Planetary Ring Systems

Of all the planets, Saturn is the most instantly recognisable to everyone because of its beautiful system of rings, visible in even a small telescope, discovered by Galileo in 1610, but not recognised for what they are until Christiaan Huygens’ observations in 1655. Until 1977, Saturn’s rings were considered unique, but we now know that all four gas giants, Jupiter, Saturn, Uranus and Neptune are surrounded by ring systems. However, it is true that the rings of Saturn remain in a class of their own. James Clerk Maxwell’s fascination with the rings of Saturn was made clear in his 1857 Adams Prize essay. After quoting parts of Maxwell’s essay in their recent Scientific American article on rings ["Bejewelled Worlds", special edition entitled New Light on the Solar System, V. 13, No. 3, pp. 74-83, 2003], Burns, Hamilton and Showalter stated, "A century and a half later Saturn’s rings remain a symbol of all that is exotic and wondrous about the universe". Ellis Miner and Randii Wessen co-authored the successful Springer-Praxis book, Neptune: the planet, rings and satellites, published in December 2001 which has sold 1076 copies worldwide to date.

The scientific significance of planetary ring systems.- The discovery of the Saturn ring system.- The discovery of the Uranus ring system.- The discovery of the Jupiter ring system.- The discovery of the Neptune ring system.- Present knowledge of the Jupiter ring system.- Present knowledge of the Uranus ring system.- Present knowledge of the Neptune ring system.- Pre-Cassini knowledge of the Saturn ring system.- Early results about Saturn’s rings from Cassini.- Comparative planetology of the giant planet ring systems.- Anticipated future observations of planetary ring systems.