fbpx
Wikipedia

Neptune

October 03, 2023

This article is about the planet. For the Roman god, see Neptune (mythology). For other uses, see Neptune (disambiguation).
"Eighth planet" redirects here. For other systems of numbering planets, see Planet § History.

Neptune is the eighth planet from the Sun and the farthest IAU-recognized planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, and slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. Being composed primarily of gases and liquids, it has no well-defined solid surface. The planet orbits the Sun once every 164.8 years at an average distance of 30.1 astronomical units (4.5 billion kilometres; 2.8 billion miles). It is named after the Roman god of the sea and has the astronomical symbol , representing Neptune's trident.[d]

Neptune
Photograph taken by NASA's Voyager 2 in 1989
Discovery[1]
Discovered by
Discovery date23 September 1846
Designations
Pronunciation/ˈnɛptjuːn/ ⓘ[2]
Named after
Latin Neptunus, via French Neptune
AdjectivesNeptunian (/nɛpˈtjuːniən/),[3] Poseidean[4]
Symbol, historically also
Orbital characteristics[5][a]
Epoch J2000
Aphelion30.33 AU (4.54 billion km)
Perihelion29.81 AU (4.46 billion km)
30.07 AU (4.50 billion km)
Eccentricity0.008678
367.49 days[7]
5.43 km/s[7]
259.883°
Inclination1.770° to ecliptic
6.43° to Sun's equator
0.74° to invariable plane[8]
131.783°
2042-Sep-04[9]
273.187°
Known satellites14
Physical characteristics
Mean radius
24,622±19 km[10][b]
Equatorial radius
24,764±15 km[10][b]
3.883 Earths
Polar radius
24,341±30 km[10][b]
3.829 Earths
Flattening0.0171±0.0013
7.6187×109 km2[11][b]
14.98 Earths
Volume6.253×1013 km3[7][b]
57.74 Earths
Mass1.02413×1026 kg[7]
17.147 Earths
5.15×10−5 Suns
Mean density
1.638 g/cm3[7][c]
11.15 m/s2[7][b]
1.14 g
0.23[12] (estimate)
23.5 km/s[7][b]
0.67125 d
16 h 6 m 36 s[6]
0.6713 day[7]
16 h 6 min 36 s
Equatorial rotation velocity
2.68 km/s (9,650 km/h)
28.32° (to orbit)[7]
North pole right ascension
19h 57m 20s[10]
299.3°
North pole declination
42.950°[10]
Albedo0.290 (bond)[13]
0.442 (geom.)[14]
Surface temp. min mean max
1 bar level 72 K (−201 °C)[7]
0.1 bar (10 kPa) 55 K (−218 °C)[7]
7.67[15] to 8.00[15]
−6.9[16]
2.2–2.4″[7][17]
Atmosphere[7]
19.7±0.6 km
Composition by volume
  • 80%±3.2% hydrogen
  • 19%±3.2% helium
  • 1.5%±0.5% methane
  • ~0.019% hydrogen deuteride
  • ~0.00015% ethane
  • Icy volatiles:

Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical predictions rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to hypothesise that its orbit was subject to gravitational perturbation by an unknown planet. After Bouvard's death, the position of Neptune was predicted from his observations, independently, by John Couch Adams and Urbain Le Verrier. Neptune was subsequently observed with a telescope on 23 September 1846[1] by Johann Galle within a degree of the position predicted by Le Verrier. Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining 14 known 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. Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989; Voyager 2 remains the only spacecraft to have visited Neptune.[18][19] 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 the gas giants (Jupiter and Saturn), Neptune's atmosphere is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen, but contains a higher proportion of ices such as water, ammonia and methane. Similar to Uranus, its interior is primarily composed of ices and rock;[20] both planets are normally considered "ice giants" to distinguish them.[21] Along with Rayleigh scattering, traces of methane in the outermost regions in part account for the planet's blue appearance.[22] Newest data from the Gemini observatory shows the blue colour is more saturated than the one present on Uranus due to the thinner haze of Neptune's more active atmosphere.[23][24][25]

In contrast to the hazy, relatively featureless atmosphere of Uranus, Neptune's atmosphere has active and visible weather patterns. 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. More recently, in 2018, a newer main dark spot and smaller dark spot were identified and studied.[26] In addition, these weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 km/h (580 m/s; 1,300 mph).[27] Because of its great distance from the Sun, Neptune'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 centre are approximately 5,400 K (5,100 °C; 9,300 °F).[28][29] Neptune has a faint and fragmented ring system (labelled "arcs"), which was discovered in 1984, then later confirmed by Voyager 2.[30]

History

Discovery

Main article: Discovery of Neptune
 
Galileo Galilei

Some of the earliest recorded observations ever made through a telescope, Galileo Galilei's drawings on 28 December 1612 and 27 January 1613 contain plotted points that match with what is now known to have been the positions of Neptune on those dates. On both occasions, Galileo seems to have mistaken Neptune for a fixed star when it appeared close—in conjunction—to Jupiter in the night sky.[31] Hence, he is not credited with Neptune's discovery. At his first observation in December 1612, Neptune was almost stationary in the sky because it had just turned retrograde that day. This apparent backward motion is created when Earth's orbit takes it past an outer planet. Because Neptune was only beginning its yearly retrograde cycle, the motion of the planet was far too slight to be detected with Galileo's small telescope.[32] In 2009, a study suggested that Galileo was at least aware that the "star" he had observed had moved relative to fixed stars.[33]

