Solar System: Planets: Neptune

Neptune was discovered on September 23, 1846, by two mathematicians: John C. Adams, a British mathematician, and Leverrier, a French mathematician. The planet is a Jovian planet, which means it's mainly gaseous. Some basic facts:

• Diameter of 49528 km
• Density of about 1600 kg/cubic meter
• Average distance from the Sun is 4497 mil. km (30 AU)
• Oribiting time of 165 years
• Composition: Hydrogen (84%), Helium (14%), Methane (2%), small rocky core covered with ammonium ice
• Rotation period of 16.1 hours (determined by Voyager II in 1989)
• Has an internal heat source
• Cloud bands and storm systems present
• A magnetic field, though weaker than that of the Earth
• 55 degree tilt of the magnetic field axis
• Three complete rings with uneven distribution of material
• Eight moons, largest of which is Triton, diameter of 2705 km, south pole has an ammonium ice cap; transient atmosphere - nitrogen, some methane; retrograde orbit.

The planet is blueish in color, which is actually visible from the Hubble Space Telescope (but hardly with a naked eye).

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