Epimetheus

This shot from a few weeks ago is a really nice picture of Epimetheus--the best one ever taken, I think. I missed it in the raw images archive.

As with many small, irregular bodies, you can see what looks like some sort of loose material softening the contours of the moon in the craters and hollows, and rougher material sticking out above that. On asteroids the loose stuff is usually some sort of gravel or dust--as the caption points out, though, here it's probably mostly made of water ice.

Epimetheus orbits just outside of Saturn's main rings and is famous for its peculiar co-orbital relation with Janus. The orbits are so close together that they are separated by less than the moons' widths, but they never collide--instead, every few years the difference in orbital velocities brings them close together, and they gravitationally swap orbits and start to move apart again. It's somewhat similar to the relationship between 3753 Cruithne and Earth, though that situation's more complex, and there the difference in mass means that Cruithne's orbit does most of the changing.

Lakes by radar

The south pole of Titan doesn't have as many methane/ethane lakes as the north pole, probably just because of the seasons—it will be interesting to see if this changes toward northern-hemisphere summer. These pictures are built up of radar swaths imaged by Cassini's big radio dish as it repeatedly flies past Titan on its various orbits around Saturn. All the colors in the pictures are fake; the interpretation is just that dark, smooth areas are probably liquid.