In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbour Uranus.[34] Subsequent observations revealed substantial deviations from the tables, leading Bouvard to hypothesise that an unknown body was perturbing the orbit through gravitational interaction.[35] In 1843, John Couch Adams began work on the orbit of Uranus using the data he had. He requested extra data from Sir George Airy, the Astronomer Royal, who supplied it in February 1844. Adams continued to work in 1845–1846 and produced several different estimates of a new planet.[36][37]

 
Urbain Le Verrier

In 1845–1846, Urbain Le Verrier, independently of Adams, developed his own calculations but aroused no enthusiasm in his compatriots. 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. Challis vainly scoured the sky throughout August and September.[35][38] Challis had, in fact, observed Neptune a year before the planet's subsequent discoverer, Johann Gottfried Galle, and on two occasions, 4 and 12 August 1845. However, his out-of-date star maps and poor observing techniques meant that he failed to recognise the observations as such until he carried out later analysis. Challis was full of remorse but blamed his neglect on his maps and the fact that he was distracted by his concurrent work on comet observations.[39][35][40]

Meanwhile, Le Verrier sent a letter and urged Berlin Observatory astronomer Galle to search with the observatory's refractor. 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. On the evening of 23 September 1846, the day Galle received the letter, he discovered Neptune just northeast of Iota Aquarii, 1° from the "five degrees east of Delta Capricorn" position Le Verrier had predicted it to be,[41][42] about 12° from Adams's prediction, and on the border of Aquarius and Capricornus according to the modern IAU constellation boundaries.

In the wake of the discovery, there was a heated nationalistic rivalry between the French and the British over who deserved credit for the discovery. Eventually, an international consensus emerged that Le Verrier and Adams deserved joint credit. Since 1966, Dennis Rawlins has questioned the credibility of Adams's claim to co-discovery, and the issue was re-evaluated by historians with the return in 1998 of the "Neptune papers" (historical documents) to the Royal Observatory, Greenwich.[43][44]

Naming

Shortly after its discovery, Neptune was referred to simply as "the planet exterior to Uranus" or as "Le Verrier's planet". The first suggestion for a name came from Galle, who proposed the name Janus. In England, Challis put forward the name Oceanus.[45]

Claiming the right to name his discovery, Le Verrier quickly proposed the name Neptune for this new planet, though falsely stating that this had been officially approved by the French Bureau des Longitudes.[46] In October, he sought to name the planet Le Verrier, after himself, and he had loyal support in this from the observatory director, François Arago. This suggestion met with stiff resistance outside France.[47] French almanacs quickly reintroduced the name Herschel for Uranus, after that planet's discoverer Sir William Herschel, and Leverrier for the new planet.[48]

Struve came out in favour of the name Neptune on 29 December 1846, to the Saint Petersburg Academy of Sciences.[49] Soon, Neptune became the internationally accepted name. In Roman mythology, Neptune was the god of the sea, identified with the Greek Poseidon. The demand for a mythological name seemed to be in keeping with the nomenclature of the other planets, all of which were named for deities in Greek and Roman mythology.[e][50]

Most languages today use some variant of the name "Neptune" for the planet; indeed, in Chinese, Vietnamese, Japanese, and Korean, the planet's name was translated as "sea king star" (海王星).[51][52] In Mongolian, Neptune is called Dalain van (Далайн ван), reflecting its namesake god's role as the ruler of the sea. In modern Greek the planet is called Poseidon (Ποσειδώνας, Poseidonas), the Greek counterpart of Neptune.[53] In Hebrew, Rahab (רהב), from a Biblical sea monster mentioned in the Book of Psalms, was selected in a vote managed by the Academy of the Hebrew Language in 2009 as the official name for the planet, even though the existing Latin term Neptun (נפטון) is commonly used.[54][55] In Māori, the planet is called Tangaroa, named after the Māori god of the sea.[56] In Nahuatl, the planet is called Tlāloccītlalli, named after the rain god Tlāloc.[56] In Thai, Neptune is referred to by its Westernised name Dao Nepchun/Nepjun (ดาวเนปจูน), but is also called Dao Ket (ดาวเกตุ, lit. 'star of Ketu'), after Ketu (केतु), the descending lunar node, who plays a role in Hindu astrology. In Malay, the name Waruna, after the Hindu god of seas, is attested as far back as the 1970s,[57] but was eventually superseded by the Latinate equivalents Neptun (in Malaysian[58]) or Neptunus (in Indonesian[59]).

