CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Obscure Moon

Obscure Moon
PIA 09795

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  Just before Rhea slipped behind Saturn, Cassini captured the moon in its disappearing act.

Along with the partly obscured Rhea (1,528 kilometers, 949 miles across) are Tethys (1,062 kilometers, 660 miles across), at right, and Enceladus (504 kilometers, 313 miles across), left of Tethys.

At the wavelength in which this image was taken, absorption of sunlight by methane gas in Saturn's atmosphere is strong, causing the planet to appear dark.

This view looks toward the unilluminated side of the rings from about 4 degrees above the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on Nov. 9, 2007 using a spectral filter sensitive to wavelengths of infrared light centered at 890 nanometers. The view was acquired at a distance of approximately 2.8 million kilometers (1.7 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 44 degrees. Image scale is 162 kilometers (101 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: December 21, 2007 (PIA 09795)
Image/Caption Information

Alliance Member Comments
carolyn (CICLOPS) (Dec 23, 2007 at 11:18 AM):
Yes, Red_dragon, I agree. The relative appearance of the north and south hemispheres in the methane filters, compared to the visible part of the spectrum, is very intriguing. The imaging team is presently studying this very effect. - Carolyn
Red_dragon (Dec 21, 2007 at 7:57 AM):
I really like the alien -and, especially, dark- look Saturn has through the methane filter. Curious, by the way, how both hemispheres look so similar in aspect, unlike the true color images.