Neptune is the eighth and last planet from the Sun in the Solar System. It is an ice giant. It is the fourth largest planet in the system. Neptune has five rings. These rings are hard to see from the Earth.
|Discovery date||23 September 1846|
|Latin Neptunus, via French Neptune|
Neptune has 17 times more mass than Earth, and has a little bit more mass than Uranus. Neptune is denser and physically smaller than Uranus. Its greater mass causes more gravitational compression of its atmosphere.
Neptune's atmosphere is mostly made up of hydrogen and helium. It also contains small amounts of methane which makes the planet appear blue. Neptune's blue color is much darker than the color of Uranus. Neptune also has the strongest winds of any planet in the Solar System, as high as 2,100 km/h or 1,300 mph.
Astronomers Urbain Le Verrier and John Couch Adams discovered Neptune. It was the first planet to be discovered by mathematical calculations instead of a telescope. In 1821, it was found that Uranus' orbit had some differences from its expected orbit, which meant another planet was nearby. The reason for this was discovered to be Neptune.
The planet has been visited by only one spacecraft, Voyager 2 on 25 August 1989. Neptune once had a huge storm known as the "Great Dark Spot". The storm was discovered in 1989 by Voyager 2. The dark spot was not seen in 1994, and new spots were found since then. It is not known why the dark spot disappeared. Visits by other space probes have been planned.
Galileo Galilei was the first person who saw Neptune. He saw it on 28 December 1612 and 27 January 1613. His drawings showed points near Jupiter where Neptune is placed. But Galileo was not credited for the discovery. He thought Neptune was a "fixed star" instead of a planet. Because Neptune slowly moved across the sky, Galileo's small telescope was not strong enough to see that Neptune was a planet.
In 1821, Alexis Bouvard published the astronomical tables of the orbit of Uranus. Later observations showed that Uranus was moving in an irregular way in its orbit. Some astronomers thought this was caused by another large body. In 1843, John Couch Adams calculated the orbit of an eighth planet that could possibly affect the orbit of Uranus. He sent his calculations to Sir George Airy, the Astronomer Royal. George Airy asked Adams for an explanation. In 1846, Urbain Le Verrier made his own calculations but also failed to get much attention from French astronomers. In the same year, John Herschel began to support the mathematical method and encouraged James Challis to search for the planet. Challis began his search in July 1846. Meanwhile, Le Verrier had convinced Johann Gottfried Galle to search for the planet.
Heinrich d'Arrest, a student at the Berlin Observatory, suggested that a newly drawn map of the sky in the region of Le Verrier's predicted area could be compared with the current sky. This map was needed to look for the change of position of a planet, compared to a fixed star. Neptune was discovered the same night on 23 September 1846. It was found 1° from where Le Verrier had thought it would be. It was about 10° from Adams' prediction. Challis later found out that he had seen the planet twice in August. He did not recognize it at the time because of his careless work approach. Neptune became the first planet to be discovered by mathematical calculations instead of a telescope.
Crediting and namingEdit
When Neptune was discovered, there was also a lot of arguing between the French and the British. They could not agree who was going to receive credit for the discovery. Later, an international agreement decided that both Le Verrier and Adams together deserved credit. However, historians reviewed the topic after the rediscovery in 1998 of the "Neptune papers" (historical documents from the Royal Greenwich Observatory). It had seemingly been stolen and kept by astronomer Olin Eggen for nearly three decades and was only rediscovered (in his ownership) shortly after his death. After reviewing the documents, some historians now think that Adams does not deserve equal credit with Le Verrier.
Shortly after its discovery, Neptune was temporarily called "the planet exterior to Uranus" or "Le Verrier's planet". The first suggestion for a name came from Galle. He proposed the name Janus. In England, Challis suggested the name Oceanus. In France, Arago suggested that the new planet be called Leverrier, a suggestion which was met with a lot of opposition outside France. French almanacs quickly reintroduced the name Herschel for Uranus and Leverrier for the new planet.