The usual adjectival form is Neptunian. The nonce form Poseidean (/pəˈsaɪdiən/), from Poseidon, has also been used,[4] though the usual adjectival form of Poseidon is Poseidonian (/ˌpɒsaɪˈdoʊniən/).[60]

Status

From its discovery in 1846 until the discovery of Pluto in 1930, Neptune was the farthest known planet. When Pluto was discovered, it was considered a planet, and Neptune thus became the second-farthest known planet, except for a 20-year period between 1979 and 1999 when Pluto's elliptical orbit brought it closer than Neptune to the Sun, making Neptune the ninth planet from the Sun during this period.[61][62] The increasingly accurate estimations of Pluto's mass from ten times that of Earth's to far less than that of the Moon[63] and the discovery of the Kuiper belt in 1992 led many astronomers to debate whether Pluto should be considered a planet or as part of the Kuiper belt.[64][65] In 2006, the International Astronomical Union defined the word "planet" for the first time, reclassifying Pluto as a "dwarf planet" and making Neptune once again the outermost-known planet in the Solar System.[66]

Physical characteristics

 
A size comparison of Neptune and Earth

Neptune's mass of 1.0243×1026 kg[7] is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter.[f] Its gravity at 1 bar is 11.15 m/s2, 1.14 times the surface gravity of Earth,[67] and surpassed only by Jupiter.[68] Neptune's equatorial radius of 24,764 km[10] is nearly four times that of Earth. 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.[69] In the search for exoplanets, Neptune has been used as a metonym: discovered bodies of similar mass are often referred to as "Neptunes",[70] just as scientists refer to various extrasolar bodies as "Jupiters".

Internal structure

See also: Extraterrestrial diamonds

Neptune's internal structure resembles that of Uranus. Its atmosphere forms about 5 to 10% of its mass and extends perhaps 10 to 20% of the way towards the core. Pressure in the atmosphere reaches about 10 GPa, or about 100,000 times that of Earth's atmosphere. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere.[28]

 
Physical and chemical composition of Neptune's interior

The mantle is equivalent to 10 to 15 Earth masses and is rich in water, ammonia and methane.[1] As is customary in planetary science, this mixture is referred to as icy even though it is a hot, dense fluid (supercritical fluid). This fluid, which has a high electrical conductivity, is sometimes called a water–ammonia ocean.[71] The mantle may consist of a layer of ionic water in which the water molecules break down into a soup of hydrogen and oxygen ions, and deeper down superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice.[72] At a depth of 7,000 km, the conditions may be such that methane decomposes into diamond crystals that rain downwards like hailstones.[73][74][75] Scientists also believe that this kind of diamond rain occurs on Jupiter, Saturn, and Uranus.[76][74] Very-high-pressure experiments at the Lawrence Livermore National Laboratory suggest that the top of the mantle may be an ocean of liquid carbon with floating solid 'diamonds'.[77][78][79]

The core of Neptune is likely composed of iron, nickel and silicates, with an interior model giving a mass about 1.2 times that of Earth.[80] The pressure at the centre is 7 Mbar (700 GPa), about twice as high as that at the centre of Earth, and the temperature may be 5,400 K.[28][29]

Atmosphere

 
Combined colour and near-infrared image of Neptune, showing bands of methane in its atmosphere, and four of its moons, Proteus, Larissa, Galatea, and Despina
A time-lapse video of Neptune and its moons

At high altitudes, Neptune's atmosphere is 80% hydrogen and 19% helium.[28] A trace amount of methane is also present. Prominent absorption bands of methane exist at wavelengths above 600 nm, in the red and infrared portion of the spectrum. As with Uranus, this absorption of red light by atmospheric methane is part of what gives Neptune its blue hue,[81] although Neptune's blue differs from Uranus's milder light blue.

 
Neptune - cloud cover over three decades (1994-2023)[82]

Neptune's atmosphere is subdivided into two main regions: the lower troposphere, where temperature decreases with altitude, and the stratosphere, where temperature increases with altitude. The boundary between the two, the tropopause, lies at a pressure of 0.1 bars (10 kPa).[21] The stratosphere then gives way to the thermosphere at a pressure lower than 10−5 to 10−4 bars (1 to 10 Pa).[21] The thermosphere gradually transitions to the exosphere.

 
Bands of high-altitude clouds cast shadows on Neptune's lower cloud deck.

Models suggest that Neptune's troposphere is banded by clouds of varying compositions depending on altitude.[82] The upper-level clouds lie at pressures below one bar, where the temperature is suitable for methane to condense. For pressures between one and five bars (100 and 500 kPa), clouds of ammonia and hydrogen sulfide are thought to form. Above a pressure of five bars, the clouds may consist of ammonia, ammonium sulfide, hydrogen sulfide and water. Deeper clouds of water ice should be found at pressures of about 50 bars (5.0 MPa), where the temperature reaches 273 K (0 °C). Underneath, clouds of ammonia and hydrogen sulfide may be found.[83]

High-altitude clouds on Neptune have been observed casting shadows on the opaque cloud deck below. There are also high-altitude cloud bands that wrap around the planet at constant latitudes. These circumferential bands have widths of 50–150 km and lie about 50–110 km above the cloud deck.[84] These altitudes are in the layer where weather occurs, the troposphere. Weather does not occur in the higher stratosphere or thermosphere. In August 2023, the clouds of Neptune vanished, possibly due to "solar flare".[82] Thirty years of observations by Hubble Space Telescope and ground-based telescopes showed that Neptune's cloud activity is bound to Solar cycles, and not to the planet's seasons.[85][86]

Neptune's spectra suggest that its lower stratosphere is hazy due to condensation of products of ultraviolet photolysis of methane, such as ethane and ethyne.[21][28] The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide.[21][87] The stratosphere of Neptune is warmer than that of Uranus due to the elevated concentration of hydrocarbons.[21]

