed, particle collisions must be frequent as each particle crosses the mean plane twice for one revolution and the probability of meeting another particle is high. As a result of collisions, the energy of particle movement normal to the mean plane is dissipated, and so very soon the particle orbits must become coplanar, that is z_{o}>2ρ_{max} where ρ_{max} is very likely much less than 1 km. I show here that allowing for gravitational perturbations of particle orbits by satellites and the oblateness of Saturn one may obtain a model satisfying the observational data. The main features of the model are: (1) specific wavy deformation of the rings which thus appear twistedthis is the consequence of differential precession of particle orbits with i_{p} ≠ 0; (2) particle collisions are rare (and there is therefore only slow energy dissipation) because the neighbouring particles move in nearly the same phase.
 Publication:

Nature
 Pub Date:
 May 1978
 DOI:
 10.1038/273284a0
 Bibcode:
 1978Natur.273..284B
 Keywords:

 Astronomical Models;
 Natural Satellites;
 Saturn Rings;
 Orbit Perturbation;
 Particle Collisions;
 Particle Motion;
 Planetary Rotation;
 Precession;
 Thickness;
 Lunar and Planetary Exploration; Saturn; Satellites of Saturn;
 SATURN;
 RINGS;
 SATELLITES;
 PARTICLE INTERACTIONS;
 PERTURBATION;
 DEFORMATION