Such is the case for Saturn’s bright ring system. The
bright rings appear bright because they reflect about 60
percent of the sunlight falling on them. Scientists suspected
from their brightness alone that they are made of water ice,
and spectral observations
confirmed this suspicion,
clearly showing the distinct
signature of water. A
slight reddish tint to the
rings indicates that they are not made of pure ice but must
be contaminated with other materials, such as silicates.
The icy moons around Saturn or the frozen comets in the
outer Solar System could easily provide this contaminating
material.