For reasons that remain obscure, the planet's thermosphere is at an anomalously high temperature of about 750 K.[88][89] The planet is too far from the Sun for this heat to be generated by ultraviolet radiation. One candidate for a heating mechanism is atmospheric interaction with ions in the planet's magnetic field. Other candidates are gravity waves from the interior that dissipate in the atmosphere. The thermosphere contains traces of carbon dioxide and water, which may have been deposited from external sources such as meteorites and dust.[83][87]

Magnetosphere

Neptune resembles Uranus in its magnetosphere, with a magnetic field strongly tilted relative to its rotational axis at 47° and offset at least 0.55 radius, or about 13,500 km from the planet's physical centre. Before Voyager 2's arrival at Neptune, it was hypothesised that Uranus's tilted magnetosphere was the result of its sideways rotation. In comparing the magnetic fields of the two planets, scientists now think the extreme orientation may be characteristic of flows in the planets' interiors. This field may be generated by convective fluid motions in a thin spherical shell of electrically conducting liquids (probably a combination of ammonia, methane and water)[83] resulting in a dynamo action.[90]

The dipole component of the magnetic field at the magnetic equator of Neptune is about 14 microteslas (0.14 G).[91] The dipole magnetic moment of Neptune is about 2.2 × 1017 T·m3 (14 μT·RN3, where RN is the radius of Neptune). Neptune's magnetic field has a complex geometry that includes relatively large contributions from non-dipolar components, including a strong quadrupole moment that may exceed the dipole moment in strength. By contrast, Earth, Jupiter and Saturn have only relatively small quadrupole moments, and their fields are less tilted from the polar axis. The large quadrupole moment of Neptune may be the result of an offset from the planet's centre and geometrical constraints of the field's dynamo generator.[92][93]

Neptune's bow shock, where the magnetosphere begins to slow the solar wind, occurs at a distance of 34.9 times the radius of the planet. The magnetopause, where the pressure of the magnetosphere counterbalances the solar wind, lies at a distance of 23–26.5 times the radius of Neptune. The tail of the magnetosphere extends out to at least 72 times the radius of Neptune, and likely much farther.[92]

Climate

 
The Great Dark Spot (top), Scooter (middle white cloud),[94] and the Small Dark Spot (bottom), with contrast exaggerated.

Neptune's weather is characterised by extremely dynamic storm systems, with winds reaching speeds of almost 600 m/s (2,200 km/h; 1,300 mph)—exceeding supersonic flow.[27] More typically, by tracking the motion of persistent clouds, wind speeds have been shown to vary from 20 m/s in the easterly direction to 325 m/s westward.[95] At the cloud tops, the prevailing winds range in speed from 400 m/s along the equator to 250 m/s at the poles.[83] Most of the winds on Neptune move in a direction opposite the planet's rotation.[96] The general pattern of winds showed prograde rotation at high latitudes vs. retrograde rotation at lower latitudes. The difference in flow direction is thought to be a "skin effect" and not due to any deeper atmospheric processes.[21] At 70° S latitude, a high-speed jet travels at a speed of 300 m/s.[21]

Neptune differs from Uranus in its typical level of meteorological activity. Voyager 2 observed weather phenomena on Neptune during its 1989 flyby,[97] but no comparable phenomena on Uranus during its 1986 fly-by.

The abundance of methane, ethane and acetylene at Neptune's equator is 10–100 times greater than at the poles. This is interpreted as evidence for upwelling at the equator and subsidence near the poles because photochemistry cannot account for the distribution without meridional circulation.[21]

In 2007, it was discovered that the upper troposphere of Neptune's south pole was about 10 K warmer than the rest of its atmosphere, which averages approximately 73 K (−200 °C). The temperature differential is enough to let methane, which elsewhere is frozen in the troposphere, escape into the stratosphere near the pole.[98] The relative "hot spot" is due to Neptune's axial tilt, which has exposed the south pole to the Sun for the last quarter of Neptune's year, or roughly 40 Earth years. As Neptune slowly moves towards the opposite side of the Sun, the south pole will be darkened and the north pole illuminated, causing the methane release to shift to the north pole.[99]

Because of seasonal changes, the cloud bands in the southern hemisphere of Neptune have been observed to increase in size and albedo. This trend was first seen in 1980. The long orbital period of Neptune results in seasons lasting forty years.[100]

Storms

In 1989, the Great Dark Spot, an anticyclonic storm system spanning 13,000 km × 6,600 km (8,100 mi × 4,100 mi)[97] was discovered by NASA's Voyager 2 spacecraft. The storm resembled the Great Red Spot of Jupiter. Some five years later, 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 Neptune's northern hemisphere.[101]

The Scooter is another storm, a white cloud group farther south than the Great Dark Spot. This nickname first arose during the months leading up to the Voyager 2 encounter in 1989, when they were observed moving at speeds faster than the Great Dark Spot (and images acquired later would subsequently reveal the presence of clouds moving even faster than those that had initially been detected by Voyager 2).[96] The Small Dark Spot is a southern cyclonic storm, the second-most-intense storm observed during the 1989 encounter. It was initially completely dark, but as Voyager 2 approached the planet, a bright core developed and can be seen in most of the highest-resolution images.[102] More recently, in 2018, a newer main dark spot and smaller dark spot were identified and studied.[26] In 2023, the first ground-based observation of a dark spot on Neptune was announced.[103]

Neptune's dark spots are thought to occur in the troposphere at lower altitudes than the brighter cloud features,[104] so they appear as holes in the upper cloud decks. As they are stable features that can persist for several months, they are thought to be vortex structures.[84] Often associated with dark spots are brighter, persistent methane clouds that form around the tropopause layer.[105] The persistence of companion clouds shows that some former dark spots may continue to exist as cyclones even though they are no longer visible as a dark feature. Dark spots may dissipate when they migrate too close to the equator or possibly through some other, unknown mechanism.[106]

  •  

    The appearance of a Northern Great Dark Spot in 2018 is evidence of a huge storm brewing.[107]

  •  

    The Northern Great Dark Spot and a smaller companion storm imaged by Hubble in 2020[108]

  •  

    The Great Dark Spot in a color-uncalibrated image by Voyager 2.

