The presence of the tiny ring moon Daphnis is betrayed by the edge waves it creates in the Keeler gap.
The gap is a narrow lane, about 42 kilometers (26 miles) wide, in Saturn's outer A ring. Daphnis (7 kilometers, or 4.3 miles across) was discovered in Cassini spacecraft images at the same time that scientists spotted the edge waves. Researchers had suspected the presence of a moon in this gap after Pan was discovered in Voyager spacecraft images taken 25 years earlier.
This view looks toward the unilluminated side of the rings from about 54 degrees above the ringplane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 17, 2007 at a distance of approximately 1.8 million kilometers (1.1 million miles) from Saturn. Image scale is 10 kilometers (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 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