CICLOPS: Cassini Imaging Central Laboratory for OPerationS

The Enceladus Ring
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The Enceladus Ring
PIA 08163

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The Enceladus Ring
PIA 08163

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  This excellent view of the faint E ring--a ring feature now known to be created by Enceladus--also shows two of Saturn's two small moons that orbit within the ring's extent.

The E ring extends from three to eight Saturn radii (its full extent is not visible in this view).

Calypso (21 kilometers, 12 miles across) and Helene (33 kilometers, 21 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front of or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ring plane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in the Jupiter's gossamer ring). Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles initially have a certain velocity out of the ringplane, and so the particles are created with finite (or restricted) inclinations.

Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally scatters any particles that lie very close to the ring-plane, giving them finite inclinations.

Stray light within the camera system is responsible for the broad, faint "Y" shape across the image.

A labeled version of this view marks the positions of the moons near the left side of the image.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on March 15, 2006, at a distance of approximately 2.4 million kilometers (1.5 million miles) from Saturn. The image scale on the sky at the distance of Saturn is 142 kilometers (88 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.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: April 25, 2006 (PIA 08163)
Image/Caption Information

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