Uranus Fact Sheet


Voyager 2 - Uranus

Uranus/Earth Comparison


Bulk parameters

   
   Uranus   
 
   Earth   
Ratio
(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 albedo 0.300 0.306 0.980
Visual geometric albedo 0.51 0.367 1.390
Visual magnitude V(1,0) -7.19 -3.86 -
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 satellites 27 1
Planetary ring system Yes No

Orbital parameters

   
   Uranus   
 
   Earth   
Ratio
(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 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 23.44 -
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             5.5  
Maximum apparent visual magnitude             5.32   

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.
NASA
Author/Curator:
Dr. David R. Williams, dave.williams@nasa.gov
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258


NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov
Last Updated: 19 May 2016, DRW