As Saturn approaches its August 2009 equinox, a shadow is cast by a
narrow, vertically extended feature in the F ring.
Scientists are working to understand the origin of structures such as this
one, but they think this image may show the shadow of an object on an
inclined orbit which has punched through the F ring and dragged material
along in its path.
The second (bottom) version of the image has been brightened to enhance
the visibility of the ring and shadow. Background stars appear elongated
in the image because of the camera's exposure time.
This image and others like it (see PIA11663) are only possible around the
time of Saturn's equinox which occurs every half-Saturn-year (equivalent
to about 15 Earth years). The illumination geometry that accompanies
equinox lowers the sun's angle to the ring plane and causes out-of-plane
structures to cast long shadows across the rings. Cassini's cameras have
spotted not only the predictable shadows of some of Saturn's moons (see
PIA11657), but also the shadows of newly revealed vertical structures in the
rings themselves (see PIA11654).
This view looks toward the unilluminated side of the rings from about 27
degrees above the ring plane.
The image was taken in visible light with the Cassini spacecraft
narrow-angle camera on June 11, 2009. The view was acquired at a distance
of approximately 866,000 kilometers (538,000 miles) from Saturn and at a
Sun-Saturn-spacecraft, or phase, angle of 30 degrees. Image scale is 5
kilometers (3 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.