Rhea

Saturn's moons · icy worlds · space exploration

Saturn's second moon. Rhea is the second-largest moon orbiting Saturn and the ninth-largest moon in the entire Solar System. It's about 949 miles wide, which makes it a truly massive world of ice and rock.

Frozen and ancient. Rhea is so small and far from the sun that it's incredibly cold, with a surface covered in ice and cratered from billions of years of asteroid impacts. Its name comes from the Greek goddess who was the mother of Zeus.

One side always watches. Rhea is tidally locked, which means the same hemisphere always faces Saturn. It rotates and orbits at the same speed, so if you stood on Rhea, Saturn would never move in the sky.

A perfectly round shape. Rhea is the smallest body in the Solar System confirmed to be in hydrostatic equilibrium, meaning gravity has pulled it into a nearly perfect sphere. This makes it officially round enough to be considered a proper moon rather than just a floating rock.

A smooth, icy surface. Scientists believe Rhea may have a thin ring system around it, making it possibly the only moon with rings, though this discovery needs more study from future space missions.