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Saturn/Earth Comparison

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Bulk parameters

                                     Saturn      Earth   Ratio (Saturn/Earth)
Mass (1024 kg)                      568.36       5.9726       95.159 
Volume (1010 km3)                    82,713    108.321       763.59
Radius (1 bar level) (km)
    Equatorial                       60,268      6,378.1       9.449   
    Polar                            54,364      6,356.8       8.552
Volumetric mean radius (km)          58,232      6,371.0       9.140
Ellipticity (Flattening)              0.09796    0.00335      29.24
Mean density (kg/m3)                    687      5,514         0.125
Gravity (eq., 1 bar) (m/s2)          10.44       9.80          1.065 
Acceleration (eq., 1 bar) (m/s2)      8.96       9.78          0.916 
Escape velocity (km/s)               35.5       11.19          3.172
GM (x 106 km3/s2)                    37.931      0.3986       95.16
Bond albedo                           0.342      0.306         1.12
Visual geometric albedo               0.47       0.367         1.28
Visual magnitude V(1,0)              -8.88      -3.86            -
Solar irradiance (W/m2)              14.90       1,367.6       0.011
Black-body temperature (K)           81.1      254.3           0.319
Moment of inertia (I/MR2)             0.210      0.3308        0.635
J2 (x 10-6)                      16,298.      1082.63         15.054    
Number of natural satellites         62          1
Planetary ring system               Yes         No

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Orbital parameters

                                     Saturn      Earth   Ratio (Saturn/Earth)
Semimajor axis (106 km)            1,433.53      149.60        9.582
Sidereal orbit period (days)      10,759.22      365.256      29.457   
Tropical orbit period (days)      10,746.94      365.242      29.424
Perihelion (106 km)                1,352.55      147.09        9.195      
Aphelion (106 km)                  1,514.50      152.10        9.957
Synodic period (days)                378.09        -             -
Mean orbital velocity (km/s)           9.68       29.78        0.325    
Max. orbital velocity (km/s)          10.18       30.29        0.336        
Min. orbital velocity (km/s)           9.09       29.29        0.310       
Orbit inclination (deg)                2.485       0.000         -
Orbit eccentricity                     0.0565      0.0167      3.383
Sidereal rotation period (hours)      10.656*     23.9345      0.445
Length of day (hrs)                   10.656      24.0000      0.444
Obliquity to orbit (deg)              26.73       23.44        1.140

* Saturnian System III coordinates

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Saturn Observational Parameters

Discoverer:      Unknown
Discovery Date:  Prehistoric

Distance from Earth
        Minimum (106 km)         1195.5
        Maximum (106 km)         1658.5
Apparent diameter from Earth
        Maximum (seconds of arc)   20.1
        Minimum (seconds of arc)   14.5
Mean values at opposition from Earth
        Distance from Earth (106 km)       1277.42    
        Apparent diameter (seconds of arc)   19.5
        Apparent visual magnitude             0.7 
Maximum apparent visual magnitude             0.43     

Saturn Mean Orbital Elements (J2000)

Semimajor axis (AU)                  9.53707032  
Orbital eccentricity                 0.05415060   
Orbital inclination (deg)            2.48446   
Longitude of ascending node (deg)  113.71504   
Longitude of perihelion (deg)       92.43194   
Mean Longitude (deg)                49.94432

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North Pole of Rotation

Right Ascension: 40.5954 - 0.0577T
Declination    : 83.5380 - 0.0066T
Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)
T = Julian centuries from reference date 

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Saturnian Magnetosphere

Dipole field strength: 0.210 gauss-Rs3
Dipole tilt to rotational axis: < 1 degree
Dipole offset (planet center to dipole center) distance: 0.04 to 0.05 Rs northward

Note: Saturn’s magnetic field has significant quadrapole and octapole moments,
making approximation of the central field as an offset dipole difficult.
Rs denotes Saturnian radii, 60,330 km

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Saturnian Atmosphere

Surface Pressure: >>1000 bars  
Temperature at 1 bar: 134 K (-139 C)
Temperature at 0.1 bar: 84 K (-189 C)
Density at 1 bar: 0.19 kg/m3
Wind speeds
   Up to 400 m/s (<30 degrees latitude)
   Up to 150 m/s (>30 degrees latitude)
Scale height: 59.5 km
Mean molecular weight: 2.07 g/mole
Atmospheric composition (by volume, uncertainty in parentheses)
    Major:       Molecular hydrogen (H2) - 96.3% (2.4%); Helium (He) - 3.25% (2.4%)
    Minor (ppm): Methane (CH4) - 4500 (2000); Ammonia (NH3) - 125 (75);
                 Hydrogen Deuteride (HD) - 110 (58); Ethane (C2H6) - 7 (1.5)
    Aerosols:    Ammonia ice, water ice, ammonia hydrosulfide

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