National Aeronautics and Space Administration

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Moons of

www..gov Saturn, the sixth from the , is home to a vast array • the planet in a direction opposite that of Saturn’s • Fastest of intriguing and unique — 53 plus 9 awaiting official larger , as do several of the recently discovered moons. Pan’s Orbit Around Saturn 13.8 confirmation. Christiaan discovered the first known • has an enormous crater on one side, the result of an • Number of Moons Discovered by Voyager 4 of Saturn. The year was 1655 and the moon is . impact that nearly split the moon apart. (, , , and Pan) Jean-Dominique made the next four discoveries: (1671), (1672), (1684), and (1684). Mimas and • displays evidence of active volcanism: Cassini • Number of Moons Discovered by Cassini 6 Enceladus were both discovered by in 1789. observed warm fractures where evaporating ice evidently es- (, , , , , and ) The next two discoveries came at intervals of 50 or more years capes and forms a huge of vapor over the (1848) and Phoebe (1898). pole. ABOUT THE IMAGES 1 Saturn’s fourth- As telescopic resolving power improved, Saturn’s family of • Hyperion has an odd flattened shape and rotates chaotically, 1 2 3 largest moon, Dione, is known moons grew. and were discovered probably due to a recent . in 1966. By the time Cassini–Huygens was launched in 1997, 4 5 seen through the haze high-resolution imaging techniques used on -based tele- • Pan orbits within the main rings and helps sweep materials out of the planet’s largest of a narrow space known as the Gap. moon, Titan, against scopes had added to the moon count. Cassini has discovered 6 7 8 Saturn and its rings. six moons and may find more during its mission. Cassini focuses • Tethys has a huge rift zone called Ithaca that runs its cameras mainly on objects relatively close to Saturn; the nearly three-quarters of the way around the moon. 2 (blue) emphasizes icy walls of fractures on bright rings complicate moon-hunting efforts. Earth-based tele- Enceladus. scopes on the outer part of the Saturn system, and have • Four moons orbit in stable places around Saturn called Lagran- 3 The Herschel crater on Mimas is a relic of a large impact found a number of moons in the outer regions. gian points. These places lie 60 degrees ahead of or behind a that nearly destroyed this moon. larger moon and in the same orbit. and occupy Each of Saturn’s moons bears a unique story. Two of the moons the two Lagrangian points of Tethys in its orbit; and Poly- 4 Titan’s makes Saturn’s largest moon look like a orbit within gaps in the main rings. Some, such as Prometheus deuces occupy the corresponding Lagrangian points of Dione. fuzzy orange in this natural-color view. and Pandora, interact with ring material, shepherding the ring in 5 A false-color view processed to enhance the individual jets its orbit. Some small moons are trapped in the same orbits as • Sixteen of Saturn’s moons keep the same face toward the spurting ice particles on Enceladus. Tethys or Dione. Janus and Epimetheus occasionally pass close planet as they orbit. Called “,” this is the same to each other, causing them to periodically exchange orbits. In phenomenon that keeps our Moon always facing toward Earth. 6 This image is a mosaic of images of Phoebe taken by 2006, Cassini found evidence for a new class of “” re- Cassini during its historic close encounter in June 2004. In addition to studies of Titan, Cassini continues to gather data siding within Saturn’s rings, sweeping out small gaps in the ring about many of the other satellites in an effort to fully understand 7 This image of Iapetus, the two-toned moon, shows the particles. There may be as many as 10 million moonlets within the , formation, and dynamics of Saturn’s many intriguing bright trailing hemisphere. just one of the rings. moons. 8 Cassini’s false-color image of Rhea enhances the slight Here’s a sampling of some of the unique aspects of the moons: differences in natural color across the moon’s face. FAST FACTS • Titan — At 5,150 kilometers (3,200 ) across, Titan is the FOR MORE INFORMATION • Largest Moon of Saturn Titan ’s second-largest moon. Titan hides its surface Titan’s 5,150 km (3,200 mi) solarsystem.nasa.gov/saturn beneath a thick, -rich atmosphere, but Cassini’s instru- For the most recent Saturn moon count, visit: ments have revealed that Titan possesses many parallels to • Closest Moon to Saturn Pan Earth — , , mountains, , and rivers. Titan’s solarsystem.nasa.gov/planets/profile.cfm?Object= Pan’s Distance from Saturn 133,583 km (83,022 mi) Saturn&Display=Moons atmosphere is approximately 95 percent nitrogen with traces of . While Earth’s atmosphere extends about 60 kilome- ters (37 miles) into space, Titan’s extends nearly 600 kilometers (10 times that of Earth’s atmosphere) into space.

• Iapetus has one side as bright as and one side as dark as velvet, with a huge ridge running around most of its dark-side .

Some of Saturn’s moons are shown at relative distances to the planet.

LG-2013-07-576-HQ — JPL 400-1489O 07/13