uranus

Uranus

Uranus, as seen by Voyager 2
Discovery
Discovered by	William Herschel
Discovery date	March 13, 1781
Designations
Adjective	Uranian
Orbital characteristics[1][a]
Epoch J2000
Aphelion	3 004 419 704 km 20.083 305 26 AU
Perihelion	2 748 938 461 km 18.375 518 63 AU
Semi-major axis	2 876 679 082 km 19.229 411 95 AU
Eccentricity	0.044 405 586
Orbital period	30 799.095 days 84.323 326 yr
Synodic period	369.66 days[2]
Average orbital speed	6.81 km/s[2]
Mean anomaly	142.955 717°
Inclination	0.772 556° 6.48° to Sun's equator
Longitude of ascending node	73.989 821°
Argument of perihelion	96.541 318°
Satellites	27
Physical characteristics
Equatorial radius	25 559 ± 4 km 4.007 Earths[3][c]
Polar radius	24 973 ± 20 km 3.929 Earths[3][c]
Flattening	0.022 9 ± 0.000 8[b]
Surface area	8.115 6×109 km²[4][c] 15.91 Earths
Volume	6.833×1013 km³[2][c] 63.086 Earths
Mass	(8.6810 ± 0.0013)×1025 kg 14.536 Earths[5] GM=5 793 939 ± 13 km³/s²
Mean density	1.27 g/cm³[2][c]
Equatorial surface gravity	8.69 m/s²[2][c] 0.886 g
Escape velocity	21.3 km/s[2][c]
Sidereal rotation period	−0.718 33 day 17 h 14 min 24 s[3]
Equatorial rotation velocity	2.59 km/s 9,320 km/h
Axial tilt	97.77°[3]
North pole right ascension	17 h 9 min 15 s 257.311°[3]
North pole declination	−15.175°[3]
Albedo	0.300 (bond) 0.51 (geom.)[2]
Surface temp. 1 bar level[7] 0.1 bar (tropopause)[8]	min mean max 76 K 49 K 53 K 57 K
Apparent magnitude	5.9[6] to 5.32[2]
Angular diameter	3.3"–4.1"[2]
Atmosphere[8][9][10][d]
Scale height	27.7 km[2]
Composition	(Below 1.3 bar) 83 ± 3% Hydrogen (H2) 15 ± 3% Helium 2.3% Methane 0.009% (0.007–0.015%) Hydrogen deuteride (HD)[11] Ices: Ammonia water ammonium hydrosulfide (NH4SH) methane (CH4)