* Astronomy

These side-by-side natural colour and false-colour views show cratered terrain on the anti-Saturn hemisphere of Tethys -- the side that always faces away from Saturn. The rim of the immense impact basin of Odysseus (450 kilometres across) lies on the eastern limb, at the 2 o'clock position, making the limb there appear flatter than elsewhere. Other large craters seen here are Penelope (left of centre) and Melanthius (below centre).
The region between Penelope and Odysseus has not previously been imaged at such high resolution before.
The natural colour view was created by compositing images taken using red, green and blue spectral filters.


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Credit NASA

To create the false-colour view, ultraviolet, green and infrared images were combined into a single picture that isolates and maps regional colour differences. This "colour map" was then superimposed over a clear-filter image that preserves the relative brightness across the body. The combination of colour map and brightness image shows how colours vary across the surface of Tethys. The origin of the colour differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy surface material.
North on Tethys is up.
The images were taken with the Cassini spacecraft narrow-angle camera on Dec. 31, 2006 at a distance of approximately 414,000 kilometres from Tethys. Image scale is 2 kilometres per pixel.

This global digital map of Saturn's moon Tethys was created using data taken by the Cassini spacecraft, with gaps in coverage filled in by NASA's Voyager spacecraft data. The map is an equidistant projection and has a scale of 300 meters per pixel. Equidistant projections preserve distances on a body, with some distortion of area and direction.


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Credit: NASA/JPL/Space Science Institute

The mean radius of Tethys used for projection of this map is kilometres.
This map is an update to the version released in December 2005.

Tethys has a crater-saturated surface, where older, larger basins have been completely overprinted by newer, smaller impacts. This state is what scientists expect to see on a very old surface, where small impactors have struck more frequently than larger ones over several billion years. Larger impacts were more common events in the early history of the solar system.


Credit NASA/JPL/Space Science Institute

This view looks toward the leading hemisphere of Tethys. North is up. The great scar of Ithaca Chasma is seen at right.
The view was captured in visible light with the Cassini spacecraft narrow-angle camera on Sept. 25, 2006 at a distance of approximately 449,000 kilometres from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 49 degrees. Image scale is 3 kilometres per pixel.

This image of Tethys was taken by the Cassini spacecraft on September 09, 2006, when it was approximately 221,633 kilometres away.


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Credit NASA

The image was taken using the P60 and UV3 filters.