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	Saturn At a Glance
	Discovery Known since antiquity Name Roman god of agriculture Average Distance from Sun 885,904,700 miles 1,426,725,400 km 9.5 Astronomical Units Mass 95 times Earth's mass Equatorial Diameter 74,898 miles 120,536 km Length of Day 10 hours, 39 minutes Length of Year 29.4 Earth years Surface Gravity 0.74 that of Earth (If you weigh 100 pounds, you would weigh about 74 pounds on Saturn) Known Moons 62 (April 2009) Titan, Enceladus, Iapetus, and Mimas Compare Planets
	Exploration
	Cassini entered orbit around Saturn in the summer of 2004, and has transmitted tens of thousands of images of the planet and its rings and moons. On January 14, 2005, a second part of the mission, the Huygens probe, parachuted to a soft landing on Titan. Its images showed a landscape carved by flowing liquid. Cassini's instruments have peered through Titan's atmospheric haze to discover possible pools of liquid and a possible volcano on Titan's surface. Cassini is scheduled to continue its reconnaissance of the Saturn system until 2008. More»

The planet Saturn is a delicate giant. Although it is the second largest planet in the solar system, it's the least dense -- less dense than water. Chemical compounds in its upper atmosphere color its cloud bands in subtle shades of ivory, yellow, and tan. And broad, lacy rings encircle Saturn, making it the most beautiful planet in the solar system.

View in 2009

Like its larger sibling, Jupiter, Saturn is a ball of hydrogen and helium gas wrapped around a dense, rocky core. Saturn spins so fast that it bulges outward at the equator, so the planet is much thicker at the equator than through the poles.

Saturn’s clouds are colored in subtle shades of yellow and tan.

Saturn's clouds contain ammonia, methane, and other toxic compounds. They are buffeted by winds of up to 1,000 miles (1,600 km) per hour, and they contain violent storm systems that produce lightning blasts a million times more powerful than those on Earth.

Saturn's most prominent feature, though, is its extensive ring system.

Galileo Galilei discovered the rings in the early 17th century. In his small, crude telescope, though, they looked like "bumps" on the side of the planet. Five decades later, Dutch astronomer Christaan Huygens, who had recently discovered Saturn's largest moon, Titan, detected a bit of space between Saturn and the bumps. He deduced that the bumps were really planet-circling rings.

Today, astronomers know that thousands of individual rings make up Saturn's ring system. Some rings are made of small bits of frozen water, others contain tiny grains of dust, and still others are a mixture of the two. In all, the rings are only a few hundred feet thick. Several small moons orbit inside or just outside the ring system. These "shepherd" satellites help keep the ring particles in place, but they also sculpt some rings into odd shapes, with twists and kinks.

Saturn's rings probably formed when a small moon or a comet passed close to Saturn and was pulled apart by the planet's gravity.

French mathematician Edward Roche first described this process around 1850. A planet's gravity pulls more strongly on the side of a moon that is facing it than on the side that is away from it. If a moon passes too close to its parent planet, this difference, called tidal gravity, pulls it apart, turning the moon into cosmic rubble. Over time, the rubble spreads out to form rings -- like those that encircle Saturn.

Although Saturn has no solid surface to stand on, humans may someday view its rings from close range. They may walk on some of its icy moons or even float above Saturn's clouds in big balloons. From such a lofty vantage point, the rings would form wide, sparkling bands across the sky. Sometimes, icy particles from the inner edge of Saturn's rings may fall into the planet's atmosphere, creating bright "shooting stars" as they streak through the sky of this delicate giant.

View in 2009
Saturn looks like a bright golden star. It spends the first eight months of the year in Leo, the lion, then moves into the neighboring constellation Virgo, the virgin. Saturn is at its best in early March, when it's closest to Earth. It disappears behind the Sun in late August, then returns to view in the morning sky in October.

Saturn's Moons

1. Albiorix 2. Atlas 3. Calypso 4. Daphnis 5. Dione 6. Enceladus 7. Epimetheus 8. Erriapo 9. Helene 10. Hyperion 11. Iapetus 12. Ijiraq

13. Janus 14. Kiviuq 15. Mimas 16. Methone 17. Mundilfari 18. Paaliaq 19. Narvi 20. Pan 21. Pallene 22. Pandora 23. Phoebe 24. Polydeuces

25. Prometheus 26. Rhea 27. Siarnaq 28. Skadi 29. Suttung 30. Tarvos 31. Telesto 32. Tethys 33. Thrym 34. Titan 35. Ymir 36. S/2004 S7

37. S/2004 S8 38. S/2004 S9 39. S/2004 S10 40. S/2004 S11 41. S/2004 S12 42. S/2004 S13 43. S/2004 S14 44. S/2004 S15 45. S/2004 S16 46. S/2004 S17 47. S/2004 S18

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This document was last modified: May 04, 2009