August 11, 2009
The shadow of the moon Tethys cuts across the C ring in this image taken as Saturn approaches its August 2009 equinox.
The novel illumination geometry created as Saturn approaches its 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 Moon Shadow in Motion and Weaving a Shadow.
Saturn, although very faint, can be seen lit by ringshine on the right of the image. Stars can be seen through the rings and in the background.
This view looks toward the sunlit side of the rings from about 36 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 9, 2009. The view was obtained at a distance of approximately 578,000 kilometers (359,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 66 degrees. Image scale is 31 kilometers (19 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