Saturn’s Moon Pandora Stripped of ‘Shepherd’ Status2 min read

A decade-long study tracking the intricate motions of Saturn’s ring moons shows that Pandora, located just outside the F Ring, actually is not gravitationally herding the narrow ring’s outer edge.

It, along with partner moon Prometheus, located just the inside the F-ring, actually stir up particles in the rings, but in the midst of the chaos, a stable core exists.

Prometheus (right) and Pandora (left), with Saturn’s F ring in between. Both moons are oddly shaped. Prometheus is 63 miles in diameter, Pandora is 52 miles in diameter. Cassini shot the picture at a distance of about 300,000 miles in October 2005. NASA/JPL/SPACE SCIENCE INSTITUTE

Prometheus (right) and Pandora (left), with Saturn’s F ring in between. Both moons are oddly shaped. Prometheus is 63 miles in diameter, Pandora is 52 miles in diameter. Cassini shot the picture at a distance of about 300,000 miles in October 2005.
NASA/JPL/SPACE SCIENCE INSTITUTE

“The long-term stability of the narrow F Ring core has been hard to understand. Instead of acting as ‘shepherds,’ Prometheus and Pandora together stir the vast preponderance of the region into a chaotic state,” planetary scientist Jeffrey Cuzzi, with NASA’s Ames Research Center in Moffett Field, Calif., writes in a paper published in the April edition of Icarus.

Extrapolating from nearly 10 years worth of data collected by the Saturn-orbiting Cassini spacecraft, Cuzzi and colleagues ran computer simulations showing how complicated orbital dynamics can lead to what they call “calm in the midst of chaos.”

The explanation is quite nuanced, but basically has to do with the difference in timing between the ring particles’ motions and the moons’ orbits. The study showed a neat connection between Prometheus’ orbit and ring particles darting in and out which ends up keeping the ring in balance.

“Essentially, we find that the F Ring core is not confined by a combination of Prometheus and Pandora, but a combination of Prometheus and precession,” the authors write.

Precession is the change in orientation of a spinning body due to gravitational influences.

Source: Discovery News

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Sebastien Clarke

Sebastien Clarke

Astronaut is dedicated to bringing you the latest news, reviews and information from the world of space, entertainment, sci-fi and technology. With videos, images, forums, blogs and more, get involved today & join our community!
Sebastien Clarke
Sebastien Clarke

Astronaut is dedicated to bringing you the latest news, reviews and information from the world of space, entertainment, sci-fi and technology. With videos, images, forums, blogs and more, get involved today & join our community!

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