CHARACTERISTICS OF NEPTUNE

Characteristics	Values
Semi-major axis in astronomical units (ua)	30.11039
Semi-major axis in km	4 504 449 759
Eccentricity of the orbit	0.00946
Inclination of the orbit on the ecliptic	1°.770
Inclination of the equator on the ecliptic	28°.31
Sidereal period of revolution	164 years and 281.3 days
Rotation period	16.11 hours
Orbital velocity	5.5 km/s
Apparent equatorial diameter at the smallest distance from the Earth (maximum value)	2".4
Equatorial diameter (Earth=1)	3.8826
Equatorial diameter	49 528 km
Visual magnitude at the opposition	7.84
Flattening	1/59
Volume (Earth=1)	57.5
Mass (Sun=1)	1/19 416.30
Mass (Earth=1)	17.15
Mass Neptune+satellites (Sun=1)	1/19 412.24
Mass Neptune+satellites (Neptune=1)	1.0002
Density (Earth=1)	0.30
Density (water=1)	1.64
Gravity at the surface (Earth=1)	1.14
Escape velocity	23 500 m/s
Reflectivity (geometric albedo)	0.41
The highest peak	14 000 m
Deepest pit	0 m
Cloud temperature	-225°C
Atmosphere	hydrogen 74%, helium 25%, methane 1%

Credit : NASA/JPL

Neptune seen by Voyager from a distance of 13 millions km: notice the blue spot, a tornado similar to the red spot of Jupiter.