CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Small Moon Shadow

Small Moon Shadow
PIA 11574

Avg Rating: 9/10

Full Size 1020x1020:
PNG 133 KB
  Atlas casts a slender shadow on the A ring as the small moon orbits in the Roche Division between Saturn's A ring and thin F ring.

Atlas (30 kilometers, 19 miles across) is the bright dot in the middle part of the right of the image. The novel illumination geometry created around the time of Saturn's August 2009 equinox allows moons orbiting in or near the plane of Saturn's equatorial rings to cast shadows onto the rings. These scenes are possible only during the few months before and after Saturn's equinox which occurs only once in about 15 Earth years. To learn more about this special time and to see movies of moons' shadows moving across the rings, see PIA11651 and PIA11660.

This view looks toward the unilluminated side of the rings from about 41 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 14, 2009. The view was acquired at a distance of approximately 1.6 million kilometers (994,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 86 degrees. Image scale is 9 kilometers (6 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: September 7, 2009 (PIA 11574)
Image/Caption Information

Alliance Member Comments
mipsandbips (Sep 7, 2009 at 9:26 PM):
When comparing the fine outer edge of the A ring with the inner edge of the F ring that the F ring is alot less clearly defined, although once might consider less dense areas of the F ring a "minor gaps" inside of the F ring. So, if the distance of Atlas to the edge of the A ring is a unit, then 2.5 of that unit would be about the distance of Atlas the the first "minor gap" of the F ring.
stowaway (Sep 7, 2009 at 12:02 PM):
leapin' and hoppin' on a moon shadow