CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Eclipsing Mimas

As the moon Enceladus eclipses its neighbor Mimas, Cassini records a scene possible only around the time of Saturn's approaching equinox.

Seven images, each taken about 30 seconds apart, were combined to create this movie which shows the shadow of Enceladus (504 kilometers, or 313 miles, across) darkening Mimas (396 kilometers, or 246 miles, across). Although Saturn has eclipsed moons in previous images (see PIA11143 and PIA11508), this is the first time Cassini has imaged one of Saturn's moons being eclipsed by another moon rather than the planet. The novel illumination geometry created as the Saturnian system approaches equinox means that during this time moons orbiting in or near the plane of Saturn's equatorial rings can cast shadows onto the rings and onto each other.

To learn more about this special time and to see a movie of a moon's shadow moving across the rings, see PIA 11651.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera on May 13, 2009. The view was obtained at a distance of approximately 1.3 million kilometers (808,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 43 degrees. Image scale is 8 kilometers (5 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: June 22, 2009 (PIA 11661)
Image/Caption Information
  Eclipsing Mimas
PIA 11661

Avg Rating: 8.24/10

Flash 22 KB
Quicktime 45 KB
MP4 movie 27 KB

Alliance Member Comments
mipsandbips (Jun 24, 2009 at 9:00 PM):
Interesting how in the eclipse sequence that immediately after the sequence is over and when restarting that sequence, there is a distinct and noticeable observed rotation in Mimas, even though it is very slight.
Dragon_of_Luck_Mah_Jonng1971 (Jun 23, 2009 at 10:29 AM):
A side note: The part at the top of Mimas seems not to be eclipsed by Enceladus' shadow scarcely.