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Uranus Fact Sheet


Uranus Fact Sheet



Uranus/Earth Comparison


Bulk parameters


   Uranus
   EarthRatio
(Uranus/Earth) Mass (1024 kg)86.813 5.9724 14.54 Volume (1010 km3)6,833 108.321 63.08 Equatorial radius (1 bar level) (km)25,559 6,378.1 4.007 Polar radius (1 bar level) (km)24,973 6,356.8 3.929 Volumetric mean radius (km)25,362 6,371.0 3.981 Ellipticity (Flattening)0.02293 0.00335 6.84 Mean density (kg/m3)1,271 5,514 0.231 Gravity (eq., 1 bar) (m/s2)8.87 9.80 0.905 Acceleration (eq., 1 bar) (m/s2)8.69 9.78 0.889 Escape velocity (km/s)21.3 11.19 1.903 GM (x 106 km3/s2)5.7940 0.39860 14.54 Bond albedo0.300 0.306 0.980 Geometric albedo0.488 0.434 1.12 V-band magnitude V(1,0)-7.11 -3.99 - Solar irradiance (W/m2)3.69 1,361.0 0.0027 Black-body temperature (K)58.1 254.0 0.229 Moment of inertia (I/MR2)0.225 0.3308 0.680 J2 (x 10-6)3343.43 1082.63 3.088 Number of natural satellites27 1 Planetary ring systemYes No

Orbital parameters


   Uranus
   EarthRatio
(Uranus/Earth) Semimajor axis (106 km)2,872.46 149.60 19.201 Sidereal orbit period (days)30,685.4 365.256 84.011 Tropical orbit period (days)30,588.740 365.242 83.749 Perihelion (106 km)2,741.30 147.09 18.637 Aphelion (106 km)3,003.62 152.10 19.748 Synodic period (days)369.66 - - Mean orbital velocity (km/s)6.80 29.78 0.228 Max. orbital velocity (km/s)7.11 30.29 0.235 Min. orbital velocity (km/s)6.49 29.29 0.222 Orbit inclination (deg)0.772 0.000 - Orbit eccentricity0.0457 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 23.44 - Inclination of equator (deg)82.23 23.44 3.508

* Magnetic coordinates (as determined by the Voyager 2 Radio Science experiment)

Uranus Observational Parameters

Discoverer:      William Herschel
Discovery Date:  13 March 1781

Distance from Earth
        Minimum (106 km)         2581.9
        Maximum (106 km)         3157.3
Apparent diameter from Earth
        Maximum (seconds of arc)    4.1
        Minimum (seconds of arc)    3.3
Mean values at opposition from Earth
        Distance from Earth (106 km)       2719.99    
        Apparent diameter (seconds of arc)    3.9
        Apparent visual magnitude             5.57  
Maximum apparent visual magnitude             5.38   

Uranus Mean Orbital Elements (J2000)

Semimajor axis (AU)                 19.19126393  
Orbital eccentricity                 0.04716771   
Orbital inclination (deg)            0.76986   
Longitude of ascending node (deg)   74.22988  
Longitude of perihelion (deg)      170.96424  
Mean Longitude (deg)               313.23218

North Pole of Rotation

Right Ascension: 257.311
Declination    : -15.175
Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)

Uranian Magnetosphere

Model GSFC-O3
Dipole field strength: 0.228 Gauss-Ru3
Dipole tilt to rotational axis: 58.6 degrees
Longitude of tilt: 53.6 degrees
Dipole offset: 0.352 Ru
Surface (1 Ru) field strength: ~0.1 - 1.0 Gauss

Ru denotes Uranian model radius, here defined to be 25,600 km

Uranian Atmosphere

Surface Pressure: >>1000 bars  
Temperature at 1 bar: 76 K (-197 C)
Temperature at 0.1 bar: 53 K (-220 C)
Density at 1 bar: 0.42 kg/m3
Wind speeds: 0-250 m/s
Scale height: 27.7 km
Mean molecular weight: 2.64 
Atmospheric composition (by volume, uncertainty in parentheses)
    Major:       Molecular hydrogen (H2) - 82.5% (3.3%); Helium (He) - 15.2% (3.3%)
                 Methane (CH4) - 2.3%
    Minor (ppm): Hydrogen Deuteride (HD) - 148
    Aerosols:    Ammonia ice, water ice, ammonia hydrosulfide, methane ice(?)

Uranian Satellite Fact Sheet
Uranian Rings Fact Sheet

Planetary Fact Table - metric units
Planetary Fact Table - U.S. units
Planetary Fact Table - Earth ratio

Uranus Home Page
Directory to other Planetary Fact Sheets

Notes on the factsheets - definitions of parameters, units, notes on sub- and superscripts, etc.
Author/Curator:
Dr. David R. Williams, [email protected]
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258


NASA Official: Ed Grayzeck, [email protected]
Last Updated: 27 September 2018, DRW