  •  

    Neptune's shrinking vortex[109]

Internal heating

 
Four images taken a few hours apart with the NASA/ESA Hubble Space Telescope's Wide Field Camera 3. Near infrared radiation data has been used as red channel.[110]

Neptune's more varied weather when compared to Uranus is due in part to its higher internal heating. The upper regions of Neptune's troposphere reach a low temperature of 51.8 K (−221.3 °C). At a depth where the atmospheric pressure equals 1 bar (100 kPa), the temperature is 72.00 K (−201.15 °C).[111] Deeper inside the layers of gas, the temperature rises steadily. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun;[112] whereas Neptune radiates about 2.61 times as much energy as it receives from the Sun.[113] Neptune is the farthest planet from the Sun, and lies over 50% farther from the Sun than Uranus, and receives only 40% of its amount of sunlight,[21] yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Depending on the thermal properties of its interior, the heat left over from Neptune's formation may be sufficient to explain its current heat flow, though it is more difficult to simultaneously explain Uranus's lack of internal heat while preserving the apparent similarity between the two planets.[114]

Orbit and rotation

 
Neptune (red arc) completes one orbit around the Sun (centre) for every 164.79 orbits of Earth. The light blue object represents Uranus.

The average distance between Neptune and the Sun is 4.5 billion km (about 30.1 astronomical units (AU)), and it completes an orbit on average every 164.79 years, subject to a variability of around ±0.1 years. The perihelion distance is 29.81 AU; the aphelion distance is 30.33 AU.[g]

On 11 July 2011, Neptune completed its first full barycentric orbit since its discovery in 1846,[116] although it did not appear at its exact discovery position in the sky, because Earth was in a different location in its 365.26 day orbit. Because of the motion of the Sun in relation to the barycentre of the Solar System, on 11 July Neptune was also not at its exact discovery position in relation to the Sun; if the more common heliocentric coordinate system is used, the discovery longitude was reached on 12 July 2011.[11][117][118]

The elliptical orbit of Neptune is inclined 1.77° compared to that of Earth.

The axial tilt of Neptune is 28.32°,[119] which is similar to the tilts of Earth (23°) and Mars (25°). As a result, Neptune experiences similar seasonal changes to Earth. The long orbital period of Neptune means that the seasons last for forty Earth years.[100] Its sidereal rotation period (day) is roughly 16.11 hours.[11] Because its axial tilt is comparable to Earth's, the variation in the length of its day over the course of its long year is not any more extreme.

Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates with a period of about 18 hours, which is slower than the 16.1-hour rotation of the planet's magnetic field. By contrast, the reverse is true for the polar regions where the rotation period is 12 hours. This differential rotation is the most pronounced of any planet in the Solar System,[120] and it results in strong latitudinal wind shear.[84]

Orbital resonances

Main articles: Kuiper belt, resonant trans-Neptunian object, and Neptune trojan
 
A diagram showing the major orbital resonances in the Kuiper belt caused by Neptune: the highlighted regions are the 2:3 resonance (plutinos), the nonresonant "classical belt" (cubewanos), and the 1:2 resonance (twotinos).

Neptune's orbit has a profound impact on the region directly beyond it, known as the Kuiper belt. The Kuiper belt is a ring of small icy worlds, similar to the asteroid belt but far larger, extending from Neptune's orbit at 30 AU out to about 55 AU from the Sun.[121] Much in the same way that Jupiter's gravity dominates the asteroid belt, shaping its structure, so Neptune's gravity dominates the Kuiper belt. Over the age of the Solar System, certain regions of the Kuiper belt became destabilised by Neptune's gravity, creating gaps in its structure. The region between 40 and 42 AU is an example.[122]

There do exist orbits within these empty regions where objects can survive for the age of the Solar System. These resonances occur when Neptune's orbital period is a precise fraction of that of the object, such as 1:2, or 3:4. If, say, an object orbits the Sun once for every two Neptune orbits, it will only complete half an orbit by the time Neptune returns to its original position. The most heavily populated resonance in the Kuiper belt, with over 200 known objects,[123] is the 2:3 resonance. Objects in this resonance complete 2 orbits for every 3 of Neptune, and are known as plutinos because the largest of the known Kuiper belt objects, Pluto, is among them.[124] Although Pluto crosses Neptune's orbit regularly, the 2:3 resonance ensures they can never collide.[125] The 3:4, 3:5, 4:7 and 2:5 resonances are less populated.[126]

