Prometheus

Saturn · moon · shepherd moon · space discovery

Tiny ring shepherd. Prometheus is one of Saturn's smallest moons, only about 86 kilometers long, and it acts like a cosmic shepherd by keeping Saturn's ring particles in place with its gravity. Its gravitational tug helps prevent the rings from spreading out into space.

Discovered by Voyager. Astronomers found Prometheus in October 1980 using pictures taken by the Voyager 1 space probe as it traveled past Saturn. At first they just called it S/1980 S 27 until they officially named it a few years later.

Named after Prometheus. The moon was named in 1985 after Prometheus, a Titan from ancient Greek stories who was famous for stealing fire from the gods and giving it to humans. Prometheus has designation Saturn XVI, meaning it's the 16th moon of Saturn that astronomers have officially named.

Weird oval shape. Unlike round moons, Prometheus has an unusual elongated shape, more like a stretched-out potato than a sphere. This odd shape makes it even more interesting to scientists studying how moons form and change over time.

Inner moon orbit. Prometheus orbits very close to Saturn, much closer than Earth's moon orbits Earth, completing one full orbit around Saturn every 14.7 hours. It sits right near Saturn's famous A-ring, where it does its shepherd job.