Saturday, July 31, 2010

Daphnis and the Rings


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

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