Meanwhile, Adams suggested changing the name Georgian to Uranus, while Leverrier (through the Board of Longitude) suggested Neptune for the new planet. Struve gave support of that name on 29 December 1846, to the Saint Petersburg Academy of Sciences. Soon Neptune was internationally agreed among many people. It was the official name for the new planet. In Roman mythology, Neptune was the god of the sea, identified with the Greek god, Poseidon. Neptune's astrological symbol is Neptune's trident.
Mass and compositionEdit
At 102.413×1024kg, Neptune's mass puts the planet between Earth and the largest gas giants. Neptune is the fourth largest planet in the solar system and third heaviest. Neptune is 17 times the mass of Earth, but just 1/18th the mass of Jupiter. Neptune is a little bit more massive than Uranus, even though Neptune is denser and physically smaller than Uranus. Neptune and Uranus are often considered to be part of a sub-class of a gas giant known as "ice giants." It is given their smaller size and big differences in composition compared to Jupiter and Saturn. In the search for extrasolar planets, Neptune has been used as a reference to determine the size and structure of the discovered planet. Some discovered planets that have similar masses like Neptune are often called "Neptunes." 
The atmosphere of Neptune is made up mostly of hydrogen, with a smaller amount of helium. A tiny amount of methane was also detected in the atmosphere. The methane gives Neptune its blue color. The color of Neptune is much darker than the color of Uranus.
Because of Neptune's far distance from the Sun, it gets very little heat. The average temperature on Neptune is about -201°C (−331 °F; 72 K). Therefore, Neptune is the coldest planet in the Solar System. But in the depths of planet the temperature rises slowly. The source of this heating is unknown. Neptune is the farthest planet from the Sun, yet its internal energy is strong enough to create the fastest winds seen in the Solar System, at 1,300 miles per hour (2,100 km/h). Several possible explanations have been suggested. Firstly, radiogenic heating from the planet's core. Among the explanations is the continued radiation into space of leftover heat made by infalling matter during the planet's birth. The last explanation is gravity waves breaking above the tropopause. It has also been suggested that the friction and ram pressure of the diamond hail heats up the planet.
The structure inside Neptune is thought to be similar to the structure inside Uranus. There is likely to be a core, thought to be about 15 Earth masses. It is made up of molten rock and metal surrounded by rock, water, ammonia, and methane. This mixture is referred to as icy. It is called a water-ammonia ocean. More mixtures of methane, ammonia, and water are found in the lower areas of the atmosphere. 
Weather and magnetic fieldEdit
One difference between Neptune and Uranus is the level of its meteorological activity. When the Voyager spacecraft flew by Uranus in 1986, the winds on that planet were observed to be mild. When Voyager flew by Neptune in 1989, powerful weather events were observed. The weather of Neptune has very active storms. Its atmosphere has the highest wind speeds in the Solar System. It may be powered by internal heat flow. Regular winds in the equatorial region have speeds of around 1,200 km/h (750 mph). Winds in storm systems can reach up to 2,100 km/h, near-supersonic speeds.
In 1989, the Great Dark Spot, an anticyclonic storm system, was discovered by NASA's Voyager 2 spacecraft. On 2 November 1994, the Hubble Space Telescope did not see the Great Dark Spot on the planet. Instead, a new storm similar to the Great Dark Spot was found in the planet's northern hemisphere. The reason why the Great Dark Spot has disappeared is unknown. The Scooter is another storm, a white cloud group farther south than the Great Dark Spot. Its nickname was given when first noticed in the months leading up to the Voyager encounter in 1989. It moved faster than the Great Dark Spot. Later images showed clouds that moved even faster than Scooter. The Wizard's Eye/Dark Spot 2 is another southern cyclonic storm, the second strongest storm seen during the 1989 encounter. It originally was completely dark, but as Voyager came closer to the planet, a bright core developed.
