CICLOPS: Cassini Imaging Central Laboratory for OPerationS
The Colors of Tethys II

The Colors of Tethys II
PIA 19638

Avg Rating: 10/10

Standard Full Size 4000x4000:
PNG 17.4 MB
TIFF 31.0 MB

Quarter Size 1000x1000:
PNG 1.3 MB


The Colors of Tethys II
PIA 19638

Avg Rating: 9.55/10

Enhanced Full Size 4000x4000:
PNG 22.9 MB
TIFF 34.7 MB

Quarter Size 1000x1000:
PNG 1.6 MB
  This enhanced-color mosaic of Saturn's icy moon Tethys shows a range of features on the moon's trailing hemisphere. Tethys is tidally locked to Saturn, so the trailing hemisphere is the side of the moon that always faces opposite its direction of motion as it orbits the planet.

This view was obtained about two and a half hours earlier than PIA19636 and shows terrain slightly farther to the west and south of that view.

Two versions of the mosaic are presented here: one with standard image processing, and one that strongly enhances the relief of craters and other surface features.

Images taken using clear, green, infrared and ultraviolet spectral filters were combined to create the view, which highlights subtle color differences across Tethys' surface at wavelengths not visible to human eyes. The moon's surface is fairly uniform in natural color.

The color of the surface can be seen to change across the disk, from yellowish hues to nearly white. These broad color changes are affected by a number of external processes. First, Saturn's diffuse E-ring preferentially bombards Tethys' leading hemisphere, toward the right side in this image, with ice bright ice grains. At the same time, charged particles from Saturn's radiation belt bombard the surface on the trailing side, causing color changes due to chemical alteration of the materials there. The albedo -- a measure of the surface's reflectivity -- drops by 10 to 15 percent from the moon's leading side to the trailing side. Similar global color patterns exist on other Saturnian moons.

On a much smaller scale, enigmatic, arc-shaped reddish streaks are faintly visible across the heavily-cratered surface, particularly in the upper right quarter of the image (see PIA19637 for a close-up view of these features). The origin of this localized color contrast is not yet understood.

This mosaic is an orthographic projection constructed from 52 Cassini images obtained on April 11, 2015 with the Cassini spacecraft narrow-angle camera. Image scale is about 1,000 feet (300 meters) per pixel. The images were obtained at a distance of approximately 33,000 miles (53,000 kilometers) from Tethys.

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/SSI
Released: July 29, 2015 (PIA 19638)
Image/Caption Information

Alliance Member Comments
Robert (Aug 3, 2015 at 3:36 PM):
Wow! The enhanced full-sized version is incredible for its detail and resolution! And the smoothness of the mosaic is amazing!