Neptune has a number of known trojan objects occupying both the Sun–Neptune L4 and L5 Lagrangian points—gravitationally stable regions leading and trailing Neptune in its orbit, respectively.[127] Neptune trojans can be viewed as being in a 1:1 resonance with Neptune. Some Neptune trojans are remarkably stable in their orbits, and are likely to have formed alongside Neptune rather than being captured. The first object identified as associated with Neptune's trailing L5 Lagrangian point was 2008 LC18.[128] Neptune also has a temporary quasi-satellite, (309239) 2007 RW10.[129] The object has been a quasi-satellite of Neptune for about 12,500 years and it will remain in that dynamical state for another 12,500 years.[129]

Formation and migration

Main articles: Formation and evolution of the Solar System and Nice model
 
A simulation showing the outer planets and Kuiper belt: a) before Jupiter and Saturn reached a 2:1 resonance; b) after inward scattering of Kuiper belt objects following the orbital shift of Neptune; c) after ejection of scattered Kuiper belt bodies by Jupiter

The formation of the ice giants, Neptune and Uranus, has proven difficult to model precisely. Current models suggest that the matter density in the outer regions of the Solar System was too low to account for the formation of such large bodies from the traditionally accepted method of core accretion, and various hypotheses have been advanced to explain their formation. One is that the ice giants were not formed by core accretion but from instabilities within the original protoplanetary disc and later had their atmospheres blasted away by radiation from a nearby massive OB star.[69]

An alternative concept is that they formed closer to the Sun, where the matter density was higher, and then subsequently migrated to their current orbits after the removal of the gaseous protoplanetary disc.[130] This hypothesis of migration after formation is favoured, due to its ability to better explain the occupancy of the populations of small objects observed in the trans-Neptunian region.[131] The current most widely accepted[132][133][134] explanation of the details of this hypothesis is known as the Nice model, which explores the effect of a migrating Neptune and the other giant planets on the structure of the Kuiper belt.

Moons

Main article: Moons of Neptune
For a timeline of discovery dates, see Timeline of discovery of Solar System planets and their moons.
 
An annotated picture of Neptune's many moons as captured by the James Webb Space Telescope. The bright blue diffraction star is Triton, Neptune's largest moon.

Neptune has 14 known moons.[7][135] Triton is the largest Neptunian moon, comprising more than 99.5% of the mass in orbit around Neptune,[h] and it is the only one massive enough to be spheroidal. Triton was discovered by William Lassell just 17 days after the discovery of Neptune itself. Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt.[136] It is close enough to Neptune to be locked into a synchronous rotation, and it is slowly spiralling inward because of tidal acceleration. It will eventually be torn apart, in about 3.6 billion years, when it reaches the Roche limit.[137] In 1989, Triton was the coldest object that had yet been measured in the Solar System,[138] with estimated temperatures of 38 K (−235 °C).[139]

Neptune's second-known satellite (by order of discovery), the irregular moon Nereid, has one of the most eccentric orbits of any satellite in the Solar System. The eccentricity of 0.7512 gives it an apoapsis that is seven times its periapsis distance from Neptune.[i]

From July to September 1989, Voyager 2 discovered six moons of Neptune.[140] Of these, the irregularly shaped Proteus is notable for being as large as a body of its density can be without being pulled into a spherical shape by its own gravity.[141] Although the second-most-massive Neptunian moon, it is only 0.25% the mass of Triton. Neptune's innermost four moons—Naiad, Thalassa, Despina and Galatea—orbit close enough to be within Neptune's rings. The next-farthest out, Larissa, was originally discovered in 1981 when it had occulted a star. This occultation had been attributed to ring arcs, but when Voyager 2 observed Neptune in 1989, Larissa was found to have caused it. Five new irregular moons discovered between 2002 and 2003 were announced in 2004.[142][143] A new moon and the smallest yet, Hippocamp, was found in 2013 by combining multiple Hubble images.[144] Because Neptune was the Roman god of the sea, Neptune's moons have been named after lesser sea gods.[50]

Planetary rings

Main article: Rings of Neptune
 
Neptune's rings and moons viewed in infrared by the James Webb Space Telescope

Neptune has a planetary ring system, though one much less substantial than that of Saturn.[145] The rings may consist of ice particles coated with silicates or carbon-based material, which most likely gives them a reddish hue.[146] The three main rings are the narrow Adams Ring, 63,000 km from the centre of Neptune, the Le Verrier Ring, at 53,000 km, and the broader, fainter Galle Ring, at 42,000 km. A faint outward extension to the Le Verrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57,000 km.[147]

The first of these planetary rings was detected in 1968 by a team led by Edward Guinan.[30][148] In the early 1980s, analysis of this data along with newer observations led to the hypothesis that this ring might be incomplete.[149] Evidence that the rings might have gaps first arose during a stellar occultation in 1984 when the rings obscured a star on immersion but not on emersion.[150] Images from Voyager 2 in 1989 settled the issue by showing several faint rings.

The outermost ring, Adams, contains five prominent arcs now named Courage, Liberté, Egalité 1, Egalité 2 and Fraternité (Courage, Liberty, Equality and Fraternity).[151] The existence of arcs was difficult to explain because the laws of motion would predict that arcs would spread out into a uniform ring over short timescales. Astronomers now estimate that the arcs are corralled into their current form by the gravitational effects of Galatea, a moon just inward from the ring.[152][153]

Earth-based observations announced in 2005 appeared to show that Neptune's rings were much more unstable than previously thought. Images taken from the W. M. Keck Observatory in 2002 and 2003 show considerable decay in the rings when compared to images by Voyager 2. In particular, it seems that the Liberté arc might disappear in as little as one century.[154]

Observation

 
Movement of Neptune in front of the stars of Aquarius in 2022
 
In 2018, the European Southern Observatory used adaptive optics to get clear and high-resolution images of Neptune from the surface of Earth.

