Saturn has 34 named satellites:Of those moons for which rotation rates are known, all but Phoebe and Hyperion rotate synchronously.The three pairs Mimas-Tethys, Enceladus-Dione and Titan-Hyperion interact gravitationally in such a way as to maintain stable relationships between their orbits: the period of Mimas' orbit is exactly half that of Tethys, they are thus said to be in a 1:2 resonance; Enceladus-Dione are also 1:2; Titan-Hyperion are in a 3:4 resonance.

			Distance	Radius	Mass
Satellite	(000 km)	(km)	(kg)	Discoverer	Date
---------	---------	---------	---------	---------	---------
Atlas	138	14	?	Terrile	1980
Prometheus	139	46	2.70e17	Collins	1980
Pandora	142	46	2.20e17	Barnard	1980
Epimetheus	151	57	5.60e17	Walker	1980
Janus	151	89	2.01e18	Dollfus	1966
Mimas	186	196	3.80e19	Herschel	1789
Enceladus	238	260	8.40e19	Herschel	1789
Tethys	295	530	7.55e20	Cassini	1684
Telesto	295	15	?	Reitsema	1980
Calypso	295	13	?	Pascu	1980
Dione	377	560	1.05e21	Cassini	1684
Helene	377	16	?	Laques	1980
Rhea	527	765	2.49e21	Cassini	1672
Titan	1222	2575	1.35e23	Huygens	1655
Hyperion	1481	143	1.77e19	Bond	1848
Iapetus	3561	730	1.88e21	Cassini	1671
Phoebe	12952	110	4.00e18	Pickering	1898

Saturn's Rings

	Radius	Radius		approx.	approx.
Name	inner	outer	width	position	mass (kg)
----------	-----------	-----------	-------------	------------	-------------
D-Ring	67,000	74,500	74,500	(ring)
Guerin Division
C-Ring	74,500	92,000	17,500	(ring)	1.1e18
Maxwell Division	87,500	88,000	500	(divide)
B-Ring	92,000	117,500	25,500	(ring)	2.8e19
Cassini Division	115,800	120,600	4,800	(divide)
Huygens Gap	117,680	(n/a)	285-440	(subdiv)
A-Ring	122,200	136,800	14,600	(ring)	6.2e18
Encke Minima	126,430	129,940	3,500	29%-53%
Encke Division	133,410	133,740
Keeler Gap	136,510	136,550
F-Ring	140,210		30-500	(ring)
G-Ring	165,800	173,800	8,000	(ring)	1e7?
E-Ring	180,000	480,000	300,000	(ring)

Notes:
* distance is kilometers from Saturn's center
* the "Encke Minima" is a slang term used by amateur astronomers, not an official IAU designation
Uranus is the seventh planet from the Sun and the third largest (by diameter). Uranus is larger in diameter but smaller in mass than Neptune.
orbit:2,870,990,000 km (19.218 AU) from Sun
diameter:51,118 km (equatorial)
mass: 8.683e25 kg
Uranus is the ancient Greek deity of the Heavens, the earliest supreme god. Uranus was the son and mate of Gaia the father of Cronus (Saturn) and of the Cyclopes and Titans (predecessors of the Olympian gods).Uranus, the first planet discovered in modern times, was discovered by William Herschel while systematically searching the sky with his telescope on March 13, 1781. It had actually been seen many times before but ignored as simply another star (the earliest recorded sighting was in 1690 when John Flamsteed cataloged it as 34 Tauri). Herschel named it "the Georgium Sidus" (the Georgian Planet) in honor of his patron, the infamous (to Americans) King George III of England; others called it "Herschel". The name "Uranus" was first proposed by Bode in conformity with the other planetary names from classical mythology but didn't come into common use until 1850.

Uranus has been visited by only one spacecraft, Voyager 2 on Jan 24 1986.

Most of the planets spin on an axis nearly perpendicular to the plane of the ecliptic but Uranus' axis is almost parallel to the ecliptic. At the time of Voyager 2's passage, Uranus' South Pole was pointed almost directly at the Sun. This results in the odd fact that Uranus' Polar Regions receive more energy input from the Sun than do its equatorial regions. Uranus is nevertheless hotter at its equator than at its poles. The mechanism underlying this is unknown.

Actually, there's an ongoing battle over which of Uranus' poles is its north pole! Either its axial inclination is a bit over 90 degrees and its rotation is direct, or it's a bit less than 90 degrees and the rotation is retrograde. The problem is that you need to draw a dividing line *somewhere*, because in a case like Venus there is little dispute that the rotation is indeed retrograde (not a direct rotation with an inclination of nearly 180).

Like Jupiter, Saturn is about 75% hydrogen and 25% helium with traces of water, methane, ammonia and "rock", similar to the composition of the primordial Solar Nebula from which the solar system was formed.

Uranus is composed primarily of rock and various ices, with only about 15% hydrogen and a little helium (in contrast to Jupiter and Saturn which are mostly hydrogen). Uranus (and Neptune) are in many ways similar to the cores of Jupiter and Saturn minus the massive liquid metallic hydrogen envelope. It appears that Uranus does not have a rocky core like Jupiter and Saturn but rather that its material is more or less uniformly distributed.

Uranus' atmosphere is about 83% hydrogen, 15% helium and 2% methane.Uranus' blue color is the result of absorption of red light by methane in the upper atmosphere. There may be colored bands like Jupiter's but they are hidden from view by the overlaying methane layer. Like the other gas planets, Uranus has rings. Like Jupiter's, they are very dark but like Saturn's they are composed of fairly large particles ranging up to 10 meters in diameter in addition to fine dust. There are 11 known rings, all very faint; the brightest is known as the Epsilon ring. The Uranian rings were the first after Saturn's to be discovered. This was of considerable importance since we now know that rings are a common feature of planets, not a peculiarity of Saturn alone.

Voyager 2 discovered 10 small moons in addition to the 5 large ones already known. It is likely that there are several more tiny satellites within the rings.Uranus' magnetic field is odd in that it is not centered on the center of the planet and is tilted almost 60 degrees with respect to the axis of rotation. It is probably generated by motion at relatively shallow depths within Uranus.