AGU: Geophysical Research Letters

 

Editors' Highlight

Density and gravity variations within Saturn's A ring

Images from Earth-based observatories and the Voyager spacecraft's pass near Saturn in the early 1980s showed that the brightness of the A ring varies around the ring, with two bright patches separated by two darker patches. These were attributed to density alignments within the orbiting matter of these rings; if ring mass density is large enough, particles can agglomerate for brief amounts of time before they are torn apart by rotational forces and the gravitational pull of Saturn. Colwell et al. (2006) termed these gravitational instabilities "self-gravity wakes" and confirmed their presence through analyzing the patterns of light transmission and interruption as viewed by the Cassini spacecraft as it traveled between Saturn's rings. They also calculated the shape and spacing of the self-gravity wakes using a model and found that they were highly flattened structures with thickness, frequency, and opacity dependent on the radial distance from Saturn. The authors expect that future data from Cassini will help refine their results.

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