Arc On-Edge

Seen from a viewpoint nearly coincident with the ringplane, the bright arc within the G ring appears even brighter with its ring material concentrated in the center of this image.

This partial arc is much narrower than the ring and extends only one-sixth of the way around the G ring. The arc is 250 kilometers (150-miles) wide and extends 150,000 kilometers (93,000 miles) in orbital longitude. The collection of particles that make up the arc is held in place by a resonance, or gravitational disturbance, from the moon Mimas.

The motion of the spacecraft smeared background stars into streaks because the camera needed a very long exposure time of 26 seconds to capture light reflected from the faint ring. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 28, 2009. This view looks toward the sunlit side of the rings from just barely below the ringplane.

The view was acquired at a distance of approximately 1.2 million kilometers (750,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 27 degrees. Image scale is 7 kilometers (4 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 .

Credit: NASA/JPL/Space Science Institute