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User:Amit6/infneptune

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Neptune
Neptune from Voyager 2
Neptune from Voyager 2
Discovery
Discovered byUrbain Le Verrier
John Couch Adams
Johann Galle
Discovery dateSeptember 23, 1846[1]
Designations
AdjectivesNeptunian
SymbolAstronomical symbol for Neptune.
Orbital characteristics[2][3]
Epoch J2000
Aphelion4,553,946,490 km
30.44125206 AU
Perihelion4,452,940,833 km
29.76607095 AU
4,503,443,661 km
30.10366151 AU
Eccentricity0.011214269
60,190[4] days
164.79 years
367.49 day[5]
5.43 km/s[5]
267.767281°
Inclination1.767975°
6.43° to Sun's equator
131.794310°
265.646853°
Known satellites13
Physical characteristics
Equatorial radius
24,764 ± 15 km[6][7]
3.883 Earths
Polar radius
24,341 ± 30 km[6][7]
3.829 Earths
Flattening0.0171 ± 0.0013
7.6408×109 km²[4][7]
14.98 Earths
Volume6.254×1013 km³[5][7]
57.74 Earths
Mass1.0243×1026 kg[5]
17.147 Earths
Mean density
1.638 g/cm³[5][7]
11.15 m/s²[5][7]
1.14 g
23.5 km/s[5][7]
0.6713 day[5]
16 h 6 min 36 s
Equatorial rotation velocity
2.68 km/s
9,660 km/h
28.32°[5]
North pole right ascension
19h 57m 20s[6]
North pole declination
42.950°[6]
Albedo0.290 (bond)
0.41 (geom.)[5]
Surface temp. min mean max
1 bar level 72 K[5]
0.1 bar (10 kPa) 55 K[5]
8.0 to 7.78[5][8]
2.2–2.4″[5][8]
Atmosphere[5]
19.7 ± 0.6 km
Composition by volume
80±3.2%Hydrogen (H2)
19±3.2%Helium
1.5±0.5%Methane
~0.019%Hydrogen deuteride (HD)
~0.00015%Ethane
Ices:
Ammonia
Water
Ammonium hydrosulfide(NH4SH)
Methane (?)
  1. ^ Hamilton, Calvin J. (August 4, 2001). "Neptune". Views of the Solar System. Retrieved 2007-08-13.
  2. ^ Yeomans, Donald K. (July 13, 2006). "HORIZONS System". NASA JPL. Retrieved 2007-08-08.—At the site, go to the "web interface" then select "Ephemeris Type: ELEMENTS", "Target Body: Neptune Barycenter" and "Center: Sun".
  3. ^ Orbital elements refer to the barycentre of the Neptune system, and are the instantaneous osculating values at the precise J2000 epoch. Barycentre quantities are given because, in contrast to the planetary centre, they do not experience appreciable changes on a day-to-day basis from to the motion of the moons.
  4. ^ a b Cite error: The named reference fact2 was invoked but never defined (see the help page).
  5. ^ a b c d e f g h i j k l m n o Williams, David R. (September 1, 2004). "Neptune Fact Sheet". NASA. Retrieved 2007-08-14.
  6. ^ a b c d P. Kenneth, Seidelmann (2007). "Report of the IAU/IAGWorking Group on cartographic coordinates and rotational elements". Celestial Mechanics and Dynamical Astronomy. 90. Springer Netherlands: 155–180. doi:10.1007/s10569-007-9072-y. Retrieved 2008-03-07. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. ^ a b c d e f g Refers to the level of 1 bar (100 kPa) atmospheric pressure
  8. ^ a b Cite error: The named reference ephemeris was invoked but never defined (see the help page).