Tethys' Truncated Shadow
June 3, 2009
The tip of the shadow of the moon Tethys is cut off where it crosses Saturn's B ring, demonstrating the variations in density across the planet's rings.
Most of Tethys' shadow is seen lying across the A ring and Cassini Division in this view which looks toward the unilluminated side of the rings from about 50 degrees above the ringplane. The densest part of the A ring and the denser B ring let neither sunlight nor the darkness of Tethys' shadow pass through to the spacecraft's camera, so the moon's shadow appears cut off. The B ring appears brightly lit here from Saturnshine. Tethys itself is not shown. See Shadow Slipping Through for view of Tethys' shadow cut off more abruptly by the B ring.
As Saturn approaches its August 2009 equinox, the planet's moons cast shadows onto the rings. To learn more about this special time and to see a movie of a moon's shadow moving across the rings, see Moon Shadow in Motion.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on April 29, 2009. The view was acquired at a distance of approximately 1.3 million kilometers (808,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 52 degrees. Image scale is 76 kilometers (47 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 mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
Credit: NASA/JPL/Space Science Institute