Planetary Ring Systems Brenton C. Davis Tuesday, April 20 th 2010

The History of the Rings Long ago, Sauron created the One… In 1610 Galileo Galilei first observed, but was unable to identify Saturn’s Rings To further mystify Galileo, the rings “disappeared” in 1612 and “reappeared” in 1613

A New Ringbearer It wasn’t until 1655 that Christiaan Huygens suggested that Saturn was surrounded by a ring. Robert Hooke added to this observation by the notation of shadow’s on the rings.

Coming to the Present In 1675, Giovanni Cassini discovers gaps in a system of concentric rings Pierre-Simon Laplace suggested, in 1787, that these ringlets were solid However, through the careful application of Newton’s Law of Universal Gravitation, James Maxwell was able to prove they must be composed of numerous small particles

The Present Model Name (3) Distance from Saturn Width (km) (4) (from center, in km) (4) D Ring 66,900 – 74,5107,500 C Ring 74,658 – 92,00017,500 B Ring 92,000 – 117,58025,500 Cassini Division 117,580 – 122,1704,700 A Ring 122,170 – 136,77514,600 Roche Division 136,775 – 139,3802,600 F Ring 140,180 (1) 30 – 500 Janus/Epimetheus Ring 149,000 – 154,0005,000 G Ring 166,000 – 175,0009,000 Methone Ring Arc 194,230? Anthe Ring Arc 197,665? Pallene Ring 211,000 – 213,5002,500 E Ring 180,000 – 480,000300,000 Phoebe Ring ~4,000,000 – >13,000,000

There are more rings? In the 1970’s and the 1980’s rings were discovered around the other three gas giants The Neptune and Uranus’ rings were detected indirectly. Jupiter was observed by the Voyager 1 Space Probe

Planetary Ring Formation Collisions Keplerian Shear Shepherd Moons Orbital Resonances