Pan is the innermost moon of Saturn that has been given a name. It’s walnut-shaped, approximately 35 km across and 23 km wide. It’s orbit is in the Encke Gap of Saturn’s A Ring. Pan is one of the rings’ shepherd moon, and it sweeps the Encke Gap free of ring particles.
Nope, but at first glance, Saturn’s rings seem to be intersecting themselves in an impossible way. This view from the Cassini spacecraft shows the rings in front of the planet and the shadows of the rings on the planets clouds. Because rings like the A ring and Cassini Division are not entirely opaque, those shadows can be seen through the rings themselves. If you look closely, you can spot the moon Pan near image’s center. Pan orbits in a space call the Encke Gap and keeps that band essentially clear.
Saturn’s moon Pan, named for the Greek god of shepherds, rules over quite a different domain—the Encke gap in Saturn’s rings. See the inset at left for a zoomed in view. Pan (28 km 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 Christmas Day, 2013, from a distance of approximately 2.3 million km from Pan. The image scale is about 14 km) per pixel.
Saturns rings are divided into distinct bands. The Saturnian moons Prometheus and Pan are both caught “shepherding” their respective rings in this image (click the image to embiggen it). Through their gravitational effect on nearby ring particles, one moon maintains a gap in the outer A ring, and the other helps keep another ring narrowly confined.
Prometheus (86 km across) and its partner Pandora (not seen here), maintains the narrow F ring seen at the bottom left in this image. Pan (28 km across) clears the Encke gap in as it moves along the gap’s center. The other bright dot near the inner edge of the Encke gap is a star in the background.
The large moon in the background is Titan, Saturn’s largest moon. The moon in the foreground is Dione with some of its surface features visible. The small moon to the right of rings is Pandora. There’s a fourth moon in the picture. Look closely at the dark gap in the rings. The tiny speck is the moon Pan.