Uranus

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Taken from: Wikipedia

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Uranus

Uranus presented a featureless disk to Voyager 2 in 1986. Its appearance reflects the presence of a high-altitude hydrocarbon photochemical haze overlying clouds of methane, which in turn overlie clouds of hydrogen sulfide and/or ammonia (below these are additional unseen cloud decks of different compositions). The blue-green coloration results from the absorption bands of methane.
Discovery
Discovered by	William Herschel
Discovery date	March 13, 1781
Designations
Pronunciation	i/ˈjʊərənəs/ or i/jʊˈreɪnəs/[1][2]
Adjective	Uranian
Orbital characteristics[6][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 42,718 Uranus solar days[3]
Synodic period	369.66 days[4]
Average orbital speed	6.81 km/s[4]
Mean anomaly	142.955 717°
Inclination	0.772 556° to Ecliptic 6.48° to Sun's equator 1.02° to Invariable plane[5]
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[7][b]
Polar radius	24,973 ± 20 km 3.929 Earths[7][b]
Flattening	0.022 9 ± 0.000 8[c]
Circumference	159,354.1 km[8]
Surface area	8.115 6×109 km2[8][b] 15.91 Earths
Volume	6.833×1013 km3[4][b] 63.086 Earths
Mass	(8.6810 ± 0.0013)×1025 kg 14.536 Earths[9] GM=5 793 939 ± 13 km3/s2
Mean density	1.27 g/cm3[4][b]
Equatorial surface gravity	8.69 m/s2[4][b] 0.886 g
Escape velocity	21.3 km/s[4][b]
Sidereal rotation period	0.718 33 day (Retrograde) 17 h 14 min 24 s[7]
Equatorial rotation velocity	2.59 km/s 9,320 km/h
Axial tilt	97.77°[7]
North pole right ascension	17 h 9 min 15 s 257.311°[7]
North pole declination	−15.175°[7]
Albedo	0.300 (Bond) 0.51 (geom.)[4]
Surface temp. min mean max 1 bar level[11] 76 K 0.1 bar (tropopause)[12] 49 K 53 K 57 K
Apparent magnitude	5.9[10] to 5.32[4]
Angular diameter	3.3"–4.1"[4]
Atmosphere[12][14][15][d]
Scale height	27.7 km[4]
Composition	(Below 1.3 bar) 83 ± 3% hydrogen (H2) 15 ± 3% helium (He) 2.3% methane (CH4) 0.009% (0.007–0.015%) hydrogen deuteride (HD)[13] Ices: ammonia (NH3) water (H2O) ammonium hydrosulfide (NH4SH) methane ice (?) (CH4•5.75H2O)