Neptune also has similarities with Uranus in its magnetosphere. However, Uranus' magnetosphere is weaker than Neptune's magnetosphere. The magnetic field is strongly tilted compared to its rotational axis at 47°. It is offset at least 0.55 radii (about 13,500 kilometres, bigger than the Earth's diameter, for scale) from the planet's physical center. The unusual course may be caused by flows in the interior of the planet.
Five tiny blue-colored rings have been discovered around the planet. They are not as well known as the rings of Saturn. The rings were discovered by a team led by Edward Guinan. At first, they thought that the rings might not be complete. This was proven wrong by Voyager 2. The planetary rings of Neptune have a weird "clumpy" arrangement. Scientists think that it may be because of the gravitational contact with small moons that orbit near them.
Information was found in the mid-1980s that suggested that the rings were not completely formed. Stellar occultations were found that rarely showed an extra "blink" just before or after the planet moved in front of the star. Pictures from Voyager 2 in 1989 answered the problem. The pictures showed that the ring system had several faint rings. The farthest ring, Adams, has three arcs now named Liberté, Egalité, and Fraternité (Liberty, Equality, and Fraternity).
The existence of arcs is hard to understand. This is because the laws of motion predict that arcs spread out into one ring in a very short time. These arcs may have been created by the gravity of Galatea. It is a moon just inside the ring.
In 2005, observations of the planet from Earth appeared to show that Neptune's rings are more unstable than scientists had believed them to be. The Liberté ring may disappear in less than 100 years.
The largest moon of Neptune is Triton. Triton was discovered on October 10, 1846 by British astronomer William Lassell. Unlike all other large planetary moons, Triton orbits in the other direction to the other moons. This shows the moon was probably captured and maybe was once a Kuiper belt object. It is close enough to Neptune to be locked into a synchronous orbit. It is also slowly moving into Neptune and may one day be torn apart when it passes the Roche limit. Triton is the coldest object that has been measured in the Solar System, with temperatures of −235 °C (38 K, −392 °F).
Neptune's second known moon (by order of distance), the odd moon Nereid, has one of the most unusual orbits of any satellite in the Solar System. Nereid is so far from Neptune that it requires 360 Earth days to make one orbit. It causes the largest elliptical orbit and the largest deviation from a circular path. It is also considered that Nereid may be a captured asteroid or Kuiper Belt object.
From July to September 1989, Voyager 2 discovered six new moons of Neptune. Of these, Proteus is the second most massive Neptunian moon. It has only one quarter of 1% of the mass of Triton. Neptune's closest four moons, Naiad, Thalassa, Despina, and Galatea, orbit close enough to be inside Neptune's rings. The next farthest out, Larissa was originally discovered in 1981 when it had covered up a star. The moon was credited for causing Neptune's ring arcs when Voyager 2 observed Neptune in 1989. Five new unusual moons discovered between 2002 and 2003 were announced in 2004. The latest moon, Hippocamp, was discovered from examining Hubble Telescope images on 16 July 2013.
Neptune can not be seen by just looking at the sky with the naked eye. To see it, a telescope or binoculars is needed. This is because Neptune has a normal brightness between magnitudes +7.7 and +8.0. It can be out-shined by Jupiter's Galilean moons, the dwarf planet Ceres, and the asteroids 4 Vesta, 2 Pallas, 7 Iris, 3 Juno and 6 Hebe. A telescope or strong binoculars will show Neptune as a small blue dot that looks similar to Uranus. The blue color comes from the methane in its atmosphere. Its small size in the night sky has made it difficult to study visually. Most telescopic data was quite limited until the arrival of the Hubble Space Telescope and large ground-based telescopes with adaptive optics.
The average distance between Neptune and the Sun is about 4.5 billion km. Therefore Neptune completes its orbit in every 164 years. On 12 July 2011, Neptune completed its first orbit since its discovery in 1846.
