Tethys appears here, against a background of star trails, in a view
acquired as the icy moon exited Saturn's shadow. Tethys is illuminated in
this view by two main sources: reflected "ringshine" and refracted
sunlight passing through the edge of Saturn's atmosphere.
An observer viewing Saturn from the moon's surface would see the planet's
southern hemisphere aglow with dimly reflected sunlight bouncing off the
rings, called ringshine. They would also witness the beginning of an
orbital sunrise.
The Cassini spacecraft shared a similar perspective when it acquired the
images for PIA08329 (the principal
difference being that Tethys is nearly in the ringplane and Cassini was 15
degrees above the ringplane when it acquired the images for the color
mosaic.)
A long exposure time was required in order to image Tethys while it was in
shadow, resulting in the stars' normally point-like images being smeared
into streaks.
The view looks toward the northern hemisphere of Tethys (1,062 kilometers,
or 660 miles across) from 36 degrees above the moon's equator. The image
was taken in visible light with the Cassini spacecraft wide-angle camera
on June 30, 2008. The view was acquired at a distance of approximately
263,000 kilometers (163,000 miles) from Tethys and at a
Sun-Tethys-spacecraft, or phase, angle of 52 degrees. Image scale is 16
kilometers (10 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 mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov/. The Cassini imaging team
homepage is at http://ciclops.org.
