When the Cassini spacecraft arrived at Saturn almost 14 years ago, its first target was Phoebe, a moon that’s millions of miles from Saturn. Cassini’s pictures revealed an object that’s taken a beating over the eons. It’s been hit by so many big space rocks that it’s no longer round — it has an irregular shape because chunks of its surface have been blasted into space.
Phoebe may not have been born with Saturn. Instead, it might have formed in the Kuiper Belt — a vast ring of rocky and icy bodies beyond the realm of the planets. An encounter with another object kicked it out of the Kuiper Belt. It moved toward the Sun, and was captured by Saturn.