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Neptune

Neptune
Orbital Characteristics of Neptune

Orbital Characteristics

Perihelion: 4,452,940,833 km, 29.76607095 AE
Aphelion: 4,553,946,490 km, 30.44125206 AE
Semi-major axis: 4,503,443,661 km, 30.10366151 AE
Eccentricity: 0.011214269
Orbital period: 60,190 days, 164.79 years
Synodic period: 367.49 days
Average orbital speed: 5.43 km/s
Mean anomaly: 267.767281°
Inclination: 1.767975°
Longitude of ascending node: 131.794310°
Argument of perihelion: 265.646853°

Satellites/moons: 13 (Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, Nereid, Halimede, Sao, Laomedeia, Psamathe, Neso)

Physical Characteristics of Neptune

Physical Characteristics

Equatorial radius: 24,764 km (3.883 x Earth)
Flattening: 0.0171 ± 0.0013
Surface area: 7.6408×109 km2 (14.98 x Earth)
Volume: 6.254×1013 km3 (57.74 x Earth)
Mass: 1.0243×1026 kg (17.147 x Earth)
Mean density: 1.638 g/cm3
Equatorial surface gravity: 11.15 m/s2
Escape velocity: 23.5 km/s
Sidereal rotation period: 0.6713 day Earth days, 16 h 6 min 36 s Earth hours
Axial tilt : 28.32°
Albedo: 0.41
Average surface temperatures: 59 K, -214 °C, -353 °F
Apparent magnitude: 8.0 to 7.78
Angular diameter: 2.2″ - 2.4″
The Atmosphere of Neptune

The Atmosphere

Composition:
  • 80±3.2% Molecular Hydrogen (H2)
  • 19±3.2% Helium
  • 1.5±0.5% Methane (CH4)
  • 192 ppm Hydrogen Deuteride (HD)
  • 1.5 ppm Ethane (C2H6)

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