Tuesday, May 18, 2010

Daphnis Hidden Among Waves

Saturn's moon Daphnis, appearing as a tiny speck in the Keeler Gap of the A ring on the far right of this Cassini spacecraft image, is almost lost among the moon's attendant edge waves.

Daphnis (8 kilometers, or 5 miles across) has an inclined orbit relative to the ringplane. Its gravitational pull perturbs the orbits of the particles of the A ring forming the Keeler Gap's edge and 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.

The Encke Gap of the A ring, wider than the Keeler Gap, can be seen passing through the middle of the image. Several background stars are also visible. This view looks toward the southern, unilluminated side of the rings from about 16 degrees below the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 7, 2010. The view was acquired at a distance of approximately 1.7 million kilometers (1.1 million miles) from Saturn. Image scale is 10 kilometers (6 miles) per pixel.

Photo credit: NASA/JPL/Space Science Institute

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