EFFECTS OF PLANETS AND THEIR SATELLITES UPON EACH OTHER

Tidal Locking

Tidal lock is a state in which any celestial body in orbit around another, usually heavier body keeps the same face toward the other body. The rotation of such a body is thus synchronous. The classic example of tidal lock is the attitude of the Moon of Earth.

Shepherding

Shepherding moons are satellites that orbit along side a ring. Due to gravitational effects from the shepherding moon, the edges of the rings are kept sharp and distinct. If the shepherding moon was not present, then the ring material would have a tendency to spread out. If two satellites are orbiting on both sides of the ring, then ring will be constrained on both sides into a narrow band.

Resonance

When you push on a pendulum at just the rate that the pendulum naturally swings, the effects add up and lead to a very large effect. This phenomenon is called "resonance." In a similar vein, ring particles have natural response frequencies based on their orbital motion. Nearby satellites have small gravitation effects on the ring particles, but at resonance locations the effects can be quite pronounced. Many of the structures in planetary ring systems have been associated with the resonant effects of nearby moons.