The shadow of the moon Epimetheus stretches across the B ring in this image taken by Cassini as Saturn approaches its 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.
This view looks toward the sunlit side of the rings from about 42 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 8, 2009. The view was obtained at a distance of approximately 700,000 kilometers (435,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 129 degrees. Image scale is 4 kilometers (2 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