Neptune is the small blue disk that can be seen from Earth. It is the 8th planet from the Sun and is called the "Ice Giant" planet. It was Discovered on September 23, 1846 and named for the Roman God of the sea because of its blue-green color. The mass is approximately 17 times the size of Earth. It makes one full rotation every 18 hours. Neptune has many more facinating features awaiting discovery.
Neptune is one of few planets that can be compared to the Earth. Like Earth it has visible weather patterns and clouds. It is also has a tilted axis. Compared to Earth it is almost 17 times larger. Because of the increased mass it takes about 165 years to orbit the Sun.
Neptune's Diameter is 30,750 miles. It was visited by Voyager 2 on August 25, 1989. Neptune's blue color is largely the result of absorption of red light by methane in the atmosphere but there is some additional as-yet-unidentified chromophore which gives the clouds their rich blue tint.
Neptune's atmosphere is made of 79% hydrogen, 18% helium, 3% Methane, Ammonia, others. Like Saturn it has a planetary ring system. The rings consist of ice coated with silicates or carbon-based material. This combination gives them thier reddish color. The three main rings are Adams Ring, Le Verrier Ring, and Galle Ring.
Neptune was first observed on December 28, 1612 and then again on January 27, 1613. Galileo, one of its observers,would have most likely declared Neptune a planet if clouds had not covered the sky on the days after observation. Neptune has many clouds but one of its more interesting is named the Scooter. It is called this because the small dark spot in the southern hemisphere and a small irregular white cloud zip around Neptune every 16 hours. Another fascinating feature is The Great Dark Spot. It rotates about 30 degrees with every rotation, though the spot has faded it is predicted to return.
Neptune has 13 known satellites. Its biggest is named Triton. Of the 13 only 7 including Triton have been named. The other 6 are Naiad, Thalassa, Despina, Galatea, Larissa, Proteus and Nereid.
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