Neptune

Properties:

Mass: 1.024 * 10²⁶ kg

Mean Radius: 24,622 km

Semi-major Axis: 30.07 AU

Orbital Period: 164.8 years

Rotational Period: 16 h 6 m 36 s

Surface Gravity: 11.15 m/(s²)

Etymology: Neptune(Roman God of the Sea)

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Neptune is the 8th and final planet from the Sun in our Solar System. Because of how far it is from the Sun, we can't actually see Neptune through our naked eye so it was discovered through mathematical analysis of the orbit of Uranus, not through observation, unlike every other planet in the Solar System. Just like Jupiter and Saturn, the two gas giants in the Solar System, Neptune has an atmosphere mainly composed of hydrogen and helium, with traces of hydrocarbons(especially methane) and potentially nitrogen. However, there are significant traces of ices in its atmosphere, too, like water and ammonia. Neptune also contains ices in its interior just like Uranus, classifying it as an "ice giant".

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Neptune has an extremely cold upper atmosphere, with temperatures reaching about 55 K(-218 C). However, the Neptunian surface is about 5400 K(5127 C).

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Neptune is characterized by extremely intense storms, just like the other 3 planets beyond the Asteroid Belt, as winds approach 600 m/s in speed at times. When the Voyager 2 Spacecraft flew by Neptune in 1989, it discovered a Great Dark Spot resembling Jupiter's Great Red Spot. This Great Dark Spot is just like Jupiter's in that it's an anticyclonic storm that is extremely intense and pressurizing.

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Neptune does hold a planetary ring system but it is nowhere near as large or noticeable as Saturn's ring system. This ring system is mainly made up of ice particles coated with silicates and carbon-based material.