This chart shows the differences between Neptune and Earth. To change the planets/moons being compared, change one or more of the form fields at the bottom and click Refresh.

	Neptune	Earth
Discovered By	Johann Galle	Known by the Ancients
Date of Discovery	1846	Unknown
Average Orbit Distance	4,498,252,900 km	149,597,890 km
Perihelion (closest)	4,459,630,000 km	147,100,000 km
Aphelion (farthest)	4,536,870,000 km	152,100,000 km
Equatorial Radius	24,764 km	6,378.14 km
Equatorial Circumference	155,597 km	40,075 km
Volume	62,526,000,000,000 km3	1,083,200,000,000 km3
Mass	102,440,000,000,000,000,000,000,000 kg	5,973,700,000,000,000,000,000,000 kg
Density	1.76 g/cm3	5.515 g/cm3
Surface Area	7,640,800,000 km2	510,065,700 km2
Equatorial Surface Gravity	10.71 m/s2	9.766 m/s2
Escape Velocity	85,356 km/h	40,248 km/h
Rotation Period (Length of Day)	0.67125 sidereal days	0.99726968 sidereal days
Orbit Period (Length of Year)	164.79 sidereal years	1.0000174 sidereal years
Mean Orbit Velocity	19,720 km/h	107,229 km/h
Orbit Eccentricity	.00859	0.01671022
Orbital Inclination to Ecliptic	1.769 degrees	0.00005 degrees
Equatorial Inclination to Orbit	29.58 degrees	23.45 degrees
Orbital Circumference	28,142,000,000 km	924,375,700 km
Atmospheric Constituents	Hydrogen, Helium, Methane	Nitrogen, Oxygen

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