CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Waves from Daphnis

Undulations mark both sides of the path of Saturn's moon Daphnis through the A ring.

Daphnis may be small at only 8 kilometers (5 miles) across, but the moon's gravity is great enough, and the Keeler gap in which it resides is narrow enough, to perturb the particles in the ring and create the wavelike patterns seen here.

This view looks toward the unilluminated side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 21, 2009. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 50 degrees. Image scale is 7 kilometers (4 miles) per pixel.

The Cassini Equinox Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. 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 Equinox Mission visit, and

Credit: NASA/JPL/Space Science Institute
Released: April 21, 2009 (PIA 11475)
Image/Caption Information
  Waves from Daphnis
PIA 11475

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Alliance Member Comments
CheshireCat (Apr 22, 2009 at 3:16 PM):
mipsandbips: If you're suggesting that Daphnis has been ablated by collisions, that actually seems to be the reverse of what we found in our 2007 paper (Porco et al., 2007 in Science). It looks more like Daphnis grew out of ring material in the A ring. It would be almost impossible to add more material to Daphnis now since tidal and centrifugal forces would tend to pull it off more strongly than gravity would hold it.

Also note that if Daphnis were larger, the gap would also be larger. In fact, the gap edge would probably be too far away for Daphnis to make physical contact. (Think about Pan in the Encke gap.)

But I do like how you think! Collisions have almost certainly done a lot of shape Daphnis!

--- John Weiss, CICLOPS
mipsandbips (Apr 21, 2009 at 7:33 PM):
One might have seen the Keeler gap at one time being much
wider in the A ring; the size and mass of Daphnis being much greater
as its orbit creates constant collisions displaced it's mass into the
Keeler gap making it narrower.