Neptune

NeptunianAtmosphere of NeptuneNeptune-masseighth planetHistory of NeptuneLeverrier's planetNNeptunNeptune-sizedNeptunus
Neptune is the eighth and farthest known planet from the Sun in the Solar System.wikipedia
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Uranus

Uranian34 TauriMagnetosphere of Uranus
Neptune is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbour Uranus. Neptune, like Uranus, is an ice giant, a subclass of giant planet, because they are smaller and have higher concentrations of volatiles than Jupiter and Saturn.
Uranus is similar in composition to Neptune, and both have bulk chemical compositions which differ from that of the larger gas giants Jupiter and Saturn.

Solar System

outer Solar Systeminner Solar Systemouter planets
Neptune is the eighth and farthest known planet from the Sun in the Solar System.
The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane.

John Couch Adams

AdamsAdams, John CouchJ. C. Adams
The position of Neptune was subsequently calculated from Bouvard's observations, independently, by John Couch Adams and Urbain Le Verrier after his death.
His most famous achievement was predicting the existence and position of Neptune, using only mathematics.

Moons of Neptune

moon of Neptune14satellite of Neptune
Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining known 13 moons were located telescopically until the 20th century.
Neptune has 14 known moons, which are named for minor water deities in Greek mythology.

Triton (moon)

TritonAndvari Triton
Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining known 13 moons were located telescopically until the 20th century.
Triton is the largest natural satellite of the planet Neptune, and the first Neptunian moon to be discovered.

Planet

planetsFormer classification of planetsplanemo
Neptune is the eighth and farthest known planet from the Sun in the Solar System. Heinrich d'Arrest, a student at the observatory, suggested to Galle that they could compare a recently drawn chart of the sky in the region of Le Verrier's predicted location with the current sky to seek the displacement characteristic of a planet, as opposed to a fixed star.
In order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune.

Urbain Le Verrier

Le VerrierLeverrierUrbain Jean Joseph Le Verrier
The position of Neptune was subsequently calculated from Bouvard's observations, independently, by John Couch Adams and Urbain Le Verrier after his death.
Urbain Jean Joseph Le Verrier FRS (FOR) HFRSE (11 March 1811 – 23 September 1877) was a French astronomer and mathematician who specialized in celestial mechanics and is best known for predicting the existence and position of Neptune using only mathematics.

Voyager 2

2Voyager IIMariner 12
Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989.
Part of the Voyager program, it was launched 16 days before its twin, Voyager 1, on a trajectory that took longer to reach Jupiter and Saturn but enabled further encounters with Uranus and Neptune.

Giant planet

Jovian planetgiant planetsJovian
In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune, like Uranus, is an ice giant, a subclass of giant planet, because they are smaller and have higher concentrations of volatiles than Jupiter and Saturn.
There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune.

Great Dark Spot

holes in the atmosphereanticyclone storm systemNeptune
For example, at the time of the Voyager 2 flyby in 1989, the planet's southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter.
The Great Dark Spot (also known as GDS-89, for Great Dark Spot - 1989) was one of a series of dark spots on Neptune similar in appearance to Jupiter's Great Red Spot.

Ammonia

NH 3 anhydrous ammonialiquid ammonia
Like Jupiter and Saturn, Neptune'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.
Ammonia is also found throughout the Solar System on Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, among other places: on smaller, icy bodies such as Pluto, ammonia can act as a geologically important antifreeze, as a mixture of water and ammonia can have a melting point as low as 173 K if the ammonia concentration is high enough and thus allow such bodies to retain internal oceans and active geology at a far lower temperature than would be possible with water alone.

Astronomical symbols

astronomical symbolastronomicalastronomy
It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident.
Several symbols were proposed for Neptune to accompany the suggested names for the planet.

Ice giant

ice giantsice giant planetice giant planets
However, similar to Uranus, its interior is primarily composed of ices and rock; Uranus and Neptune are normally considered "ice giants" to emphasise this distinction. Neptune, like Uranus, is an ice giant, a subclass of giant planet, because they are smaller and have higher concentrations of volatiles than Jupiter and Saturn.
There are two ice giants in the Solar System: Uranus and Neptune.

George Biddell Airy

George AiryAirySir George Biddell Airy
He requested extra data from Sir George Airy, the Astronomer Royal, who supplied it in February 1844.
His reputation has been tarnished by allegations that, through his inaction, Britain lost the opportunity of priority in the discovery of Neptune.

James Challis

Challis, JamesProfessor Challis
In June 1846, upon seeing Le Verrier's first published estimate of the planet's longitude and its similarity to Adams's estimate, Airy persuaded James Challis to search for the planet.
He is best remembered for his missed opportunity to discover the planet Neptune in 1846.

Orbit

orbitsorbital motionplanetary motion
In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbour Uranus.
In a dramatic vindication of classical mechanics, in 1846 Urbain Le Verrier was able to predict the position of Neptune based on unexplained perturbations in the orbit of Uranus.

Heinrich Louis d'Arrest

Heinrich d'ArrestH. d'ArrestHeinrich Ludwig d'Arrest
Heinrich d'Arrest, a student at the observatory, suggested to Galle that they could compare a recently drawn chart of the sky in the region of Le Verrier's predicted location with the current sky to seek the displacement characteristic of a planet, as opposed to a fixed star.
While still a student at the University of Berlin, d'Arrest was party to Johann Gottfried Galle's search for Neptune.

Alexis Bouvard

BouvardBouvard, Alexis
In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbour Uranus. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet.
The position of Neptune was subsequently calculated from Bouvard's observations, independently, by John Couch Adams and Urbain Le Verrier after his death.

Planetary flyby

flybyflybysflew by
Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989.

Trident

tridentsforkgig
It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident.
The glyph or sigil of the planet Neptune, which alludes to the trident, is used in astronomy and astrology.

Saturn

Atmosphere of SaturnOrbit of SaturnPhainon
Neptune, like Uranus, is an ice giant, a subclass of giant planet, because they are smaller and have higher concentrations of volatiles than Jupiter and Saturn.
Wind speeds on Saturn can reach 1800 km/h, higher than on Jupiter, but not as high as those on Neptune.

Great Red Spot

Jupiter's red spotGRSJupiter's upper atmosphere
For example, at the time of the Voyager 2 flyby in 1989, the planet's southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter.
There is also a feature in the atmosphere of Neptune also called the Great Dark Spot.

Galileo Galilei

GalileoGalileanGalilei
Some of the earliest recorded observations ever made through a telescope, Galileo's drawings on 28 December 1612 and 27 January 1613 contain plotted points that match up with what is now known to be the position of Neptune.
Galileo also observed the planet Neptune in 1612.

Jupiter

JovianGioveplanet Jupiter
Neptune's mass of 1.0243 kg is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter.
Based on spectroscopy, Saturn is thought to be similar in composition to Jupiter, but the other giant planets Uranus and Neptune have relatively less hydrogen and helium and relatively more ices and are thus now termed ice giants.

Refracting telescope

refractorrefractor telescopeGalilean telescope
Meanwhile, Le Verrier by letter urged Berlin Observatory astronomer Johann Gottfried Galle to search with the observatory's refractor.
Some famous discoveries using achromats are the planet Neptune and the Moons of Mars.