One of Voyager 2's important discoveries was its very close fly-by of Triton, where it took pictures of several parts of the moon. The probe also discovered the Great Dark Spot. However, it had now disappeared after the Hubble Space Telescope took pictures of Neptune in 1994. Originally thought to be a large cloud or cyclonic storm system. It was later guessed to be a hole in the visible cloud deck.
- Interstellar Express — A pair of probes by CNSA that would explore the heliosphere. The second would fly by Neptune in 2038 at a distance of 1,000 km.
- ODINUS — A mission idea based on a twin spacecraft mission to investigate the Neptunian and Uranian systems. Launch date would be 2034.
- OSS mission — A proposed joint flyby mission by ESA and NASA. Its main focus would be to map the gravitational fields in deep space, including the Outer Solar System (up to 50 AU).
- Triton Hopper — A NIAC study of a mission to Neptune with the goal of landing, and flying from site to site, on Neptune's moon Triton.
- Trident — A finalist in the Discovery program, would perform a single flyby of Neptune in 2038 and closely study its largest moon Triton.
- Neptune Odyssey — an idea for a mission by NASA to observe Neptune's atmosphere and the weather on Neptune, as well as its moon Triton. It would launch in 2033 and arrive at Neptune in 2049.
- Hamilton, Calvin J. (4 August 2001). "Neptune". Views of the Solar System. Retrieved 13 August 2007.
- Walter, Elizabeth (21 April 2003). Cambridge Advanced Learner's Dictionary (2nd ed.). Cambridge University Press. ISBN 978-0-521-53106-1.
- "Neptunian". Oxford English Dictionary. Oxford University Press. 2nd ed. 1989.
- "Enabling Exploration with Small Radioisotope Power Systems" (PDF). NASA. September 2004. Archived from the original (PDF) on 22 December 2016. Retrieved 26 January 2016.
- Seligman, Courtney. "Rotation Period and Day Length". Archived from the original on 11 August 2011. Retrieved 13 August 2009.
- Williams, David R. (1 September 2004). "Neptune Fact Sheet". NASA. Archived from the original on 1 July 2010. Retrieved 14 August 2007.
- Souami, D.; Souchay, J. (July 2012). "The solar system's invariable plane". Astronomy & Astrophysics. 543: 11. Bibcode:2012A&A...543A.133S. doi:10.1051/0004-6361/201219011. A133.
- "HORIZONS Web-Interface". ssd.jpl.nasa.gov.
- de Pater, Imke; Lissauer, Jack J. (2015). Planetary Sciences (2nd updated ed.). New York: Cambridge University Press. p. 250. ISBN 978-0-521-85371-2. Archived from the original on 26 November 2016. Retrieved 17 August 2016.
- Espenak, Fred (20 July 2005). "Twelve Year Planetary Ephemeris: 1995–2006". NASA. Archived from the original on 5 December 2012. Retrieved 1 March 2008.
- Hirschfeld, Alan (2001). Parallax:The Race to Measure the Cosmos. New York, New York: Henry Holt. ISBN 0-8050-7133-4.
- Littmann, Mark; Standish, E.M. (2004). Planets Beyond: Discovering the Outer Solar System. Courier Dover Publications. ISBN 978-0-486-43602-9.
- A. Bouvard (1821), Tables astronomiques publiées par le Bureau des Longitudes de France. Paris: Bachelier
- "Neptune: The first planet discovered by mathematical rather than observational means: discovered simultaneously by Le Verrier and Adams : History of Information". Jeremy Norman's History of Information. Retrieved 2021-06-14.
- [Anon.] (2001) "Bouvard, Alexis", Encyclopædia Britannica, Deluxe CDROM edition
- "John Couch Adams' account of the discovery of Neptune". Maths History. Retrieved 10 May 2021.
- Airy, G. B. (1 January 1970). "Account of some circumstances historically connected with the discovery of the planet exterior to Uranus". Astronomische Nachrichten No. 585. 25 (10): 131–148. doi:10.1002/asna.18470251002.
