This close pairing of Saturn's moons Janus and Epimetheus shows the two
moons at "high phase," meaning that only a thin sliver of sunlit terrain
is visible on each moon. Portions of each are also lit feebly by reflected
light from Saturn. In this Cassini image, Janus is at top and Epimetheus
is below.
http://spaceflightnow.com/cassini/060214duo.html
From spcae flight now