Saturn

Saturn is the second largest planet in the solar system and the sixth planet counting outward from the Sun and the third outermost. It is known for having a ring system: flat, visible rings of material around it, within the plane of its equator. (Similar but lesser ring systems have been detected around other solar system planets now that space probes have viewed them from nearby. ) To some extent, Saturn's ring system has served as a physical example of an astrophysical disk, being close enough for detailed study. Among Saturn's 140+ known moons are Titan, Mimas, Enceladus, Tethys, Dione, Rhea, Iapetus, and Hyperion. Characteristics of Saturn:

• 95 Earth masses.
• 9 Earth radii.
• 10.5 hours - solar day.
• 29.5 years - orbital period.
• 9.5 AU - orbital radius (semi-major axis).
• 0.0565 - orbital eccentricity.

Space missions to Saturn have included Pioneer, Voyager, and Cassini. Its distance from Earth limits the number of such missions. The Cassini mission was long and extensive and vastly increased our knowledge about Saturn and its moons, and revealed Enceladus to be a prime candidate for extraterrestrial life. Concepts developed for possible future Saturn-system missions include Dragonfly and Enceladus Life Finder.