Dramatic edge-on Cassini views of Saturn's E ring, like these side-by-side images, reveal for the first time a double-banded structure similar to that of Jupiter's gossamer ring and to the bands of dust found within the Sun's asteroid belt. Scientists believe now that the E ring particles have their origins in the geysers erupting from the south polar of Enceladus.
The double-banded appearance exists because there are fewer particles close to the ring plane than 500-1,000 kilometers (300-600 miles) above and below. This circumstance can arise if the particles comprising the ring circle Saturn on inclined orbits with a very restricted range of inclinations.
This special condition might exist for two reasons. Either the particles being jetted out of Enceladus and injected into Saturn orbit begin their journey around Saturn with a certain velocity, and consequently a finite (or restricted) range of inclinations, with respect to the ring plane.
Or the particles may begin with a large range of inclinations, and those orbiting very close to the ring plane get gravitationally scattered and removed from that region by the passage of Enceladus.
Scientists will continue to observe the E ring from various angles to confirm the structure, and will input their observations into dynamical models to show how the particles might end up in such a configuration.
Most of the bright specks in the images are background stars, although a few are cosmic ray hits on the camera's detector.
The two images were taken five hours apart on Dec. 1, 2005 when Cassini was approximately 1.9 million kilometers (1.2 million miles) from Saturn. The image scale on the sky at the distance of Saturn is about 220 kilometers (137 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.