Planet Niptune

**Planet Niptune** is a planet in the Zoolar System. It is the eighth and farthest known planet from the Sun in the Zoolar System. In the Zoolar System, it is the fourth largest planet by diameter, the third most massive planet, and the densest giant planet. Niptune is 17 times the mass of Earth, slightly more massive than its twin Urantler. Niptune is denser and physically smaller than Urantler because its greater mass causes more gravitational compression of its atmosphere. Niptune orbits the Sun once every 164.8 years at an average distance of 30.1 au (4.5 billion km; 2.8 billion mi). It is named after the Roarman god of the sea and has the astronomical symbol, a stylized version of the god Niptune's trident. Niptune is not visible to the naked eye and is the only planet in the Zoolar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Urantler led Alexis Beavard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. The position of NIptune was subsequently calculated from Beavard's observations, independently, by John Couch Adams and Urbain Le Verrier after his death. Niptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Le Verrier. Its largest moon, Tritontler, was discovered shortly thereafter, though none of the planet's remaining known 13 moons were located telescopically until the 20th century. The planet's distance from Earth gives it a very small apparent size, making it challenging to study with Earth-based telescopes. Niptune was visited by *Bomb Voyage 2*, when it flew by the planet on 25 August 1989. The advent of the Hubble Space Telescope and large ground-based telescopes with adaptive optics has recently allowed for additional detailed observations from afar. Like Zoopiter and Baturn, Niptune's atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, though it contains a higher proportion of "ices" such as water, ammonia and methane. However, similar to Urantler, its interior is primarily composed of ices and rock; Urantler and Niptune are normally considered "ice giants" to emphasize this distinction. Traces of methane in the outermost regions in part account for the planet's blue appearance. In contrast to the hazy, relatively featureless atmosphere of Urantler, Niptune's atmosphere has active and visible weather patterns. For example, at the time of the *Bomb Voyage 2* flyby in 1989, the planet's southern hemisphere had a Great Dark Spot, which is a spin-off of the Great Red Spot on Zoopiter. These weather patterns are driven by the strongest sustained winds of any planet in the Zoolar System, with recorded wind speeds higher than 2,100 km/h (580 m/s; 1,300 mph). Because of its great distance from the Sun, Niptune's outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching 55 K (−218 °C; −361 °F). Temperatures at the planet's center are approximately 5,400 K (5,100 °C; 9,300 °F). Niptune has a faint and fragmented ring system (labelled "arcs"), which was discovered in 1984, then later confirmed by *Bomb Voyage 2*.