This is the place to find information on the planet, Neptune. Enjoy!

Neptunian Bulk Parameters
Mass: (1.02 x 1024 kg)
Volume: (6.253 x 1010 km3)
Diameter: 49528 km
Mean Density: 1638 kg/m3
Gravity: 11 m/s2 (eq., 1 bar)
Escape Velocity: 23.5 km/s

Neptunian Atmosphere
Surface Pressure: 100 bars
Average Temperature: 58 k
Density At 1 Bar: 0.45 kg/m3
Wind speeds: 0-2000 km/h
Scale Height: 19.1-20.3 km
Mean Molecular Weight: 2.53-2.69 g/mole
Atmospheric composition
Major: Molecular hydrogen (H2)- 80.0% (3.2%); Helium (He)- 19.0% (3.2%); Methane (CH4) 1.5% (0.5%)
Minor: Hydrogen Deuteride (HD)- 192; Ethane (C2H6)- 1.5
Aerosols: Ammonia ice, water ice, ammonia hydrosulfide, methane ice(?)

Neptune is a similar planet to Uranus, though it is not tipped over on its side and is a little smaller than Uranus. A day on Neptune lasts sixteen hours and three minutes, less than a day on Earth. Neptune is about 2.8 billion miles (4.5 billion km) away from the Sun, so it takes about 165 Earth years to circle the Sun once.

Like a typical gas planet, Neptune has rapid winds confined to bands of latitude and large storms or vortices. Neptune's winds are the fastest in the solar system, reaching 2000 km/hour. Like Jupiter and Saturn, Neptune has an internal heat source -- it radiates more than twice as much energy as it receives from the Sun. Neptune's magnetic field is, like Uranus', oddly oriented and probably generated by motions of conductive material (probably water) in its middle layers.

After the discovery of Uranus, astronomers noticed that the orbit of Uranus was irregular and was not in compliance with Newton's Laws. Basically, Uranus did not move as it was expected. They thought that it was being pulled out of its orbit by something further from the Sun, possibly by another attractive force, possibly another undiscovered planet. In the early 1800's, two young astronomers, John Couch Adams in England and Urbain Leverrier in France, seperately worked out where this force is situated.

Neptune was first observed and discovered by Johann Galle of Berlin, Germany on September 23, 1846 very near to the locations independently predicted by Adams and Leverrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. They are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Leverrier diverge from Neptune's actual orbit fairly quickly. If the search took place years later, then Neptune would have never been discovered.

The only spacecraft that has visited Neptune was Voyager 2 on August 25, 1989. From this encounter comes all of Earth's knowledge of Neptune.

Neptune has eight discovered moons. Their names are: Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, and Nereid.

Triton, Neptune's biggest and most important moon, was discovered by a man named Lassell, in 1846. It is situated 220,593 miles (355,000 km) away from Neptune, and is 1,690 miles (2,720 km) in diameter.

All of these moons excluding Triton and Nereid were discovered by Voyager 2, which holds most of Earth's knowledge of Neptune.


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