Even without color, this is an impressive image: Saturn’s largest moon eclipsing the sun from Cassini’s perspective. The sun is quite small at this distance, so what we see in this image is Titan’s nitrogen atmosphere bending sunlight toward the spacecraft. Note the atmospheric structure at the north pole and that global layer of high haze.
Notice the little speck above the rings and to the left of Titan. That’s the moon Janus, which shares an orbit with Epimetheus. Both were observed from Earth in the late 1960′s, but confusion over observing these faint moons left their actual confirmation up in the air until the Voyager encounters in the early 80′s. It was only then astronomers realized they had been viewing two moons, not one.