- Mars, Kelli (2021-09-22). "175 Years Ago: Astronomers Discover Neptune, the Eighth Planet". NASA. Retrieved 2022-03-22.
- "In Depth | Neptune". NASA Solar System Exploration. Retrieved 2021-06-14.
- Kollerstrom, Nick (2001). "Neptune's Discovery. The British Case for Co-Prediction". University College London. Archived from the original on 2005-11-16.
- William Sheehan, Nicholas Kollerstrom, Craig B. Waff (December 2004). The Case of the Pilfered Planet - Did the British steal Neptune? Scientific American.
- Moore, Patrick (2000). The Data Book of Astronomy. pp. 206.
- Hind, J. R. (1847). "Second report of proceedings in the Cambridge Observatory relating to the new Planet (Neptune)". Astronomische Nachrichten. 25 (21): 309–314. Bibcode:1847AN.....25..309.. doi:10.1002/asna.18470252102. Smithsonian/NASA Astrophysics Data System (ADS).
- "Enabling Exploration with Small Radioisotope Power Systems" (PDF). 22 December 2016. Archived (PDF) from the original on 2016-12-22. Retrieved 10 May 2021.
- "Neptune". nineplanets.org. Retrieved 5 November 2010.
- "StarChild Question of the Month for August 2002". NASA. August 2002. Retrieved 5 November 2010.
- "Solar System Exploration: Multimedia: Gallery". National Aeronautics and Space Administration (NASA). 2010-03-17. Archived from the original on 2010-03-17. Retrieved 2021-06-23.
- "Neptune Fact Sheet". nssdc.gsfc.nasa.gov. Retrieved 2021-06-14.
- Bradford A. Smith, «Neptune », World Book Online Reference Center, 2004, p. 5
- Helled, Ravit; Nettelmann, Nadine; Guillot, Tristan (2020-03-25). "Uranus and Neptune: Origin, Evolution and Internal Structure". Space Science Reviews. 216 (3): 38. arXiv:1909.04891. Bibcode:2020SSRv..216...38H. doi:10.1007/s11214-020-00660-3. ISSN 1572-9672. S2CID 202558606.
- "Trio of Neptunes". Astrobiology Magazine. 21 May 2006. Retrieved 9 June 2021.
- "All About Neptune | NASA Space Place – NASA Science for Kids". spaceplace.nasa.gov. Retrieved 2021-06-12.
- "Neptune". NASA. Archived from the original on 13 December 2006. Retrieved 11 November 2010.
- "Neptune". NASA. Archived from the original on 13 December 2006. Retrieved 11 November 2010.
- "Solar System Temperatures". NASA Solar System Exploration. Retrieved 2021-06-12.
- Elkins-Tanton, Linda T. (2006). Uranus, Neptune, Pluto, and the Outer Solar System. Infobase Publishing. p. 75. ISBN 978-1-4381-0729-5.
- Suomi, V. E.; Limaye, S. S.; Johnson, D. R. (1991). "High winds of Neptune - A possible mechanism". Science. 251 (4996): 929–932. Bibcode:1991Sci...251..929S. doi:10.1126/science.251.4996.929. PMID 17847386. S2CID 46419483.
- Cain, Fraser (2008-12-09). "What is the Weather Like on Neptune?". Universe Today. Retrieved 2021-06-12.
- McHugh, J. P., Computation of Gravity Waves near the Tropopause Archived 27 October 2007 at the Wayback Machine, AAS/Division for Planetary Sciences Meeting Abstracts, p. 53.07, September 1999
- McHugh, J. P., and Friedson, A. J., Neptune's Energy Crisis: Gravity Wave Heating of the Stratosphere of Neptune, Bulletin of the American Astronomical Society, p.1078, September 1996
- Hubbard, W.B. 1997. Neptune's deep chemistry. Science. 275 (5304): 1279–80.
