Neptune (ˈnɛptuːn)

Neptune is one of two ice giant planets in the Solar System, the furthest from the Sun. It is the densest giant planet with the third-most mass and the fourth-largest diameter. Neptune, not visible to the naked eye, is the only planet in its system discovered by mathemetical predictions rather than pure observation.

Geography

Neptune's mass hangs between that of the Earth and the larger gas giants Jupiter and Saturn. Like Uranus, it is an ice giant, meaning it is smaller with a higher amount of volatiles like methane and ammonia. The internal structure itself is much like Uranus, with a mantle rich in water, ammonia, and methane, with an atmosphere containing hydrogen and helium, with enough methan to give the planet its blue hue.
Also like Uranus, the mantle is under enough pressure to break apart methane and condense its carbon into diamond crystals that rain, which also occurs on the other giant planets. The top of the mantle contains an ocean of liquid carbon with chunks of solid diamond floating within it. Also like the other giant planets, Neptune possesses a dense, solid, rocky core.

Climate

Neptune's atmosphere is predominantly hyrodgen then helium, with trace amounts of methane that make the atmosphere blue. This atmosphere has two main regions: a lower, colder troposphere, and a higher, warmer stratosphere. The troposphere is banded by coulds made of methane, ammonia, or hydrogen sulfide depending on their altitude. These clouds are visible from orbit.

History

Neptune was the last planet in the Solar System to be discovered by humans, although it was accidentally discovered and mistakenly identified as a star by Galileo Galilei in 1612-1613. It was truly discovered and identified as the eighth planet in 1846. It was visited by Voyager 2 in 1989, where it flew close enough to take pictures of its moon Triton.
Exploration began on November 30th, 2070, with Poseidon 2, which made Neptune the first planet to be explored by a manned crew through the use of the wormdrive, invented earlier that year. Astronauts aboard the Janus spacecraft, the first spacecraft capable of personal traversable wormhole creation, orbited the planet 24 times before wormholing back to Earth. This was unfortunate news to the Poseidon 1 astronauts aboard an old-fashioned Zephyr, as they were taken out of cryosleep early, in December 2070 by Poseidon 3 (another wormdrive-equipped mission). Originally supposed to be woken on January 12th, 2076 (six years later) after a 29-year journey, a far superior form of technology had been invented in the time that it took them to even reach Neptune manually. At least they could return home in time for Christmas!

Designations

Classification	Planet
Type	Ice giant
Alternative names	Sol VII
Adjective	Neptunian

Location Data

Star	Sun
Moons	14
Star System	Solar System
Spiral Arm	Orion Arm
Galaxy	Milky Way

Orbit & Rotation

Rotation period	0.67125 standard days 16h 06s 36s
Orbital period	164.8 standard years 60,195 standard days

Atmosphere

Composition by volume

79.5% hydrogen 18.5% helium 1.5% methane <1% trace gases