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Bulk Parameters,
Orbital Parameters, Observational Parameters, Mean
Orbital Elements, Magnetosphere, Atmosphere.
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| Uranus
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| Bulk Parameters | Uranus | Earth | Ratio (Uranus/Earth) |
| Mass (1024 kg) | 86.832 | 5.9736 | 14.536 |
| Volume (1010 km3) | 6833 | 108.321 | 63.08 |
| Equatorial Radius (km) | 25559 | 6378.1 | 4.007 |
| Polar radius (km) | 24973 | 6356 | 3.929 |
| Volumetric mean radius (km) | 25362 | 6371 | 3.981 |
| Ellipticity | 0.02293 | 0.0034 | 6.84 |
| Mean density (kg/m3) | 1270 | 5515 | 0.230 |
| Surface gravity (eq.) (m/s2) | 8.69 | 9.78 | 0.889 |
| Escape velocity (km/s) | 21.3 | 11.2 | 1.903 |
| GM (x 106 km3/s2) | 5.794 | 0.3986 | 14.536 |
| Bond albedo | 0.300 | 0.385 | 0.98 |
| Visual geometric albedo | 0.51 | 0.367 | 1.390 |
| Visual magnitude V (1,0) | -7.19 | -3.86 | - |
| Solar irradiance (W/m2) | 3.71 | 1367.6 | 0.0027 |
| Black-body temperature (K) | 58.2 | 254.3 | 0.229 |
| Moment of inertia (I/MR2) | 0.225 | 0.3308 | 0.680 |
| J2 (x 10-6) | 3343.43 | 1082.63 | 3.088 |
| Orbital Parameters | Uranus | Earth | Ratio (Uranus/Earth) |
| Semimajor axis (106 km) | 2872.46 | 149.6 | 19.201 |
| Sidereal orbit period (days) | 30685.4 | 365.256 | 84.011 |
| Tropical orbit period (days) | 30588.740 | 356.242 | 83.749 |
| Perihelion (106 km) | 2741.3 | 147.1 | 18.637 |
| Aphelion (106 km) | 3003.62 | 152.1 | 19.748 |
| Synodic period (days) | 369.66 | - | - |
| Mean orbital velocity (km/s) | 6.81 | 29.79 | 0.229 |
| Max. orbital velocity (km/s) | 7.11 | 30.29 | 0.235 |
| Min. orbital velocity (km/s) | 6.49 | 29.29 | 0.222 |
| Orbital inclination (deg) | 0.772 | 0.00 | - |
| Orbit eccentricity | 0.0457 | 0.0167 | 2.737 |
| Sidereal rotation period (hrs) | -17.24* | 23.9345 | 0.720 |
| Length of day (hrs) | 17.24 | 24.0000 | 0.718 |
| Obliquity to orbit (deg) | 97.77 | 23.45 | 4.169 |
| * magnetic coordinates (as determined by the Voyager 2 Radio Science experiment | |||
| Observational Parameters | |||
| Discoverer: | William Herschel | ||
| Discovery Date: | 13 March 1781 | ||
| Apparent diameter from Earth | Maximum | 4.1 | |
| (seconds of arc): | Minimum | 3.3 | |
| Distance from Earth | Maximum | 3157.3 | |
| (106 km): | Minimum | 2581.9 | |
| Mean values at opposition from Earth: | Distance from Earth: 2719.99 x 10^6 km | Apparent diameter (seconds of arc): 3.9 | Apparent Visual magnitude: 5.5 |
| Mean Orbital Elements (J200) | |||
| Semimajor axis (A.U.) | 19.19126393 | ||
| Orbital eccentricity | 0.04716771 | ||
| Orbital inclination (deg) | 0.76986 | ||
| Longitude of ascending node | 74.22988 | ||
| Longitude of perihelion (deg) | 170.96424 | ||
| Mean Longitude (deg) | 313.23218 | ||
| Magnetosphere | |||
| Dipole field strength | 0.228 gauss-Ru3 | Ru = a Uranus radii = 25,600 km | |
| Dipole tilt to rotational axis | 58.6 degrees | ||
| Dipole offset (planet center to dipole center) distance: | 0.3 Ru along the rotation axis | ||
| Atmosphere | |||
| Surface Pressure | >>100 bars | ||
| Surface Density (at 1 bar) | ~ 0.42 kg/m3 | ||
| Scale Height | 27.7 km | ||
| Average temperature | ~58 K | ||
| Temperature at 1 bar: | ~76 K | ||
| Wind speeds | 0-200 m/s | ||
| Mean molecular weight | 2.64 g/ mole | ||
| Atmospheric Composition: | Major: | ||
| (uncertainty in parentheses) | Molecular Hydrogen (H2) - 82.5% (3.3%) | Methane (CH4)- ~2.3% | |
| Helium (He) - 15.2% (3.3%) | |||
| Minor (ppm): | Hydrogen Deuteride (HD) - ~148 | ||
| Aerosols: | Ammonia ice, water ice, ammonia hydrosulfide, methane ice (?) | ||
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Fact sheet source from NSSDC/NASA |