Neptune (Neptun)

Neptune (Neptun)

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

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

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)

Source