Discoverer: Unknown
Spacecraft Encounter(s): Pioneer 10 & 11 (1973, 1974)
Voyager 1 & 2 (1979)
Galileo (1995 - 2003)
Cassini - Huygens (2000-2001)
New Horizons (2007)
Mean distance from the Sun: 5.203 AU
(778,400,000 km/483,700,000 mi)
Length of Year: 11.86 years
Rotation Period: 9.92 hours
Mean Orbital Velocity: 13.06 km/s (8.1 mi/s)
Inclination of Axis: 3.12°
Diameter: 142,980 km/88,846 mi
Number of observed satellites: more than 60
