Saturn's innermost moon Pan orbits the giant planet seemingly alone in a ring gap its own gravity creates.
Pan (17 miles, or 28 kilometers across) maintains the Encke Gap in Saturn's A ring by gravitationally nudging the ring particles back into the rings when they stray in the gap. Scientists think similar processes might be at work as forming planets clear gaps in the circumstellar disks from which they form.
This view looks toward the sunlit side of the rings from about 38 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 3, 2014.
The view was acquired at a distance of approximately 2 million miles (3.2 million kilometers) from Pan and at a Sun-Pan-spacecraft, or phase, angle of 56 degrees. Image scale is 12 miles (19 kilometers) per pixel.
Image credit: NASA/JPL-Caltech/Space Science Institute
Although it appears empty from a distance, the Encke gap in Saturn's A ring has three ringlets threaded through it, two of which are visible here.
Each ringlet has dynamical structure such as the clumps seen in this image. The clumps move about and even appear and disappear, in part due to the gravitational effects of Pan.
This view looks toward the sunlit side of the rings from about 27 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 11, 2013.
The view was obtained at a distance of approximately 199,000 miles (321,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 121 degrees. Image scale is 1 mile (2 kilometers) per pixel.
Image credit: NASA/JPL-Caltech/Space Science Institute
Saturn's moon Pan, named for the Greek god of shepherds, rules over quite a different domain: the Encke gap in Saturn's rings.
Pan (17 miles, or 28 kilometers across) keeps the Encke gap open through its gravitational influence on the ring particles nearby.
This view looks toward the sunlit side of the rings from about 48 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on December 25, 2013.
The view was obtained at a distance of approximately 1.4 million miles (2.3 million kilometers) from Pan and at a Sun-Pan-spacecraft, or phase, angle of 87 degrees. Image scale is 9 miles (14 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
Although their gravitational effects on nearby ring material look quite different, Prometheus and Pan -- pictured here -- are both shepherd moons, holding back nearby ring edges.
Pan (17 miles,or 28 kilometers across), near the right edge of the image, holds open the Encke gap that it orbits in. Prometheus (53 miles, or 86 kilometers across), near the upper left, helps shape the F ring and maintain its narrow form.
This view looks toward the unilluminated side of the rings from about 47 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 27, 2013.
The view was acquired at a distance of approximately 870,000 miles (1.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 81 degrees. Image scale is 5 miles (8 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
The shepherd moon Pan orbits Saturn in the Encke gap while the A ring surrounding the gap displays wave features created by interactions between the ring particles and Saturnian moons.
Pan (17 miles, or 28 kilometers across) maintains the Encke gap through gravitational interactions with ring particles. The wave features in the A ring are generated through interactions between ring particles and moons such as Pan.
This view looks toward the sunlit side of the rings from about 34 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 11, 2013.
The view was obtained at a distance of approximately 240,000 miles (386,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 111 degrees. Image scale is 1 mile (2 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
The ring-region Saturnian moons Prometheus and Pan are both caught "herding" their respective rings in this image. Through their gravitational disturbances of nearby ring particles, one moon maintains a gap in the outer A ring and the other helps keep a ring narrowly confined.
Prometheus (53 miles, or 86 kilometers across), together with Pandora (not seen in this image), maintains the narrow F ring seen at the bottom left in this image. Pan (17 miles, or 28 kilometers across) holds open the Encke gap in which it finds itself embedded in the center. The bright dot near the inner edge of the Encke gap is a background star.
This view looks toward the unilluminated side of the rings from about 29 degrees below the ringplane. The image was taken in visible violet light with the Cassini spacecraft narrow-angle camera on September 18, 2012.
The view was acquired at a distance of approximately 1.4 million miles (2.3 million kilometers) from Pan and at a Sun-Pan-spacecraft, or phase, angle of 98 degrees. Image scale is 9 miles (14 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
Saturn's tiny moon Pan orbits in the middle of the Encke Gap of the planet's A ring in this image from the Cassini spacecraft.
Pan (17 miles, or 28 kilometers across) is visible as a bright dot in the gap near the center of this view. See PIA12604 to see Pan casting a long shadow around the time of Saturn's August 2009 equinox.
The wide Roche Division separates the A ring from the thin F ring in the lower left quarter of the view. This view looks toward the southern, unilluminated side of the rings from about 20 degrees below the ringplane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 25, 2012. The view was obtained at a distance of approximately 1.2 million miles (2 million kilometers) from Pan. Image scale is 7 miles (12 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
NASA's Cassini spacecraft has recently resumed the kind of orbits that allow for spectacular views of Saturn's rings. This view, from Cassini's imaging camera, shows the outer A ring and the F ring. The wide gap in the image is the Encke Gap, where you see not only the embedded moon Pan but also several kinky, dusty ringlets. A wavy pattern on the inner edge of the Encke gap downstream from Pan and aspiral pattern moving inwards from that edge show Pan's gravitational influence. The narrow gap close to the outer edge is the Keeler gap.
Photo credit: NASA/JPL-Caltech/SSI
Saturn's moons Daphnis and Pan demonstrate their effects on the planet's rings in this view from the Cassini spacecraft.
