Discoveries in Saturn's Dark
Such a perspective reveals many new things. First off, the team uncovered two new rings made of tiny dust particles, and they confirmed the existence of a couple others. Second, rings and moons are intertwined. "When you see a ring, there is likely to be a satellite," says Joe Burns (Cornell University). Sure enough, one of the finds is associated with the moonlets Janus and Epimetheus, and a second overlies the orbit of a tiny moon called Pallene.
Two other new rings were spotted inside the dark, narrow Cassini Division, though the moonlets associated with them have thus far avoided detection. "Maybe they formed when a moon broke apart," says Burns, speculating on where the missing satellites might be.
The image also contains two tantalizing treats. Upon closer inspection one sees geysers spewing from the icy moon Enceladus. These cyrovolcanic eruptions supply the material of the E ring. And in the top-left corner of the view is a special little dot: Earth shining in the background.
In other ring news, Cassini scientist Matt Hedman (Cornell University) announced a facinating find concerning Saturn's D ring, the innermost. He determined the three-dimensional shape of the ring and found that it isn't flat like the rest. In fact it appears "vertically corrugated like a tin roof." The bands within it are spaced 30 kilometers apart. Hedman compared these findings to images taken from the Hubble Space Telescope in 1995, and found that 11 years ago, the same bands were spaced 60 kilometers apart.
When he combined the rate at which the spacing is changing along with the vertical structure of the ring, Hedman came up with an amazing result: "We have evidence that the D ring was recently disrupted by impact. Perhaps a comet or meteorite passed through the ring system," he says. Calculating backward in time, in 1984 something plowed through the D ring and "gave it some angular momentum, lifting it out of the plane." According to Hedman's models, it only takes a body a few meters across to kick up enough dust to match what we see.