NASA recently published a wonderful image, showing a relatively small Saturnian moon, known as Dione (1,123 km across), passing in front of Titan (5,150 km across), Saturn’s largest moon.

The image was acquired by the Saturn-bound Cassini spacecraft. Titan is characterized by a pale halo, due to its hazy thick atmosphere. 

Saturn has a large system of moons, and this image reveals an example of intriguing mutual dynamical events, observable in the Saturn system. Such phenomena enable astronomers to refine their understanding of the orbits of Saturn's moons. More information are available through the following link:http://photojournal.jpl.nasa.gov/catalog/PIA11692 

The image was taken in visible blue light, with Cassini’s narrow-angle camera, on 12 March 2010. Cassini was at a distance of approximately 2.2 million km from Dione and 3.6  million km from Titan. The image has been contrast-enhanced and magnified by a factor of 1.5, to improve visibility.