Daphnis (5 miles, or 8 kilometers across), on the left of the image, orbits in the Keeler Gap of the A ring. The moon's gravitational pull perturbs the orbits of the particles of the A ring forming the gap's edge and sculpts the edge into waves that move both in the ring's plane (radially) and out of the ring's plane. See PIA11655 and PIA12698 to learn more.
Pan (17 miles, or 28 kilometers across), in the top right of the image, orbits in the Encke Gap of the A ring. The effects of that moon's gravity can be seen as dark wakes on the parts of the rings below Pan in the image, propagating towards the middle of the image. See PIA07528 and PIA10529 to learn more.
This view looks toward the southern, unilluminated side of the rings from about 6 degrees below the ringplane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 3, 2010. The view was obtained at a distance of approximately 329,000 miles (529,000 kilometers) from Saturn. Image scale is 2 miles (3 kilometers) per pixel.
Photo credit: NASA/JPL-Caltech/Space Science Institute
A quartet of Saturn's moons, from tiny to huge, surround and are embedded within the planet's rings in this Cassini composition.
Saturn's largest moon, Titan, is in the background of the image, and the moon's north polar hood is clearly visible. See PIA08137 to learn more about that feature on Titan (3,200 miles, or 5,150 kilometers across). Next, the wispy terrain on the trailing hemisphere of Dione (698 miles, or 1,123 kilometers across) can be seen on that moon which appears just above the rings at the center of the image. See PIA10560 and PIA06163 to learn more about Dione's wisps. Saturn's small moon Pandora (50 miles, or 81 kilometers across) orbits beyond the rings on the right of the image. Finally, Pan (17 miles, or 28 kilometers across) can be seen in the Encke Gap of the A ring on the left of the image.
This view looks toward the northern, sunlit side of the rings from just above the ringplane.
The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on September 17, 2011. The view was obtained at a distance of approximately 1.3 million miles (2.1 million kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 27 degrees. Image scale is 8 miles (13 kilometers) per pixel on Dione.
Photo credit: NASA/JPL-Caltech/Space Science Institute
Six of Saturn's moons orbiting within and beyond the planet's rings are collected in this Cassini spacecraft image.
Enceladus (504 kilometers, or 313 miles across) is the largest moon in this image and appears at the bottom. Janus (179 kilometers, or 111 miles across) orbits beyond the rings near the center of the image. Epimetheus (113 kilometers, or 70 miles across) orbits beyond the rings near the top of the image. Atlas (30 kilometers, or 19 miles across) appears as a tiny speck between the main rings and the thin F ring on the right. Daphnis (8 kilometers, or 5 miles across), which orbits in the narrow Keeler Gap of the A ring, appears as a small, bright speck on the left of the image. Pan (28 kilometers, or 17 miles across), which orbits in the Encke Gap of the A ring, also appears as a bright speck on the left of the image. Daphnis is farther to the left of the image than Pan.
Although Enceladus appears to be in the foreground here, that moon, at a distance of 3.1 million kilometers (1.9 million miles), is actually farthest away from Cassini in this image. Janus is 3 million kilometers (1.9 million miles) from the spacecraft. The view was obtained at a distance of approximately 2.8 million kilometers (1.7 million miles) from Epimetheus.
The rings lie between Janus and Epimetheus. This view looks toward the southern, unilluminated side of the rings from about 2 degrees below the ringplane.
Enceladus is a very reflective body. To enhance visibility, the other moons and the rings have been brightened by a factor of 3.4 relative to Enceladus.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 6, 2010. Image scale is approximately 19 kilometers (12 miles) per pixel on Enceladus, about 18 kilometers (11 miles) per pixel on Janus and about 17 kilometers (11 miles) per pixel on Epimetheus.
Photo credit: NASA/JPL/Space Science Institute
Saturn's small, ring-embedded moon Pan, on the extreme right of this Cassini spacecraft image, can be seen interacting with the ringlets that share the Encke Gap of the A ring with this moon.
Pan is 28 kilometers, or 17 miles, across. This view looks toward the northern, sunlit side of the rings from about 11 degrees above the ringplane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 2, 2010. The view was acquired at a distance of approximately 875,000 kilometers (544,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 130 degrees. Image scale is 5 kilometers (3 miles) per pixel.
Photo credit: NASA/JPL/Space Science Institute
Rather than being an unchanging disk of peaceful particles, the material that makes up Saturn's rings is constantly pushed and pulled into spectacular shapes.
On the left of the image, the moon Daphnis (8 kilometers,or 5 miles across) affects material as it orbits in the A ring's Keeler Gap. The moon's orbit is inclined relative to the plane of Saturn's rings. Daphnis' gravitational pull perturbs the orbits of the particles forming the Keeler Gap's edge. This sculpts the edge into waves having both horizontal (radial) and out-of-plane components. Material on the inner edge of the gap orbits faster than the moon so that the waves there lead the moon in its orbit. Material on the outer edge moves slower than the moon, so waves there trail the moon. See PIA11656 to learn more about this process.
On the right, the material at the edge of the Encke Gap shows waves caused by Pan (28 kilometers, or 17 miles across). See PIA09881 for a similar view.
This view looks toward the southern, unilluminated side of the rings from about 6 degrees below the ringplane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 3, 2010. The view was acquired at a distance of approximately 531,000 kilometers (330,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 33 degrees. Image scale is 3 kilometers (2 miles) per pixel.
Photo credit: NASA/JPL/Space Science Institute
