Phoebe S009

Semimajor Axis: 12.929.400 km


Phoebe is the most massive irregular satellite of Saturn with a mean diameter of 213 km. Phoebe was the first target encountered upon the arrival of the Cassini spacecraft in the Saturn system in 2004, and is thus unusually well-studied for an irregular moon of its size. Cassini's trajectory to Saturn and time of arrival were chosen to permit this flyby. Phoebe has a moderately eccentric, retrograde orbit, making it part of Saturn's Norse group of satellites. It is the second-largest retrograde satellite in the Solar System after Triton. Phoebe is roughly spherical and has a differentiated interior. It was spherical and hot early in its history and was battered out of roundness by repeated impacts. There is some evidence that it may be a captured centaur that originated in the Kuiper belt.