Mutual Event in the Space of Saturn: Tethys and Dione

Caption NASA:"From the Cassini Spacecraft's perspective, Saturn's moon Dione passes in front of the moon Tethys in this "Mutual Event".
These 3 images were each taken about one minute apart. These images are part of a Mutual Event Sequence in which one moon passes close to or in front of another. Such observations help scientists refine their understanding of the orbits of Saturn's moons.
Brightly lit Terrain seen here is on the anti-Saturn side of Dione and between the Leading Hemisphere and anti-Saturn side of Tethys. The large Odysseus Crater is visible on Tethys. Tethys is approx.2,6 MKM (about 1,6 MMs) from Cassini. Dione is spprox. 2,2 MKM (such as about 1,4 MMs) away.
Sunlight reflected by Saturn, which is out of the frame to the right, is lighting up the side of Tethys that is away from the Sun, but due to the Spacecraft's viewing angle and the relative positions of each body, this is not true for Dione.

The images were taken in Visible Light with the Cassini pacecraft narrow-angle camera on Nov. 28, 2009. Scale in the original images was roughly 13 Km (a little more than 8 miles) per pixel on Dione and about 16 Km (approx. 10 miles) per pixel on Tethys.
The images were contrast enhanced and magnified by a factor of 1.5 to enhance the visibility of Surface Features on both moons".