- Atreya, S.; Egeler, P.; Baines, K. (2006). "Water-ammonia ionic ocean on Uranus and Neptune?" (PDF). Geophysical Research Abstracts. 8. 05179.
- Kerr, Richard A. 1999. Neptune may crush methane into diamonds". Science. 286 (5437): 25a–25.
- Kaplan, Sarah (2017). "It rains solid diamonds on Uranus and Neptune". The Washington Post. ISSN 0190-8286. Retrieved 2021-06-12.
- The Sun, Planets, and Dwarf Planets. PediaPress.
- Hammel, H.B.; et al. (1989). "Neptune's wind speeds obtained by tracking clouds in Voyager images". Science. 245 (4924): 1367–1369. Bibcode:1989Sci...245.1367H. doi:10.1126/science.245.4924.1367. PMID 17798743. S2CID 206573894.
- "Hubble captures birth of giant storm on Neptune". ScienceDaily. Retrieved 2021-06-12.
- "What is the Great Dark Spot?". Cool Cosmos. Retrieved 2021-06-12.
- Hammel, H.B.; Lockwood, G. W.; Mills, J. R.; Barnet, C. D. (1995). "Hubble Space Telescope Imaging of Neptune's Cloud Structure in 1994". Science. 268 (5218): 1740–1742. Bibcode:1995Sci...268.1740H. doi:10.1126/science.268.5218.1740. ISSN 0036-8075. PMID 17834994. S2CID 11688794.
- Sromovsky L.A.; Fry P.M.; Dowling T.E. & Baines K.H. 2000. The unusual dynamics of new dark spots on Neptune. Bulletin of the American Astronomical Society. 32: 1005
- "Neptune Scooter". The Planetary Society. Retrieved 2021-06-15.
- "Planet Neptune | Introduction to Astronomy". courses.lumenlearning.com. Retrieved 2021-06-15.
- "Catalog Page for PIA00064". Jet Propulsion Laboratory California Institute of Technology. Retrieved 10 May 2021.
- Stanley, Sabine; Bloxham, Jeremy (11 March 2004). "Convective-region geometry as the cause of Uranus' and Neptune's unusual magnetic fields". Nature. 428 (6979): 151–153. Bibcode:2004Natur.428..151S. doi:10.1038/nature02376. PMID 15014493. S2CID 33352017.
- Schörghofer, Norbert; Hsieh, Henry H. (2018). "Ice Loss From the Interior of Small Airless Bodies According to an Idealized Model". Journal of Geophysical Research: Planets. 123 (9): 2322–2335. arXiv:1802.01293. Bibcode:2018JGRE..123.2322S. doi:10.1029/2018je005568. ISSN 2169-9097. S2CID 119100900.
- Cox, Arthur N. (2001). Allen's Astrophysical Quantities. Springer. ISBN 978-0-387-98746-0.
- "In Depth | Neptune". NASA Solar System Exploration. Retrieved 10 May 2021.
- "Neptune's rings are fading away". New Scientist. 26 March 2005. Retrieved 9 June 2021.
- "Nasa's Hubble telescope discovers new Neptune moon". BBC. 15 July 2013. Retrieved 16 July 2013.
- "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. U.S. Geological Survey.
- "In Depth | Triton". NASA Solar System Exploration. Retrieved 2021-06-13.
- Agnor, Craig B.; Hamilton, Douglas P. 2006. Neptune's capture of its moon Triton in a binary–planet gravitational encounter. Nature 441 (7090): 192–194.
- Jankowski, David G.; Chyba, Christopher F.; Nicholson, Philip D. (1989). "Tidal evolution in the Neptune-Triton system". Astronomy and Astrophysics. 219 (1–2): L23–L26. Bibcode:1989A&A...219L..23C.
- Nelson R.M; Smythe W.D; Wallis B.D; Horn L.J; et al 1990. Temperature and thermal emissivity of the surface of Neptune's satellite Triton. Science. 250 (4979): 429–31.
