F-Ring Perturbations

The F ring shows off a rich variety of phenomena in this image from the Cassini spacecraft. Near the lower-right of the F ring are two "fans" of material radiating out of the main strand (or "core") of the ring. Kinks are apparent all along the core, and dark "channels" cut into the main strand can be seen in places, the result of a recent interaction with the shepherd moon Prometheus (which cannot be seen in this image).

Scientists believe that many of the F ring's diverse features are the result of interactions between ring material and either the shepherd moons or clumps of material within the ring.

This view looks toward the sunlit side of the rings from about six degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on December 25, 2012.

The view was acquired at a distance of approximately 680,000 miles (1.1 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 17 degrees. Image scale is 4 miles (6 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

F-Ring Fan

The Cassini spacecraft spies a "fan" in Saturn's tenuous F ring.

This fan-like structure appears as dark lines spreading outward from the left of the bright clump of ring material near the center of the image. See PIA12784 and PIA12786 to learn more about fans.

This view looks toward the northern, sunlit side of the rings from about 10 degrees above the ringplane. Several background stars are visible, including two that can be seen through the ring.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 1, 2010. The view was acquired at a distance of approximately 1.3 million kilometers (808,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 119 degrees. Image scale is 7 kilometers (4 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Fan Structures in Saturn's F-Ring

Bright clumps of ring material and a fan-like structure appear near the core of Saturn's tenuous F ring in this mosaic of images from NASA's Cassini spacecraft. Such features suggest the existence of additional objects in the F ring.

These discontinuous clumps near the core of the F ring may be created by the passage of the ring's shepherding moon Prometheus, and they can be seen casting narrow shadows that extend toward the bottom of the mosaic. The shadows are marked with arrows in the annotated version. On the right of the mosaic, a "fan" can be seen dissipating above the bright ring core. The fan (marked "F" in the annotated version) is a series of channels within the F ring's particles that appear to have a common origin but that spread outward radially in different directions. Gravitational perturbations on the ring material by a moonlet or clump of material can create these fans. The moonlet or clump orbits more or less elliptically compared to the rest of the F ring can create these fans. It is probably embedded in the ring and is causing the base of the fan channels to meet. See PIA1285 and PIA12786 for similar observations of such fans.

The diagonal streamer-channels are periodically created by the gravity of the potato-shaped moon Prometheus which is 148 kilometers (92 miles) on its longest side but is on average 86 kilometers (53 miles) across. To learn more and to watch a movie of this streamer-channel phenomenon, see PIA08397.

The images have been re-projected in this mosaic so that the F ring appears straightened rather than curved and compressed azimuthally (along the ring). This change represents a scale compression in the horizontal direction of about 33 to one which is why Prometheus looks like a bright line. Prometheus is marked "Pr" in the annotated version.

This sequence of 42 images was taken over a span of one hour, seven minutes. The earliest image is on the right, and time progresses moving left in the mosaic. Each image was cropped, re-projected and placed side by side in this montage. Scale in the original images was about 3 kilometers (2 miles) per pixel. The images were contrast enhanced and re-projected to a scale of 33 kilometers (21 miles) per pixel in the mosaic's horizontal direction and one kilometer (0.6 miles) per pixel in the mosaic's vertical direction. The single, cropped inset of the clumps included here was then magnified by a factor of two.

The view in the original images looked toward the northern, unilluminated side of the rings from about 70 degrees above the ring plane.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera on December 8, 2008. The view was obtained at a range of distances from approximately 597,000 kilometers (371,000 miles) to 615,000 kilometers (382,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 77 degrees.

Photo credit: NASA/JPL/Space Science Institute

Notes: For other pictures and information in this series, see the following: PIA12784: Multiple F-Ring "Fans", PIA12786: "Fan" in the F Ring, and PIA12787: The Effect of Prometheus on the F Ring, the last of which includes a very interesting (but high memory-consuming) animation.