History UsefulNotes / Neptune

Similar to {{UsefulNotes/Uranus}}, an oddity of Neptune's magnetic field is that it is heavily tilted relative to the planet's axis, as well as off-center. This shared mystery of the ice giants remains unsolved.

Discoveries from the 1990s onward have shown just how profound an effect that Neptune has had on UsefulNotes/{{the Solar System}}'s structure. The inner boundary of the Kuiper Belt is defined by Neptune's gravity, and the scattered disk exists almost entirely because of Kuiper Belt objects that passed too close to the planet and were launched into eccentric orbits. In this way, Neptune is the most similar to Jupiter of any other planet. Some models even state that Neptune itself used to orbit closer to the Sun than Uranus but was thrown into its current one after booth their orbits were disrupted by Jupiter.

Similar to Uranus, an oddity of Neptune's magnetic field is that it is heavily tilted relative to the planet's axis, as well as off-center. This shared mystery of the ice giants remains unsolved.

Neptune has the honor of being the first planet to be discovered with mathematics as opposed to actual astronomic observation. Thus, it was not so much discovered, as ''predicted'' mathematically. Fitting, since it is the only planet that can never be observed from {{UsefulNotes/Earth}} without a telescope.[[note]]Technically, at its brightest, it might be just barely visible to the naked eye by someone with absolutely perfect vision observing from somewhere with no light pollution at all, but don't hold your breath.[[/note]] It was first spotted way back in the 1610s by Galileo, but he mistook the planet for a fixed star due to Neptune having begun its apparent retrograde motion that same day. And in 1830, 16 years before Neptune would be discovered, Sir John Herschel, son of {{UsefulNotes/Uranus}} discoverer William, observed Neptune unknowingly. When predictions for Uranus' orbit were proven to be off, it was hypothesized that another planet was exerting some gravitational force. After years of calculations, Urban Le Verrier proved Neptune's existence and told astronomers where to point their telescopes, assuring them a planet would be there for them to see. Johann Gottfried Galle, who Le Verrier sent his calculations to in the mail, found Neptune that very night after less than an hour of searching and less than a degree from the predicted position. [[UsefulNotes/TheMoonsOfNeptune Triton]] was found just seventeen days later.

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!!Neptune and its moons have been visited by:

* ''Voyager 2'' (UsefulNotes/{{NASA}}, flyby, launched 1977, reached Neptune 1989)

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* Discovered: 1846 by Johan Galle, Urbain Le Verrier, & John Couch Adams

Discoveries from the 1990s onward have shown just how profound an effect that Neptune has had on UsefulNotes/{{the Solar System}}'s structure. The inner boundary of the Kuiper Belt is defined by Neptune's gravity, and the scattered disk exists almost entirely because of Kuiper Belt objects that passed too close to the planet and were launched into eccentric orbits. In this way, Neptune is the most similar to Jupiter of any other planet.

The surface gravity on Neptune is 1.14 g, which is 14% stronger than Earth. If you could stand on Neptune, it would be the equivalent of carrying around a heavy backpack on Earth.

[[caption-width-right:769: True color image of the planet Neptune as taken by Voyager 2 during its flyby of the planet in 1989. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy. In reality, it is roughly the same color as Uranus.[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune as taken by Voyager 2 during its flyby of the planet in 1989. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy. In reality, it is roughly the same color as [[UsefulNotes/Uranus Uranus]].[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune as taken by Voyager 2 during its flyby of the planet in 1989. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy. In reality, it is roughly the same color as [[UsefulNotes/Uranus]].[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune as taken by Voyager 2 during its flyby of the planet in 1989. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy. In reality, it is roughly the same color as UsefulNotes/Uranus.[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune as taken by Voyager 2 during its flyby of the planet in 1989. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy.[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune. [[note]] The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy.[[/note]]]]

[[caption-width-right:769: True color image of the planet Neptune. The depiction of it as a dark blue sphere is actually a case of ArtisticLicenceAstronomy.]]

[[quoteright:265:https://static.tvtropes.org/pmwiki/pub/images/neptun_2819.jpg]]
[[caption-width-right:265:The Mystic.]]

Neptune completed its first full orbital period from its discovery in September 2010. From 1930 to 1979, and again from 1999 to 2006, Neptune was not the farthest planet from the Sun as UsefulNotes/{{Pluto}} was considered a planet by astronomers during that period. (From 1979 to 1999, Pluto's highly elliptical orbit brought it closer to the Sun than Neptune, marking the only time that Pluto was ever or will ever be the eighth planet from the Sun -- a very literal moment in the sun -- and likewise the only time that Neptune was ever or will ever be the ''ninth'' planet from the Sun.) Neptune will next reach perihelion in 2042.

Neptune completed its first full orbital period from its discovery in September 2010. From 1930 to 1979, and again from 1999 to 2006, Neptune was not the farthest planet from the Sun as UsefulNotes/{{Pluto}} was considered a planet by astronomers during that period. (From 1979 to 1999, Pluto's highly elliptical orbit brought it closer to the Sun than Neptune, marking the only time that Pluto was ever or will ever be the eighth planet from the Sun -- a very literal moment in the sun -- and likewise the only time that Neptune was ever or will ever be the ''ninth'' planet from the Sun).[[note]]From 1846 to 1851, Neptune was considered the ''twelfth'' planet from the Sun as Ceres, Pallas, Juno, and Vesta were still considered planets before being demoted to asteroids.[[/note]] Neptune will next reach perihelion in 2042.

Neptune completed its first full orbital period from its discovery in September 2010. From 1930 to 1979, and again from 1999 to 2006, Neptune was not the farthest planet from the Sun as UsefulNotes/{{Pluto}} was considered a planet by astronomers during that period. (From 1979 to 1999, Pluto's highly elliptical orbit brought it closer to the Sun than Neptune, marking the only time that Pluto was ever or will ever be the eighth planet from the Sun -- a very literal moment in the sun -- and likewise the only time that Neptune was ever or will ever be the ''ninth'' planet from the Sun.[[note]]From 1846 to 1851, Neptune was considered the ''twelfth'' planet from the Sun as Ceres, Pallas, Juno, and Vesta were still considered planets before being demoted to asteroids.[[/note]] Neptune will next reach perihelion in 2042.

Neptune completed its first full orbital period from its discovery in September 2010. From 1930 to 1979, and again from 1999 to 2006, Neptune was not the farthest planet from the Sun as UsefulNotes/{{Pluto}} was considered a planet by astronomers during that period. (From 1979 to 1999, Pluto's highly elliptical orbit brought it closer to the Sun than Neptune, marking the only time that Pluto was ever or will ever be the eighth planet from the Sun -- a very literal moment in the sun -- and likewise the only time that Neptune was ever or will ever be the ''ninth'' planet from the Sun.)

Neptune completed its first full orbital period from its discovery in September 2010.

A little known fact about Neptune is that, for the first five or so years after it was discovered, it was considered the Solar System's twelfth planet. The demotion of the four largest asteroids[[note]]The largest of these, Ceres, was promoted to dwarf planet after the category was created for Pluto.[[/note]] five years after Neptune's discovery bumped it up to the eighth.