Which moon is Saturn's largest irregular satellite?

Phoebe is Saturn’s largest irregular satellite.

Unlike Saturn’s major regular moons, Phoebe follows a distant, highly inclined and retrograde orbit, meaning it travels around Saturn in the opposite direction from the planet’s rotation and most regular satellites. Its unusual orbit is why it is classified as irregular, not because of an especially strange shape.

Phoebe was discovered in 1899 by William Henry Pickering from photographic plates made at the Boyden Station in Peru. It was the first moon discovered photographically. The Cassini spacecraft flew past Phoebe in 2004, revealing a dark, heavily cratered world with abundant ice beneath its surface.

A common mix-up is Hyperion, which is also an unusual Saturnian moon, but it is a regular satellite with a chaotic rotation. Telesto and Janus are small inner moons. Phoebe’s composition and orbit suggest that it may be a captured centaur from the outer Solar System.