Neptune

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Taken from: Wikipedia

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Neptune

Neptune from Voyager 2 with Great Dark Spot at left and Small Dark Spot at lower right. White clouds are composed of methane ice; overall blue coloration is due at least in part to methane absorption of red light.
Discovery
Discovered by	Urbain Le Verrier Johann Galle
Discovery date	23 September 1846[1]
Designations
Pronunciation	i/ˈnɛptjuːn/[2]
Adjective	Neptunian
Orbital characteristics[7][a]
Epoch J2000
Aphelion	4,553,946,490 km 30.44125206 AU
Perihelion	4,452,940,833 km 29.76607095 AU
Semi-major axis	4,503,443,661 km 30.10366151 AU
Eccentricity	0.011214269
Orbital period	60,190.03[3] days 164.79 years 89,666 Neptune solar days[4]
Synodic period	367.49 days[5]
Average orbital speed	5.43 km/s[5]
Mean anomaly	267.767281°
Inclination	1.767975° to Ecliptic 6.43° to Sun’s equator 0.72° to Invariable plane[6]
Longitude of ascending node	131.794310°
Argument of perihelion	265.646853°
Satellites	14
Physical characteristics
Equatorial radius	24,764 ± 15 km[8][b] 3.883 Earths
Polar radius	24,341 ± 30 km[8][b] 3.829 Earths
Flattening	0.0171 ± 0.0013
Surface area	7.6183×109 km2[3][b] 14.98 Earths
Volume	6.254×1013 km3[5][b] 57.74 Earths
Mass	1.0243×1026 kg[5] 17.147 Earths 5.15×10−5 Suns
Mean density	1.638 g/cm3[5][b]
Equatorial surface gravity	11.15 m/s2[5][b] 1.14 g
Escape velocity	23.5 km/s[5][b]
Sidereal rotation period	0.6713 day[5] 16 h 6 min 36 s
Equatorial rotation velocity	2.68 km/s 9,660 km/h
Axial tilt	28.32°[5]
North pole right ascension	19h 57m 20s[8] 299.3°
North pole declination	42.950°[8]
Albedo	0.290 (bond) 0.41 (geom.)[5]
Surface temp. min mean max 1 bar level 72 K[5] 0.1 bar (10 kPa) 55 K[5]
Apparent magnitude	8.02 to 7.78[5][9]
Angular diameter	2.2–2.4″[5][9]
Atmosphere[5]
Scale height	19.7 ± 0.6 km
Composition	80±3.2% hydrogen (H2) 19±3.2% helium (He) 1.5±0.5% methane (CH4) ~0.019% hydrogen deuteride (HD) ~0.00015% ethane (C2H6) Ices: ammonia (NH3) water (H2O) ammonium hydrosulfide (NH4SH) methane ice (?) (CH4•5.75H2O)