Saturn's moon Epimetheus casts a shadow across colorful rings in thisimage taken before the planet's August 2009 equinox.
Epimetheus (113 kilometers, or 70 miles across) is visible as a small dotat the center of the bottom of the image.
The novel illumination geometry that accompanies equinox lowers the sun'sangle to the ringplane, significantly darkens the rings, and causesout-of-plane structures to look anomalously bright and cast shadows acrossthe rings. These scenes are possible only during the few months before andafter Saturn's equinox, which occurs only once in about 15 Earth years.Before and after equinox, Cassini's cameras have spotted not only thepredictable shadows of some of Saturn's moons (see PIA11657), but also the shadows of newly revealed vertical structures in the ringsthemselves (see PIA11665).
Images taken using red, green and blue spectral filters were combined tocreate this natural color view. This view looks toward the southern,sunlit side of the rings from about 39 degrees below the ringplane.
The images were obtained with the Cassini spacecraft wide-angle camera onJune 8, 2009 at a distance of approximately 725,000 kilometers (450,000miles) from Saturn. Image scale is 40 kilometers (25 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.