Planetshine

The phenomenon known as planetshine occurs when reflected sunlight from a planet illuminates the night side of one of its moons. Typically, this results in the moon's night side being bathed in a soft, faint light. The best known example of planetshine is earthshine, which can be seen from Earth when the Moon is a thin crescent. Planetshine has been observed elsewhere in the solar system: in particular, it has recently been used by the Cassini space probe to image portions of the moons of Saturn even when they are not lit by the Sun.