| Orbital Elements | ||
| ||
| Mean distance from Sun | 778,330,000 km | = 5.203 astronomical units |
| Perihelion distance | 740,900,000 km | = 4.953 astronomical units |
| Aphelion distance | 815,700,000 km | = 5.453 astronomical units |
| Eccentricity of orbit | 0.0483 | |
| Inclination of orbit | 1.308° | relative to Earth's orbit |
| Period of orbit | 11.8623 years | |
| Synodic period | 399 days | relative to Earth |
| Mean orbital speed | 13.07 km/s | |
| Minimum orbital speed | 12.44 km/s | |
| Maximum orbital speed | 13.72 km/s | |
| Physical Properties | ||
| ||
| Mean diameter | 139,822 km | = 11 Earth diameters |
| Equatorial radius | 71,492 km | |
| Polar radius | 66,854 km | |
| Oblateness | 1/15 | |
| Mass | 1.900 x 1027 kg | = 317.94 Earth masses |
| Mean density | 1.33 g/cm3 | |
| Rotational period | 9.841 hours | at equator, where rotation is fastest |
| Inclination of axis | 3.13° | relative to the axis of its orbit |
| Gravity at cloud tops | 22.88 m/s2 | |
| Escape speed | 59.56 km/s | from cloud tops |
| Visual geometric albedo | 0.52 | |
| Visual magnitude (Vo) | -2.70 | maximum, as seen from Earth |
| Mean visible cloud temperature | -121°C | |
| Atmospheric pressure | 0.7 bar | at cloud tops |
| Atmosphere composition by mass | |
| |
| Hydrogen (H2) | 82% |
| Helium (He) | 17% |
| Methane (CH4) | |
| Ammonia (NH3) | |
| Water vapor (H2O) | |
Moons
Four large moons, easily visible through binoculars,
and more than 50 small moons.
To my Space and Science home page
for more about the Solar System
Jeff Root
September 4, 2003