Watch Saturn’s Moons Race Inside the Rings

Round and round they go… the animation above, made from 14 raw images taken by NASA’s Cassini spacecraft on August 23, 2016, shows the moons Prometheus and Atlas orbiting Saturn within the Roche Division gap between its A (top right) and F (center) rings. The gravitational tug of Prometheus (92 miles / 148 km long) is strong…

A Visual Demonstration of Gravity, Courtesy of Cassini

Prometheus is at it again! On Feb. 5, Cassini acquired a series of images with its narrow-angle camera of Saturn’s reflective and ropy F ring, around the inside of which travels the shepherd moon Prometheus. As it orbits Saturn it regularly arcs outwards toward the inner edge of the F ring and tumbles back inwards…

Ghosts of Worlds Passed

Saturn’s F ring is a fascinating structure. Made of fine icy particles — most no larger than the particulates found in cigarette smoke — it orbits Saturn just outside the A ring and is easily perturbed by the gravity of nearby moons and embedded moonlets, which create streamers and clumps that rise up in fanciful…

Cassini’s Christmas Gift: a Peek at Prometheus

Captured on Christmas Day, this is a raw image from Cassini showing Saturn’s F ring buckling inwards at two places due to the gravitational tug of its inner shepherd moon, Prometheus, seen at center. As the irregularly-shaped moon approaches the ring material in its looping orbit around Saturn it draws material from the ring in…

Daphnis Is Back!

It’s been a while since I posted an image of my favorite moon of Saturn, but while looking through some recent raw images returned by the Cassini spacecraft I spotted it: Daphnis, the little sculptor shepherd moon!

A Shepherd’s Shadow

Inner shepherd of Saturn’s ropy F-ring, Prometheus casts a long shadow through the ring’s icy haze in this beautifully reworked Cassini image by Gordan Ugarkovic. Discovered by Voyager in 1980 Prometheus completes a tumbling orbit around Saturn every 14.7 hours, regularly dipping into the F-ring in a scalloped path and pulling out streamers of icy…

You say potato, I say Prometheus.

Here’s a nicely processed-and-polished photo of Saturn’s moon Prometheus, fresh from the Cassini imaging center at the Space Science Institute in Boulder, CO. Taken during the spacecraft’s flyby of the F-ring’s shepherd moon earlier this year, this image shows Prometheus’ potato-like shape and heavily cratered surface on its trailing side, dimly illuminated by reflected light…

Prometheus Passing

Prometheus, shepherd moon of Saturn’s F ring, is featured in this dramatic image from Cassini taken as it passed by at a distance of 23,000 miles (37,014 km) on January 27, 2010. This is the closest Cassini has come to Prometheus. The image above has been extensively cleaned up in regard to CCD pixel noise…

A Visit to Prometheus

This raw image, taken by the Cassini spacecraft on December 26, 2009 (on a certain space blogger’s birthday, by the way) shows an amazing view of Prometheus, one of Saturn’s many shepherd moons. This is the closest yet that Cassini has come to the 96-mile-long oblong moon. Details of its cratered surface are visible, as…

A Fresh Perspective

Prometheus’ shadow slices through the strands of Saturn’s F ring in this low-angle view from the Cassini orbiter. The sunlit shepherd moon is a bit overexposed in this image, in order to capture the bands of the rings. This view is looking outwards across the edge of the B ring (at lower left), the darker…

Around the Track

Shepherd moons Prometheus and Daphnis race around Saturn’s rings within their respective gaps, affecting the ring material in their own distinct ways. Prometheus, on the left side, pulls the bright, ropy F ring into streamers while tiny Daphnis, embedded in the 25-mile-wide Keeler gap at lower center, sends up a mound of darker A ring…

Shepherds Passing

  Without as much as a wave shepherd moons Prometheus and Atlas pass by each other, each on their own paths around the rings. Prometheus, casting a long shadow,  pulls at the F ring’s bands of material while smaller Atlas guards the edges of the A ring. The larger is 93 miles across at its…