b

Properties

    Saturn is the sixth planet from the Sun and is the second largest in the solar system with an equatorial diameter of 119,300 kilometers (74,130 miles).

    Saturn is visibly flattened at the poles, a result of the very fast rotation of the planet on its axis.
 
    Its day is 10 hours, 39 minutes long, and it takes 29.5 Earth years to revolve about the Sun.

Atmosphere

    The atmosphere is primarily composed of hydrogen with small amounts of helium and methane.

    Saturn is the only planet less dense than water (about 30 percent less).

    The wind blows at high speeds on Saturn. Near the equator, it reaches velocities of 500 meters a second (1,100 miles an hour).
 

Moons

    Saturn has 18 confirmed moons, the largest number of satellites of any planet in the solar system.
 

Voyager 2's Route

Mass (kg) ------------------------------------------------------------------- 5.688 x 10²⁶
Mass (Earth = 1) ------------------------------------------------------------ 95.181
Equatorial radius (km) ------------------------------------------------------- 60,268
Equatorial radius (Earth = 1) ------------------------------------------------- 9.4494
Mean density (gm/cm³) ------------------------------------------------------ 0.69
Mean distance from the Sun (km) -------------------------------------------  1,429,400,000
Mean distance from the Sun (Earth = 1) -------------------------------------- 9.5388
Rotational period (hours) -----------------------------------------------------10.233
Orbital period (years) -------------------------------------------------------- 29.458
Mean orbital velocity (km/sec) ----------------------------------------------- 9.67
Orbital eccentricity ----------------------------------------------------------- 0.0560
Tilt of axis (degrees) ---------------------------------------------------------- 25.33
Orbital inclination (degrees) --------------------------------------------------- 2.488
Equatorial surface gravity (m/sec²) -------------------------------------------- 9.05
Equatorial escape velocity (km/sec) ------------------------------------------- 35.49
Visual geometric albedo ------------------------------------------------------- 0.47
Magnitude (Vo) --------------------------------------------------------------- 0.67
Mean cloud temperature ------------------------------------------------------ -125°C
Atmospheric pressure (bars) --------------------------------------------------- 1.4
Atmospheric composition --------------------------------------------- Hydrogen 97%, Helium 3%
 

Mosaic of Saturn and its moons
 

Saturn’s Moons:

    Saturn has 18 officially recognized and named satellites. In addition, there are other unconfirmed satellites. One circles in the orbit of Dione, a second is located between the orbits of Tethys and Dione, and a third is located between Dione and Rhea.

    Only Titan has an appreciable atmosphere.

    Most of the satellites have a synchronous rotation. The exceptions are Hyperion, which has a chaotic orbit, and Phoebe.

    Saturn has a regular system of satellites. That is, the satellites have nearly circular orbits and lie in the equatorial plane. The two exceptions are Iapetus and Phoebe.

    All of the satellites have a density of < 2 gm/cm³. This indicates they are composed of 30 to 40% rock and 60 to 70% water ice.

    Most of the satellites reflect 60 to 90% of the light that strikes them. The outer four satellites reflect less than this and Phoebe reflects only 2% of the light that strikes it.
 
 

Saturn's Moons (A Summary)

Moon	#	Radius (km)	Mass (kg)	Distance (km)	Discoverer	Date
Pan	XVIII	9.655	?	133,583	M.Showalter	1990
Atlas	XV	20x15	?	137,640	R. Terrile	1980
Prometheus	XVI	72.5x42.5x32.5	2.7e+17	139,350	S. Collins	1980
Pandora	XVII	57x42x31	2.2e+17	141,700	S. Collins	1980
Epimetheus	XI	72x54x49	5.6e+17	151,422	R. Walker	1966
Janus	X	98x96x75	2.01e+18	151,472	A. Dollfus	1966
Mimas	I	196	3.80e+19	185,520	W.Herschel	1789
Enceladus	II	250	8.40e+19	238,020	W. Herschel	1789
Tethys	III	530	7.55e+20	294,660	G. Cassini	1684
Telesto	XIII	17x14x13	?	294,660	B. Smith	1980
Calypso	XIV	17x11x11	?	294,660	B. Smith	1980
Dione	IV	560	1.05e+21	377,400	G. Cassini	1684
Helene	XII	18x16x15	?	377,400	Laques -Lecacheux	1980
Rhea	V	765	2.49e+21	527,040	G. Cassini	1672
Titan	VI	2,575	1.35e+23	1,221,850	C. Huygens	1655
Hyperion	VII	205x130x110	1.77e+19	1,481,000	W. Bond	1848
Iapetus	VIII	730	1.88e+21	3,561,300	G. Cassini	1671
Phoebe	IX	110	4.0e+18	12,952,000	W. Pickering	1898

 

The Complex ring systems.

Rings

    Saturn's ring system is split into a number of different parts, which include the bright A and B rings and a fainter C ring.
 
    The ring system has various gaps. The most notable gap is the Cassini  Division, which separates the A and B rings. Giovanni Cassini discovered this division in 1675.

    The Encke Division, which splits the A Ring, is named after Johann Encke, who discovered it in 1837.

    Space probes have shown that the main rings are really made up of a large number of narrow ringlets.

    The rings show a significant amount of water. They may be composed of icebergs and/or snowballs from a few centimeters to a few meters in size.

    Much of the elaborate structure of some of the rings is due to the gravitational effects of nearby satellites.

    This phenomenon is demonstrated by the relationship between the F-ring and two small moons that shepherd the ring material.
 
    Radial, spoke-like features in the broad B-ring were also found by the Voyagers. The features are believed to be composed of fine, dust-size particles.
 

    The Cassini Space probe is to extend Voyager's discoveries and uncover more truths about Saturn.
 

• Summarised  information (Word 97 document)
• Information extracted from Britannica 97