Neptune


NeptuneNeptune is the eighth planet in order of distance from the Sun and the fourth one for dimensions.

Neptune was discovered in 1846 by J.G. Galls, thanks to the calculations on the perturbations of the Uranus' orbit performed independently by J.C. Adams and U. Le Verrier.

The planet is wound by an atmosphere of green-blue color, composed by hydrogen, methane and acetylene. Such atmosphere shows a structure with bands parallel to the equator, interrupted by some darkest spots, which correspond to rotatory perturbations ample to 10.000 km, and by clear cloudy formations along the parallels at high altitude. The temperature of the surface is probably about -220°C.

Thanks to the probe Voyager 2, that approached Neptune in 1989, a magnetic field was individualized, whose axis is inclinated of 50° in comparison to the axis of rotation, and three rings of dusts were discovered.

Neptune is the center of a system of eight satellites.

Average distance
from the Sun
4.496.600.000 km
Longest distance
from the Sun
4.537.000.000 km
Shortest distance
from the Sun
4.456.000.000 km
Period of revolution164,8 years
Period of rotation16 hours, 5'
Average
orbital velocity
5,4 km/s
Inclination of the axis28° 48'
Inclination of the orbit
compared to the ecliptic
1,8°
Eccentricity
of the orbit
0,009
Equatorial ray24.750 km
Deflection0,02
Mass1,06 x 10^26 kg
Density1,76 kg/dm³
Albedo0,53


Neptune's satellites

NameAverage
distance (km)
Ray
(km)
Orbital
period (days)
Author and year
of discovery
Naiadedistance < 300.000 km

ray < 200 km

discovered by Voyager 2 in 1989-90

Thalassa
Despoina
Galatea
Larissa
Proteo
Triton355.0001.3805,88Lassell, 1846
Nereide5.510.000250359,40Kuiper, 1949


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