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Spiral density waves in Saturn's A ring reveal the gravitational signatures of distant moons as they subtly tug on the countless particles orbiting in the ring plane.
A spiral density wave is a spiral-shaped massing of particles that tightly winds many times around the planet. Thus, the wave patterns seen here represent successive windings of each wave, like a closeup view of a watch spring.
Ring scientists can read these patterns, learning from them how quickly the rings are spreading and the amount of mass contained in a region.
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 April 1, 2008. The view was obtained at a distance of approximately 268,000 kilometers (167,000 miles) from Saturn. Image scale is 1 kilometer (0.6 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.