Saturn Fact Sheet

Saturn/Earth Comparison

Bulk parameters

                                     Saturn      Earth   Ratio (Saturn/Earth)
Mass (1024 kg)                      568.46       5.9736       95.162
Volume (1010 km3)                    82,713    108.321       763.59
Radius (1 bar level) (km)
    Equatorial                       60,268      6,378         9.449
    Polar                            54,364      6,356         8.553
Volumetric mean radius (km)          58,232      6,371         9.140
Ellipticity                           0.0980     0.0034       28.82
Mean density (kg/m3)                    687      5,520         0.124
Gravity (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                           0.75       0.385         1.95
Visual geometric albedo               0.47       0.367         1.28
Visual magnitude V(1,0)              -8.88      -3.86            -
Solar irradiance (W/m2)              15.0        1,380.        0.011
Black-body temperature (K)           63.9      247.3           0.258
Moment of inertia (I/MR2)             0.210      0.3308        0.635
J2 (x 10-6)                      16,298.      1082.63         15.054    

Orbital parameters

                                     Saturn      Earth   Ratio (Saturn/Earth)
Semimajor axis (106 km)            1,426.8       149.6         9.537
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)                1,347.6       147.1         9.161
Aphelion (106 km)                  1,506.4       152.1         9.904
Synodic period (days)                378.09        -             -
Mean orbital velocity (km/s)           9.66       29.79        0.324
Orbit inclination (deg)                2.484       0.00          -
Orbit eccentricity                     0.05415     0.0167      3.243
Sidereal rotation period (hours)      10.500*     23.9345      0.439
Obliquity to orbit (deg)              26.73       23.45        1.140

* Saturnian System III coordinates

Saturn Observational Parameters

Discoverer:      Unknown
Discovery Date:  Prehistoric

Apparent diameter from Earth
        Maximum (seconds of arc)   20.1
        Minimum (seconds of arc)   14.5
Distance from Earth
        Minimum (106 km)         1195.5
        Maximum (106 km)         1658.5
Apparent magnitude at opposition    0.7      

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

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

Saturnian Atmosphere

Surface Pressure: >>100 bars
Average temperature: ~97 K
Temperature at 1 bar: ~134 K
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 (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

NASA Official: J. H. King, joseph.h.king@gsfc.nasa.gov
Last Updated: 27 November 1998, DRW