The Cassini spacecraft is giving astronomers a wealth of new information about Saturn and its ring system. It's also tossing in some surprises and questions along the way.

Take the latest images from the spacecraft's Visual and Infrared Mapping Spectrometer (VIMS), as it passed into Saturn's shadow in September. They show the rings in varying hues: the E and D rings are blueish, while the C ring tends more toward red, and the G ring is a light green. Then there's variation within the rings: E, for one, blends from red to blue in an asymmetric pattern with no obvious explanation.

"We would like to think there was a simple relation between color and composition -- that would make life very easy," said Phil Nicholson, Cornell professor of astronomy and VIMS team member. But the particles also may be scattering different wavelengths of light based on their size, he said. That leaves researchers looking for a way to pin down the relationship between particle composition, size, and apparent color in order to explain how size and composition relate to the particles' positions within the rings.

Then there's the question of the missing moons. Diffuse rings, like the four recently discovered, are thought to form from material dispersed from a moon that collides with another moon or a passing object. No moonlet has yet been found for two of the new rings, though; and a newly discovered moonlet, Methone, has no corresponding ring.

"We are making progress understanding these things," said Cassini team member and Cornell postdoctoral researcher Matt Hedman. But finding the unexpected, added Nicholson, keeps life interesting. "It's nice to be surprised once in awhile," he said.