Neptune brightened about 10% between 1980 and 2000 mostly due to the changing of the seasons.[155] Neptune may continue to brighten as it approaches perihelion in 2042. The apparent magnitude currently ranges from 7.67 to 7.89 with a mean of 7.78 and a standard deviation of 0.06.[15] Prior to 1980, the planet was as faint as magnitude 8.0.[15] Neptune is too faint to be visible to the naked eye. It can be outshone by Jupiter's Galilean moons, the dwarf planet Ceres and the asteroids 4 Vesta, 2 Pallas, 7 Iris, 3 Juno, and 6 Hebe.[156] A telescope or strong binoculars will resolve Neptune as a small blue disk, similar in appearance to Uranus.[157]

Because of the distance of Neptune from Earth, its angular diameter only ranges from 2.2 to 2.4 arcseconds,[7][17] the smallest of the Solar System planets. Its small apparent size makes it challenging to study visually. Most telescopic data was fairly limited until the advent of the Hubble Space Telescope and large ground-based telescopes with adaptive optics (AO).[158][159][160] The first scientifically useful observation of Neptune from ground-based telescopes using adaptive optics was commenced in 1997 from Hawaii.[161] Neptune is currently approaching perihelion (closest approach to the Sun) and has been shown to be heating up, with increased atmospheric activity and brightness as a consequence. Combined with technological advancements, ground-based telescopes with adaptive optics are recording increasingly more detailed images of it. Both Hubble and the adaptive-optics telescopes on Earth have made many new discoveries within the Solar System since the mid-1990s, with a large increase in the number of known satellites and moons around the outer planet, among others. In 2004 and 2005, five new small satellites of Neptune with diameters between 38 and 61 kilometres were discovered.[162]

From Earth, Neptune goes through apparent retrograde motion every 367 days, resulting in a looping motion against the background stars during each opposition. These loops carried it close to the 1846 discovery coordinates in April and July 2010 and again in October and November 2011.[118]

Neptune's 164-year orbital period means that the planet takes an average of 13 years to move through each constellation of the zodiac. In 2011, it completed its first full orbit of the Sun since being discovered and returned to where it was first spotted northeast of Iota Aquarii.[41]

Observation of Neptune in the radio-frequency band shows that it is a source of both continuous emission and irregular bursts. Both sources are thought to originate from its rotating magnetic field.[83] In the infrared part of the spectrum, Neptune's storms appear bright against the cooler background, allowing the size and shape of these features to be readily tracked.[163]

Exploration

Main article: Exploration of Neptune
 
A Voyager 2 mosaic of Triton

Voyager 2 is the only spacecraft that has visited Neptune. The spacecraft's closest approach to the planet occurred on 25 August 1989. Because this was the last major planet the spacecraft could visit, it was decided to make a close flyby of the moon Triton, regardless of the consequences to the trajectory, similarly to what was done for Voyager 1's encounter with Saturn and its moon Titan. The images relayed back to Earth from Voyager 2 became the basis of a 1989 PBS all-night program, Neptune All Night.[164]

During the encounter, signals from the spacecraft required 246 minutes to reach Earth. Hence, for the most part, Voyager 2's mission relied on preloaded commands for the Neptune encounter. The spacecraft performed a near-encounter with the moon Nereid before it came within 4,400 km of Neptune's atmosphere on 25 August, then passed close to the planet's largest moon Triton later the same day.[165]

The spacecraft verified the existence of a magnetic field surrounding the planet and discovered that the field was offset from the centre and tilted in a manner similar to the field around Uranus. Neptune's rotation period was determined using measurements of radio emissions and Voyager 2 also showed that Neptune had a surprisingly active weather system. Six new moons were discovered, and the planet was shown to have more than one ring.[140][165]

The flyby also provided the first accurate measurement of Neptune's mass which was found to be 0.5 percent less than previously calculated. The new figure disproved the hypothesis that an undiscovered Planet X acted upon the orbits of Neptune and Uranus.[166][167]

Since 2018, the China National Space Administration has been studying a concept for a pair of Voyager-like interstellar probes tentatively known as Interstellar Express or Interstellar Heliosphere Probe.[168] Both probes will be launched at the same time in 2024 and take differing paths to explore opposing ends of the heliosphere; the second probe, IHP-2, will fly by Neptune in January 2038, passing only 1,000 km above the cloud tops, and potentially carry an atmospheric impactor to be released during its approach.[169] Afterward, it will continue on its mission throughout the Kuiper belt toward the tail of the heliosphere, so far unexplored.

