Astronomy Planets - Neptune Bulk Parameters | Orbital Parameters Observational Parameters | Atmospheric Parameters Satellites Bulk Parameters Mass 102.43 × 1024 kg Volume 6 254 × 1010 km3 Equatorial Radius (Defined by Pressure = 1 bar) 24 766 km Polar Radius (Defined by Pressure = 1 bar) 24 342 km Volumetric Mean Radius 24 624 km Ellipticity 0.017 1 Mean Density 1 638 kg m-3 Surface Gravity (At Pressure = 1 bar) 11.00 m s-2 Escape Velocity 23.5 km s-1 GM 6.8351 × 106 km3 s-2 Bond Albedo 0.82 Visual Geometric Albedo 0.41 Visual Magnitude -6.87 Solar Irradiance 1.47 W m-2 Black-Body Temperature 33.2 K Orbital Parameters Semimajor Axis 4 498.3 × 106 km Sidereal Orbit Period 60 189.0 days Tropical Orbit Period 59 799.9 days Perihelion 4 458.0 × 106 km Aphelion 4 535.2 × 106 km Synodic Period 367.49 days Mean Orbital Velocity 5.48 km s-1 Orbital Inclination 1.769 ° Orbital Eccentricity 0.008 59 Sidereal Rotation Period (Magnetic Coordinates, determined by Voyager 2 Radio Science Experiment) 16.11 hours Obliquity to Orbit 29.56 ° Observational Parameters Maximum Apparent Diameter from Earth 2.4 arc seconds Minimum Apparent Diameter from Earth 2.2 arc seconds Maximum Distance from Earth 4 687.3 × 106 km Minimum Distance from Earth 4 305.9 × 106 km Apparent Magnitude near Opposition 7.8 Atmospheric Parameters Surface Pressure Much more than 100 bars Average Temperature about 58 K Temperature at 1 bar about 72 K Density at 1 bar about 0.45 kg m-3 Scale Height 19.1 km to 20.3 km Wind Speeds 0 to 200 m s-1 Mean Molecular Weight 2.53 g mol-1 to 2.69 g mol-1 Molecular Hydrogen H2 80% Helium He 19% Methane CH4 1.5% Hydrogen Deuteride HD 105 ppm Ethane C2H6 1.5 ppm Ammonia Ice Water Ice Ammonia Hydrosulphide Methane Ice Satellites Naiad Larissa Thalassa Proteus Despina Triton Galatea Nereid

Page compiled: Wed Sep 05 18:38:01 GMT+01:00 2001