CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Crooked Shadow

The shadow of the moon Mimas strikes the F ring at a different angle than the angle at which it is cast on the A ring, illustrating differences in the vertical heights of the rings in this image taken as Saturn approaches its August 2009 equinox.

The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane and causes out-of-plane structures to cast long shadows across 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.

Pan (28 kilometers, 17 miles across) orbits in the Encke Gap and is visible on the left of the image. The brightness in the lower left of the image is lens flare, a radially extending artifact that results from light being scattered within the camera optics. The shadow of Saturn cuts across the lower right of the image. Two stars can be seen through the rings. Other bright spots in this image are also background stars.

This view looks toward the unilluminated side of the rings from about 52 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 15, 2009. The view was obtained at a distance of approximately 1.8 million kilometers (1.1 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 90 degrees. Image scale is 103 kilometers (64 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: July 28, 2009 (PIA 11545)
Image/Caption Information
  Crooked Shadow
PIA 11545

Avg Rating: 9.62/10

Full Size 1017x655:
PNG 184 KB

Alliance Member Comments
mipsandbips (Jul 29, 2009 at 8:19 PM):
It appears as though the shadow cast onto the A ring
casts a secondary shadow back onto the F ring where it
expands after narrowing towards the middle.
Red_dragon (Jul 28, 2009 at 8:00 AM):
One of the best shadow images you've released.