CICLOPS: Cassini Imaging Central Laboratory for OPerationS
Yin and Yang

Yin and Yang
PIA 17142

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  Iapetus is a moon of extreme contrasts. The light and dark features give the moon a distinctive "yin and yang" appearance. Scientists believe that a runaway migration of ice on the surface, triggered by a preferential initial darkening and consequential warming of the leading hemisphere of the moon by infalling debris from the outer moon Phoebe, may be responsible for the unusual and striking appearance.

For more on Iapetus (914 miles, 1471 kilometers across), see this press release about theories regarding this moon's unique color dichotomy or images of the color dichotomy.

This view looks toward the Saturn-facing hemisphere of Iapetus. North on Iapetus is up and rotated 30 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 30, 2013.

The view was obtained at a distance of approximately 1.5 million miles (2.5 million kilometers) from Iapetus. Image scale is 14 miles (23 kilometers) per pixel. This image has been magnified by a factor of 1.5.

The Cassini Solstice Mission is a joint United States and European endeavor. 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 was designed, developed and assembled at JPL. 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 Solstice Mission visit, and

Credit: NASA/JPL-Caltech/Space Science Institute
Released: December 23, 2013 (PIA 17142)
Image/Caption Information

Alliance Member Comments
NeKto (Dec 28, 2013 at 10:27 PM):
for me, this moon is more fascinating than Enceladus. i understand processes that produce geysers. i can wrap my mind around the process that produces the color dichotomy. it's that equatorial mountain range that really gets me. the leading hypothesis i've seen is sound, but i wonder if there is more to it. i remember Arthur C. Clarke predicting that mountain range. as Carolyn Porco said "How did he know?"