December 8, 2009
From just above the plane of Saturn's rings, the Cassini spacecraft snapped this shot of Saturn two months after Saturn's August 2009 equinox, showing the shadow of its rings as a narrow band on the planet.
Cassini is looking toward the sunlit side of the rings from about 1 degree above the ringplane.
The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and cast shadows across 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. Before and after equinox, Cassini's cameras have spotted not only the predictable shadows of some of Saturn's moons (see Across Resplendent Rings), but also the shadows of newly revealed vertical structures in the rings themselves (see A Small Find Near Equinox).
The image was taken with the Cassini spacecraft wide-angle camera on Oct. 16, 2009 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.5 million kilometers (932,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 83 degrees. Image scale is 86 kilometers (53 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