Neptune is the outermost planet of the Jovian planets. Similar to Uranus, its atmosphere is composed of hydrogen, helium and methane. Neptune is discovered by Johann Gottfried Galle in September 23, 1846.

Although Neptune's atmosphere is similar to that of Uranus, its wind speed is not as strong. Its color is more bluish than Uranus because it has more methane in its upper atmosphere. Similar to Jupiter, it has a Great Dark Spot. The spot is about the size of Earth and the clouds are moving in an eastern direction.

Neptune has 4 faint rings. The rings are made up of dust particles that may be caused by meteorites or comets crashing into the moons.
Neptune Statistics:

Mass (kg): 1.02x1026
Diameter (km): 49528
Average Density (kg/m3): 1640
Escape Velocity (m/sec): 23300
Rotation Period (Earth days): 19.1
Tilt of Axis (o): 29.6
Orbit inclination (o): 1.77
Average Surface Temperature (oF): -353
Atmospheric Components: 85% Hydrogen, 13% Helium, 2% Methane
Number of Satellites: 8 (Despina, Galatea, Larissa, Naiad, Nereid, Proteus, Thalassa, Triton)
Number of Rings: 11 (1989N3R, 1989N2R, 1989N4R, 1989N1R)

The Structure of Neptune


Neptune's Satellites

MoonRadius
(km)		Mass
(kg)		Distance
(km)		DiscovererDate
Naiad29?48,000Voyager 21989
Thalassa40?50,000Voyager 21989
Despina74?52,500Voyager 21989
Galatea79?62,000Voyager 21989
Larissa104x89?73,600Voyager 21989
Proteus200?117,600Voyager 21989
Triton1,3502.14e+22354,800W. Lassell1846
Nereid170?5,513,400G. Kuiper1949


Neptune's Rings

NameDistance (km)Width (km)Thickness (km)Mass
1989N3R41,90015??
1989N2R53,20015??
1989N4R53,2005,800??
1989N1R62,930< 50??


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