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Neptune: Facts & Figures
Discovered By
Johann Galle
Date of Discovery
1846
Average Distance from the Sun
Metric: 4,498,252,900 km
English: 2,795,084,800 miles
Scientific Notation: 4.4982529 x 109 km (30.069 A.U.)
By Comparison: 30.069 x Earth
Perihelion (closest)
Metric: 4,459,630,000 km
English: 2,771,087,000 miles
Scientific Notation: 4.45963 x 109 km (29.811 A.U.)
By Comparison: 29.820 x Earth
Aphelion (farthest)
Metric: 4,536,870,000 km
English: 2,819,080,000 miles
Scientific Notation: 4.53687 x 109 km (30.327 A.U.)
By Comparison: 30.326 x Earth
Equatorial Radius
Metric: 24,764 km
English: 15,388 miles
Scientific Notation: 2.4764 x 105 km
By Comparison: 3.883 x Earth
Equatorial Circumference
Metric: 155,597 km
English: 96,683 miles
Scientific Notation: 1.55597 x 105 km
Volume
Metric: 62,526,000,000,000 km3
Scientific Notation: 6.2526 x 1013 km3
By Comparison: 57.7 x Earth's
Mass
Metric: 102,440,000,000,000,000,000,000,000 kg
Scientific Notation: 1.0244 x 1026 kg
By Comparison: 17.147 x Earth's
Density
Metric: 1.76 g/cm3
By Comparison: 0.317 x Earth
Surface Area
Metric: 7,640,800,000 km2
English: 2,950,100,000 square miles
Scientific Notation: 7.6408 x 109 km2
By Comparison: 14.980 x Earth
Equatorial Surface Gravity
Metric: 10.71 m/s2
English: 35.14 ft/s2
By Comparison: If you weigh 100 pounds on Earth, you would weigh 110 pounds on Neptune.
Escape Velocity
Metric: 85,356 km/h
English: 53,038 mph
Scientific Notation: 23,710 m/s
By Comparison: Escape velocity of Earth is 25,022 mph.
Sidereal Rotation Period (Length of Day)
0.67125 Earth days
16.11 hours
By Comparison: 0.673 x Earth
Sidereal Orbit Period (Length of Year)
164.79 Earth years
60,190 Earth days
Mean Orbit Velocity
Metric: 19,720 km/h
English: 12,253 mph
Scientific Notation: 5,477.8 m/s
By Comparison: 0.490 x Earth
Orbital Eccentricity
.00859
By Comparison: 0.514 x Earth
Orbital Inclination to Ecliptic
1.769 degrees
Equatorial Inclination to Orbit
29.58 degrees
By Comparison: 1.261 x Earth
Orbital Circumference
Metric: 28,142,000,000 km
English: 17,487,000,000 miles
Scientific Notation: 2.8142 x 1010 km
By Comparison: 30.44 x Earth
Effective Temperature
Metric: -214 °C
English: -353 °F
Scientific Notation: 59 K
Atmospheric Constituents
Hydrogen, Helium, Methane
Scientific Notation: H2, He, CH4
By Comparison: Earth's atmosphere consists mostly of N2 and O2.
Neptune's Moons
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