Voyager 2 image July 21, 1981, a month before its closest approach.  The moons are Rhea and Dione.

The material which forms the rings is less than 0.1% the amount of material in either moon.

Orbital Elements
Mean distance from Sun1,429,400,000 km    =    9.5388 astronomical units
Perihelion distance1,352,550,000 km=    9.0412 astronomical units
Aphelion distance1,514,500,000 km=    10.1238 astronomical units
Eccentricity of orbit0.0560
Inclination of orbit2.488relative to Earth's orbit
Period of orbit29.458 years
Synodic period378 daysrelative to Earth
Mean orbital speed9.67 km/s
Minimum orbital speed9.09 km/s
Maximum orbital speed10.18 km/s
Physical Properties
Mean diameter116,464 km=    9.2  Earth diameters
Equatorial radius60,268 km
Polar radius54,364 km
Mass5.688 x 1026 kg=    95.181 Earth masses
Mean density0.69 g/cm3
Rotational period10.233 hours
Inclination of axis25.33relative to the axis of its orbit
Gravity at cloud tops9.05 m/s2
Escape speed35.5 km/sfrom cloud tops
Visual geometric albedo0.47
Visual magnitude (Vo)0.67maximum, as seen from Earth
Mean visible cloud temperature    -125C
Atmospheric pressure1.4 barsat cloud tops

Atmospheric Composition
Hydrogen (H2)96.3%
Helium (He)3.25%


One large moon, four medium-size moons, and more than two dozen small moons.

HomeTo my Space and Science home page  for more about the Solar System

Jeff Root
September 4, 2003