CICLOPS: Cassini Imaging Central Laboratory for OPerationS
What's That Speck?

What's That Speck?
PIA 07520

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  Cassini's climb to progressively higher elevations reveals the "negative" side of Saturn's rings. As the Sun shines through the rings, they take on the appearance a photonegative: the dense B ring (at center) blocks much of the incoming light, while the less dense regions scatter and transmit light.

Close inspection reveals not one, but two moons in this scene. Mimas (396 kilometers, 246 miles across) is easily visible near upper right, but the shepherd moon Prometheus (86 kilometers, 53 miles across) can also be seen: it is a dark spot against the far side of the thin, bright F ring. Most of Prometheus' sunlit side is turned away from Cassini in this view.

The image was taken in visible light with the wide angle camera on April 15, 2005, from a distance of approximately 570,000 kilometers (350,000 miles) from Saturn. The image scale is 30 kilometers (19 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 Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. 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-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: June 14, 2005 (PIA 07520)
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