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Neptune


The smallest and last of the four gas giants of the Solar system, Neptune lies 30 times Earth's distance from the Sun.

Neptune's core is a ball of molten rocky material slightly larger than the Earth, with a temperature of 7,000 degrees C. This core is surrounded by a layer of water and ammonia, which is in turn surrounded by a layer of hydrogen and helium. There is an upper cloud layer of methane ice, and a lower cloud layer of hydrogen sulfide ice.

The largest of Neptune's satellites, Triton, is slightly smaller than Luna. It's rocky surface is covered with a methane frost, and there is a slight methane atmosphere. It orbits Neptune backwards.


Orbital Distance:   29.800 AU - 30.316 AU (average 30.058 AU)
Eccentricity:       0.009
Local Year:         60,190.30 days (164.8 years)
Orbital Velocity:   5.43 km/s (average)
Inclination:        1.572°
Local Day:          0.671 day (16h 6m 0s)
Axial Tilt:         28.800°

Diameter:           50,538 km (cloud tops)
Composition:        n/a
Density:            2.064 g/cm3
Mass:               1.03 x 1020 tonnes (17.20 earths)
Gravity:            1.20 G
Escape Velocity:    23.90 km/s
Area:               8,024 million km2
Surface Material:   n/a
Atmosphere:         Hydrogen, helium, and methane
Pressure:           ?
Albedo:             0.35
Temperature:        -220°C (cloud tops)

 


Satellite        Distance       Month         Day   Diameter
Naiad           48,000 km     0.296 d     0.296 d      0.004
Thalassa        50,000 km     0.312 d     0.312 d      0.006
Despina         52,500 km     0.333 d     0.333 d      0.014
Galatea         62,000 km     0.429 d     0.429 d      0.012
Larissa         73,600 km     0.554 d     0.554 d      0.015
Proteus        117,600 km     1.121 d     1.121 d      0.033
Triton         354,800 km     5.877 d     5.877 d      0.212
Nereid       5,514,000 km   360.160 d   360.160 d      0.019

 


Ring                   Distance from Neptune      Width
Galle                        41,900 km            50 km
La Verrier                   53,200 km            50 km
Plateau (or Lassell)   53,200 km - 59,100 km   4,000 km
Arago                        57,600 km            30 km
Adams                        62,900 km            50 km

 

FAQ - Astronomical Glossary


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