Phoebe orbits Saturn at a distance of about 13 million kilometres and is the most distant of the planet's main moons. Cassini's fly-by in June 2004 revealed an icy surface pitted with deep craters that were created by violent surface impacts. Such impacts may have ejected material that later formed some of the 12 tiny outer moons discovered orbiting Saturn in 2000.

Phoebe is only 220 kilometres across, and may be a comet-like object captured in Saturn's gravity. This may explain why Phoebe was, until 2000, the only known Saturnian satellite with a retrograde orbit, that is, the directions in which Phoebe orbits Saturn and Saturn orbits the Sun are opposed. Phoebe was discovered by astronomer William Henry Pickering in 1898.