NASA / JPL-Caltech / SSI / animation by Mike Malaska
Spinning spokes in Saturn's rings
Cassini captured this 22-frame animation of the "spokes" in Saturn's rings on September 7, 2009. Scientists think that the spokes are made of fine dust electrostatically levitated above the ring surface, made more visible by the low-angle lighting that occurs near equinox. (It may also be possible that the spoke phenomenon only occurs at this season; scientists don't yet know for sure). The images were aligned and their contrast adjusted to make this animation smooth. A higher-resolution version can be downloaded from Mike Malaska's flickr page.