- "In Depth | Nereid". NASA Solar System Exploration. Retrieved 2021-06-11.
- Stone, E.C.; Miner, E.D. (1989). "The Voyager 2 Encounter with the Neptunian System". Science. 246 (4936): 1417–21.
- "Planet Neptune's moons". The New Times | Rwanda. 2010-05-29. Retrieved 2021-06-15.
- "In Depth | Larissa". NASA Solar System Exploration. Retrieved 2021-06-15.
- Holman, Matthew J. (19 August 2004). "Discovery of five irregular moons of Neptune". Nature. 430 (7002): 865–867. Bibcode:2004Natur.430..865H. doi:10.1038/nature02832. PMID 15318214. S2CID 4412380.
- "Five new moons for planet Neptune". BBC News. 18 August 2004. Retrieved 6 August 2007.
- "Nasa's Hubble telescope discovers new Neptune moon". BBC News. 2013-07-15. Retrieved 2021-06-13.
- Mallama, A.; Hilton, J.L. (2018). "Computing Apparent Planetary Magnitudes for The Astronomical Almanac". Astronomy and Computing. 25: 10–24. arXiv:1808.01973. Bibcode:2018A&C....25...10M. doi:10.1016/j.ascom.2018.08.002. S2CID 69912809.
- See the respective articles for magnitude data.
- Moore, Patrick (2000). The Data Book of Astronomy. pp. 207. ISBN 9780750306201.
- "APOD: 2000 February 18 - Neptune through Adaptive Optics". apod.nasa.gov. Retrieved 10 May 2021.
- "In Depth | Neptune". NASA Solar System Exploration. Retrieved 2021-09-13.
- Gaherty, Geoff (12 July 2011). "Neptune Completes First Orbit Since Its Discovery in 1846". Space.com. Retrieved 10 May 2021.
- Chang, Kenneth (18 August 2014). "Dark Spots in Our Knowledge of Neptune". The New York Times. ISSN 0362-4331. Retrieved 15 May 2021.
- "Exploration | Neptune". NASA Solar System Exploration. Retrieved 15 May 2021.
- Greicius, Tony (2015-02-17). "Voyager Map Details Neptune's Strange Moon Triton". NASA. Retrieved 2021-06-11.
- Steigerwald, Bill (2019-03-14). "Hubble Tracks the Lifecycle of Giant Storms on Neptune". NASA. Retrieved 2021-06-11.
- "Neptune's Great Dark Spot of 1989" Windows to the Universe
- Phillips, Cynthia (3 November 2007). "Fascination with Distant Worlds". Archived from the original on 2007-11-03. Retrieved 10 May 2021.
- Jones, Andrew (November 19, 2019). China Considers Voyager-like Mission to Interstellar Space . Retrieved 28 August, 2021
- "Origins, Dynamics and Interiors of Neptunian and Uranian Systems". Retrieved 5 August 2015.
- "Astronomers Make the Case for a Mission to Neptune and Uranus". The Physics arXiv Blog. arXiv. 17 February 2014. Retrieved 5 August 2015.
- Christophe; et al. (October 2012). "OSS (Outer Solar System): a fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt". Experimental Astronomy. 34 (2): 203–42. arXiv:1106.0132. Bibcode:2012ExA....34..203C. doi:10.1007/s10686-012-9309-y. S2CID 55295857.
- Steven Oleson (7 May 2015). "Triton Hopper: Exploring Neptune's Captured Kuiper Belt Object". NASA Glenn Research Center. Retrieved 11 February 2017.
- "Neptune's Moon Triton Is Destination of Proposed NASA Mission". New York Times. 2019-03-19. Retrieved 27 March 2019.
- Abigail Rymer; Brenda Clyde; Kirby Runyon (August 2020). "Neptune Odyssey: Mission to the Neptune-Triton System" (PDF). Retrieved 18 April 2021.
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