Saturn

Saturn is probably best known for its famous planetary rings. They were first observed by Galileo Galilei in 1610 with his telescope, but he clearly did not know what to make of it. He wrote to the Grand Duke of Tuscany that "Saturn is not alone but is composed of three, which almost touch one another and never move nor change with respect to one another. They are arranged in a line parallel to the zodiac, and the middle one (Saturn itself) is about three times the size of the lateral ones (actually the edges of the rings)." He also described Saturn has having "ears." In 1612 the plane of the rings was oriented directly at the Earth and the rings appeared to vanish, and then in 1613 they reappeared again, further confusing Galileo. The riddle of the rings was not solved until 1655 by Christiaan Huygens, using a telescope much more powerful than the ones available to Galileo in his time. In 1675 Giovanni Cassini determined that Saturn's ring was actually composed of multiple smaller rings with gaps between them; the largest of these gaps was later named the Cassini Division.

         hey fuck all of you!

The rings can be seen in quite modest modern telescopes or a good pair of binoculars. They are composed of silica rock, iron oxide, and ice particles ranging in size from specks of dust to the size of a small automobile. There are two main theories regarding the origin of Saturn's rings. One theory, originally proposed by Edward Roche in the 19th century, is that the rings were once a moon of Saturn whose orbit decayed until it came close enough to be ripped apart by tidal forces. A variation of this theory is that the moon disintegrated after being struck by a large comet or asteroid. The second theory is that the rings were never part of a moon, but are instead left over from the original nebular material that Saturn formed out of. This theory is not widely accepted today, since Saturn's rings are thought to be unstable over periods of millions of years and therefore of relatively recent origin.

Saturn's moons

Saturn has a large number of moons, 18 of which have names. The exact number of moons is uncertain, there being large numbers of objects of all sizes in orbit around Saturn. A recent survey starting in late 2000 found another 12 moons in orbits suggesting that they were the fragments of larger bodies captured by Saturn (Nature vol. 412, p.163-166)

Saturn's natural satellites
Name	Diameter (km)	Mass (kg)	Mean orbital radius (km)	Orbital period
Pan	20	Unknown	133,583	0.575 days
Atlas	30 (40 x 20)	Unknown	137,670	0.6019 days
Prometheus	91 (145 x 85 x 62)	2.70×10¹⁷	139,350	0.6130 days
Pandora	84 (114 x 84 x 62)	2.20×10¹⁷	141,700	0.6285 days
Epimetheus	115 (144 x 108 x 98)	5.60×10¹⁷	151,422	0.6942 days	Co-orbital
Janus	178 (196 x 192 x 150)	2.01×10¹⁸	151,472	0.6945 days	Co-orbital
Mimas	392	3.80×10¹⁹	185,520	0.942422 days
Enceladus	498	7.30×10¹⁹	238,020	1.370218 days
Tethys	1060	6.22×10²⁰	294,660	1.887802 days	Co-orbital
Telesto	29 (34 x 28 x 36)	Unknown	294,660	1.887802 days
Calypso	26 (34 x 22 x 22)	Unknown	294,660	1.887802 days
Dione	1120	1.05×10²¹	377,400	2.736915 days	Co-orbital
Helene	33 (36 x 32 x 30)	Unknown	377,400	2.736915 days	Co-orbital
Rhea	1530	2.49×10²¹	527,040	4.5175 days
Titan	5150	1.35×10²³	1,221,830	15.94542 days
Hyperion	286 (410 x 260 x 220)	1.77×10¹⁹	1,481,100	21.27661 days
Iapetus	1460	1.88×10²¹	3,561,300	79.33018 days
Phoebe	220	4.00×10¹⁸	12,952,000	550.48 days

Solar system:
Sun - Mercury - Venus - Earth - Mars - Asteroids - Jupiter - Saturn - Uranus - Neptune - Pluto - Comets