CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Diagnostic Darkness

Diagnostic Darkness
PIA 07578

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  This magnificent view looks down upon, and partially through, Saturn's rings from their unlit side.

The densest part of the rings occult the bright globe of Saturn. Scientists can use observations like this to precisely determine the concentration of ring particles.

When the bright source is the signals coming from the spacecraft, the technique is called a 'radio occultation'. In a radio occultation measurement, a signal is beamed toward Earth from Cassini's 4-meter (13-foot) wide high gain antenna. Researchers on Earth receive the signal as the spacecraft passes behind the rings. The amount by which Cassini's radio signal is extinguished tells researchers how densely packed the ring particles are. Scientists can also learn about the size distributions of the particles from occultations.

As an added (but tiny) bonus, Atlas (30 kilometers, 19 miles across) is visible as a dark speck against the planet, just outside the A ring.

The image was taken in visible red light with the wide angle camera on August 2, 2005, from a distance of approximately 617,000 kilometers (383,000 miles) from Saturn. The image scale is 37 kilometers (23 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: September 2, 2005 (PIA 07578)
Image/Caption Information

Alliance Member Comments
Red_dragon (Jan 22, 2008 at 6:39 AM):
Fantastic image, as usual.