Final answer:
The rings of the gas giants are composed of countless small particles with varied structures and compositions; Saturn's rings are mostly water ice, while Uranus and Neptune's rings contain darker, less massive particles. Moons play a significant role in the maintenance of ring structure, and the rings' origins are still not fully understood.
Step-by-step explanation:
The rings of the gas giant planets are composed of billions of small particles. For instance, the rings of Saturn are made of mostly water ice particles, with some gaps where the moon Enceladus contributes by erupting geysers of water that maintain the tenuous E Ring. In contrast, the rings of Uranus are narrow, separated by wide gaps, and contain dark particles with much less mass. Neptune's rings are similar in composition to Uranus's but contain even less material.
Each ring system's complicated structure is often the result of interactions between particles and moons. While the origins and ages of these ring systems remain somewhat of a mystery, one theory suggests that the rings of Saturn could have formed from the disruption of a moon similar in mass to Mimas. In contrast, the differences in appearance, such as the bright particles in Saturn’s rings versus the darker particles in Uranus and Neptune’s rings, could be due to their different chemical compositions and the absence of significant amounts of bright water ice. If Saturn's moons were removed, the rings would likely disperse over time because the moons play a critical role in maintaining the rings' structure.