Tethys Shadow

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Ok I admit, they got me. 

I was looking around and ran across this image of the shadow of the Saturn moon Tethys.  I exclaimed HA!. . . . then I read the caption.  It turns out not to be a goof, and instead is a pretty amazing shot and since it owes to the angle of the rings it occurs at regular intervals but is very uncommon for us to be able to witness such a sight.

The Cassini caption:

The tip of the shadow of the moon Tethys is cut off where it crosses Saturn’s B ring, demonstrating the variations in density across the planet’s rings.

Most of Tethys’ shadow is seen lying across the A ring and Cassini Division in this view which looks toward the unilluminated side of the rings from about 50 degrees above the ringplane. The densest part of the A ring and the denser B ring let neither sunlight nor the darkness of Tethys’ shadow pass through to the spacecraft’s camera, so the moon’s shadow appears cut off. The B ring appears brightly lit here from Saturnshine. Tethys itself is not shown. See Shadow Slipping Through for view of Tethys’ shadow cut off more abruptly by the B ring.

As Saturn approaches its August 2009 equinox, the planet’s moons cast shadows onto the rings. To learn more about this special time and to see a movie of a moon’s shadow moving across the rings, see Moon Shadow in Motion.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on April 29, 2009. The view was acquired at a distance of approximately 1.3 million kilometers (808,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 52 degrees. Image scale is 76 kilometers (47 miles) per pixel.