The moon Tethys casts its shadow on Saturn's rings next to the shadow of the planet in this image taken as Saturn approaches its August 2009 equinox.
Tethys and Saturn are off to the left of this image and are not shown. The largest of the bright specks in the image is Pandora (81 kilometers, or 50 miles across). Other bright spots are background stars.
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 .
This view looks toward the unilluminated side of the rings from about 51 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 28, 2009. The view was acquired at a distance of approximately 1.5 million kilometers (932,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 78 degrees. Image scale is 88 kilometers (55 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