Final answer:
Saturn's rings look bright because they reflect sunlight. The material in the rings ranges from large boulders to fine dust, all of which have reflective surfaces, especially in the dense and bright B Ring.
Step-by-step explanation:
Saturn's rings look bright because light from the Sun reflects off the material in the rings. The rings are composed of countless small particles that range from mountain size to mere grains of dust, all in orbit around Saturn's equator. These particles are incredibly reflective, making Saturn's rings the easiest and most vibrant to see when compared to other giant planets like Uranus and Neptune. The B Ring, in particular, is the brightest and has the most densely packed particles, making it highly reflective of sunlight. It's important to note that the rings do not create their own light; rather, they are illuminated by sunlight that is either reflected directly from above or has diffused through gaps in the rings.