planetary ring system râžmân-e halqehâ-ye sayyâre-yi Fr.: système d'anneaux planétaires → Interplanetary dust and other small particles organized into thin, flat rings encircling a planet. The most spectacular planetary rings known are those around → Saturn, but the other three → giant planets of the solar system (→ Jupiter, → Uranus, and → Neptune) have their own ring systems. |