CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Shadows Still Seen

Shadows Still Seen
PIA 11612

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  About a month after Saturn's August 2009 equinox, shadows continue to grace the planet's rings.

Pan (28 kilometers, 17 miles across) orbits in the Encke Gap which runs through the center of the image. The small moon can be seen casting a faint, narrow shadow on the A ring above and to the right of the center of the image.

On the far left of the image, a small vertical structure in the thin F ring can be seen casting a shadow on the ring.

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 PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

Janus (179 kilometers, 111 miles across) can be seen in the bottom right of the image. Bright specks in the image are stars.

This view looks toward the northern, sunlit side of the rings from about 6 degrees above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 13, 2009. The view was obtained at a distance of approximately 2.6 million kilometers (1.6 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 117 degrees. Image scale is 15 kilometers (9 miles) per pixel.

The Cassini Equinox Mission is a joint United States and European endeavor. 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 was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini Equinox Mission visit, and

Credit: NASA/JPL/Space Science Institute
Released: October 29, 2009 (PIA 11612)
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