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Saturn is the second
largest planet in the solar system. Its existence has been known since prehistoric times.
It has an equatorial diameter of 120 536 km and a polar diameter of 108 728 km. The large
difference between the equatorial diameter and the polar diameter is caused by the high
speed at which the planet spins around its axis. While the other gas planets are also
oblate, (flattened at the poles), they are all less oblate than Saturn.
Saturn has a mass of 5.69x1029kg; however, Saturn has a low density of only
0.69 g/cm3. Due to the low density, the planet has a volume 764 times larger
than Earth, but is only 96 times more massive. Since the density of Saturn is lower than
that of water, (at 1 g/cm3), Saturn would float on water if a body of water
large enough existed.
Above the clouds, the atmosphere is 97% hydrogen and 36% helium and 0.05% methane. The
planet as a whole is 75% hydrogen, 25% helium, with traces of water, methane, ammonia, and
solids. The core of Saturn is made of rock, surrounded by a liquid metal layer and then a
layer of molecular hydrogen (H2). There are also traces of ice. The core
temperature is 12,000K, while the exterior is extremely cold, 88K, or –185oC.
Saturn release about twice as much heat to space as it receives from the sun.
Near the surface, winds reach a velocity of 500 meters per second, (1800km/h)! In 1990,
the HST discovered a large white spot that was not present when the Voyager spacecraft
were there. This white spot is believed to be a large storm.
Saturn rotates completely on its axis every 10.2 hours and has a revolution period of
29.46 years at an average distance from the sun of 9.539AU.
Saturn has the same bands of colour found on Jupiter, however they are much fainter than
those found on Jupiter.
Saturn has a strong magnetic atmosphere, and unlike Jupiter and Earth, this field is
aligned with Saturn’s axis of rotation.
TABLES
Earth
Comparisons
Statistics |
Saturn |
Earth |
Saturn/Earth Ratio |
Mass |
568.46 x 1024kg |
5.9736 x 1024kg |
95.162 |
Volume |
82,713 x 1010km3 |
108.321 x 1010km3 |
763.59 |
Equatorial Radius |
60,296 km |
6,378 km |
9.449 |
Polar Radius |
54,364 km |
6,356 km |
8.553 |
Volumetric Mean Radius |
58,232 km |
6,371 km |
9.140 |
Ellipticity |
0.0980 |
0.0034 |
28.28 |
Mean Density |
687 kg/m3 |
5,520 kg/m3 |
0.124 |
Gravity (eg., 1 bar) |
35.5 m/s2 |
9.78 m/s2 |
3.62 |
Escape Velocity |
35.5 km/s |
11.19 km/s |
3.172 |
Moment of Inertia |
0.210 I/MR2 |
0.3308 I/MR2 |
0.635 |
Average Temperature |
97 K (-176oC) |
288 K (15oC) |
0.34 |
Bulk Parameters
Mass |
5.6876 x 1026kg |
Volume |
8.2713 x 1014km3 |
Radius (1 bar level)
Equatorial
Polar |
6.0268 x 107m
5.4364 000 x 107m
|
Volumetric Mean Radius |
5.8232 x 107m |
Ellipticity |
0.0980 |
Average Density |
687 kg/m3 |
Acceleration due to Gravity (e.g. 1 bar) |
8.96m/s2 |
Escape Velocity |
3.55 x 104 m/s |
GM |
37.931 x 106km3/s2 |
Band Albedo |
0.75 |
Visual Albedo |
0.47 |
Visual Magnitude V(1,0) |
-8.88 |
Solar Irradiance |
15.0 W/m2 |
Black-Body Temp |
63.9 K |
Moment of Inertia |
0.210 I/MR2 |
J2 |
16 298 x 10-6 |
Oblateness |
0.09796 |
Orbital Parameters
Semi-Major Axis |
1.4268 x 1012m
9.5349492 AU |
Sidereal Orbit Period |
10759.22 days
29.423519 years |
Tropical Orbit Period |
10746.94 d |
Pelihelion |
1347.6 x 109m |
Aphelion |
1506.4 x 109m |
Synodic Period |
378.09 d |
Mean Orbital Velocity |
9.66 x 103m/s |
Orbit Inclination |
2.48446 degrees |
Orbit Eccentricity |
0.05415060 |
Siderial Rotation Period |
10.500 h |
Obliquity to Orbit |
26.73 degrees |
Mean Motion |
0.0334979 degrees/day |
Solar Distance - mean |
1430 x 109m
9.56 AU |
Solar Distance - min |
1350 x 109m
9.02 AU |
Solar Distance - max |
1510 x 109m
10.09 AU |
Saturn Observational Parameters
Distance from Earth
min
max |
1195.5 x 1012m
1658.5 x 109m
|
Apparent diameter from Earth
Maximum
Minimum |
20.1 seconds of arc
14.5 seconds of arc
|
Apparent magnitude at opposition |
0.7 |
Saturn Mean Orbital Elements (J2000)
Semi Major Axis |
9.53707032 AU |
Longitude of Ascending Node |
113.71504 degrees |
Longitude of Pelihedron |
92.43194 degrees |
Mean Longitude |
49.94432 degrees |
Saturnian Magnetosphere
Dipole Field Strength |
0.218 gauss - Rs3
4.70 x 10 28cm3 |
Dipole Tilt to Rotational Axis |
< 1 degree |
Dipole Offset (planet centre to dipole centre) Distance |
0.04 to 0.05 Rs* northward |
*Rs is the radius of Saturn: 60330 km
Saturnian Atmosphere
Surface Pressure |
<< 100 bars |
Average Temperature |
~ 97 K |
Temperature at 1 Bar |
~ 134 K |
Density at 1 Bar |
~ 0.19kg/m3 |
Windspeed |
Up to ~ 400 m/s (< 30 degrees latitude)
Up to ~ 150 m/s (> 30 degrees latitude) |
Scale height |
5.95 X 104m |
Mean molecular Weight |
2.07 g/mol |
Atomosphere Composition (uncertainty in
parentheses)
Major |
H2 - 96.3% (2.4 %)
He 3.25% (2.4 %) |
Minor (in PPM) |
Methane CH4 4500 (2000)
Ammonia NH3 125 (75)
Hydrogen Detoured (HD) 110 (58)
Ethane C2H6 7 (1.5) |
Aerosols |
Amonia Ice,
Water Ice,
Ammonia Hydrosulphide |
|
