PIA11559: Along the F Ring


Along the F Ring

Caption:

Saturn's moon Janus casts a shadow on the F and A rings while the moon Prometheus, seen on the left of the image, creates a streamer-channel in the thin F ring.

The gravity of potato-shaped Prometheus (86 kilometers,or 53 miles across) periodically creates streamer-channels in the F ring. See PIA10461 and PIA10593 to learn more. To watch a movie of this process, see PIA08397 .

Janus, the moon casting the shadow, is not shown in this image taken as Saturn approaches its August 2009 equinox. Six background stars are visible. They appear elongated by the camera's long exposure time.

The novel illumination geometry that accompanies equinox lowers the sun's angle to the ringplane and causes out-of-plane structures to cast long shadows across the rings. These scenes are possible only during the few months before and after Saturn's equinox, which occurs only once in about 15 Earth years. To learn more about this special time and to see movies of moons' shadows moving across the rings, see PIA11651 and PIA11660 .

This view looks toward the unilluminated side of the rings from about 28 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 20, 2009. The view was acquired at a distance of approximately 1.7 million kilometers (1.1 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 123 degrees. Image scale is 10 kilometers (6 miles) per pixel.

Background Info:

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 .

Cataloging Keywords:

Name Value Additional Values
Target Saturn Rings A Ring, Earth, F Ring, Janus, Prometheus, Saturn, Sun
System Saturn Earth
Target Type Ring Earth, Planet, Satellite, Sun
Mission Cassini-Huygens
Instrument Host Cassini Orbiter
Host Type Orbiter
Instrument Imaging Science Subsystem (ISS)
Detector Narrow Angle Camera
Extra Keywords Grayscale, Shadow
Acquisition Date
Release Date 2009-08-17
Date in Caption 2009-06-20
Image Credit NASA/JPL/Space Science Institute
Source photojournal.jpl.nasa.gov/catalog/PIA11559
Identifier PIA11559