After Voyager 2 and IHP-2's flybys, the next step in scientific exploration of the Neptunian system is considered to be an orbital mission; most proposals have been by NASA, most often for a Flagship orbiter.[170] Such a hypothetical mission is envisioned to be possible in the late 2020s or early 2030s.[170] However, there have been discussions to launch Neptune missions sooner. In 2003, there was a proposal in NASA's "Vision Missions Studies" for a "Neptune Orbiter with Probes" mission that does Cassini-level science.[171] Another, more recent proposal was for Argo, a flyby spacecraft to be launched in 2019, that would visit Jupiter, Saturn, Neptune, and a Kuiper belt object. The focus would be on Neptune and its largest moon Triton to be investigated around 2029.[172] The proposed New Horizons 2 mission (which was later scrapped) might also have done a close flyby of the Neptunian system. Currently a pending proposal for the Discovery program, Trident would conduct a flyby of Neptune and Triton;[173] however, the mission was not selected for Discovery 15 or 16. Neptune Odyssey is the current mission concept for a Neptune orbiter and atmospheric probe being studied as a possible large strategic science mission by NASA that would launch between 2031 and 2033, and arrive at Neptune by 2049.[174]

See also

Notes

  1. ^ Orbital elements refer to the Neptune barycentre and Solar System barycentre. These are the instantaneous osculating values at the precise J2000 epoch. Barycentre quantities are given because, in contrast to the planetary centre, they do not experience appreciable changes on a day-to-day basis from the motion of the moons.
  2. ^ a b c d e f g Refers to the level of 1 bar (100 kPa) atmospheric pressure
  3. ^ Based on the volume within the level of 1 bar atmospheric pressure
  4. ^ A second symbol, an ‘LV’ monogram   for 'Le Verrier', analogous to the ‘H’ monogram   for Uranus. It was never much used outside of France and is now archaic.
  5. ^ One might be tempted to say "except 'Earth'", which in the English language is the name of a Germanic deity, Erda. The IAU policy is that one may call the Earth and the Moon by any name commonly used in the language being used. Contrary to common use by science fiction writers, 'Terra' and 'Luna' are not the official names of planet Earth and its moon. See the wikipedia article Earth for references.
  6. ^ The mass of Earth is 5.9736×1024 kg, giving a mass ratio
     
    The mass of Uranus is 8.6810×1025 kg, giving a mass ratio
     
    The mass of Jupiter is 1.8986×1027 kg, giving a mass ratio
     
    Mass values from Williams, David R. (29 November 2007). "Planetary Fact Sheet – Metric". NASA. from the original on 5 September 2014. Retrieved 13 March 2008.
  7. ^ The last three aphelia were 30.33 AU, the next is 30.34 AU. The perihelia are even more stable at 29.81 AU.[115]
  8. ^ Mass of Triton: 2.14×1022 kg. Combined mass of 12 other known moons of Neptune: 7.53×1019 kg, or 0.35%. The mass of the rings is negligible.
  9. ^  

References

  1. ^ a b c Hamilton, Calvin J. (4 August 2001). . Views of the Solar System. Archived from the original on 15 July 2007. Retrieved 13 August 2007.
  2. ^ Walter, Elizabeth (21 April 2003). Cambridge Advanced Learner's Dictionary (2nd ed.). Cambridge University Press. ISBN 978-0-521-53106-1.
  3. ^ "Neptunian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  4. ^ a b (PDF). NASA. September 2004. Archived from the original (PDF) on 22 December 2016. Retrieved 26 January 2016.
  5. ^ Yeomans, Donald K. "HORIZONS Web-Interface for Neptune Barycenter (Major Body=8)". JPL Horizons On-Line Ephemeris System. from the original on 7 September 2021. Retrieved 18 July 2014.—Select "Ephemeris Type: Orbital Elements", "Time Span: 2000-01-01 12:00 to 2000-01-02". ("Target Body: Neptune Barycenter" and "Center: Solar System Barycenter (@0)".)
  6. ^ a b Seligman, Courtney. . Archived from the original on 28 July 2011. Retrieved 13 August 2009.
  7. ^ a b c d e f g h i j k l m n o p Williams, David R. (1 September 2004). "Neptune Fact Sheet". NASA. from the original on 1 July 2010. Retrieved 14 August 2007.
  8. ^ 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.
  9. ^ "HORIZONS Planet-center Batch call for September 2042 Perihelion". ssd.jpl.nasa.gov (Perihelion for Neptune's planet-center (899) occurs on 2042-Sep-04 at 29.80647406au during a rdot flip from negative to positive). NASA/JPL. from the original on 7 September 2021. Retrieved 7 September 2021.
  10. ^ a b c d e f Seidelmann, P. Kenneth; Archinal, Brent A.; A'Hearn, Michael F.; Conrad, Albert R.; Consolmagno, Guy J.; Hestroffer, Daniel; et al. (2007). "Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006". Celestial Mechanics and Dynamical Astronomy. 98 (3): 155–180. Bibcode:2007CeMDA..98..155S. doi:10.1007/s10569-007-9072-y.
  11. ^ a b c Munsell, K.; Smith, H.; Harvey, S. (13 November 2007). . NASA. Archived from the original on 9 April 2014. Retrieved 14 August 2007.
  12. ^ 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. from the original on 26 November 2016. Retrieved 17 August 2016.
  13. ^ Pearl, J.C.; et al. (1991). "The albedo, effective temperature, and energy balance of Neptune, as determined from Voyager data". Journal of Geophysical Research. 96: 18, 921–930. Bibcode:1991JGR....9618921P. doi:10.1029/91JA01087.
  14. ^ Mallama, Anthony; Krobusek, Bruce; Pavlov, Hristo (2017). "Comprehensive wide-band magnitudes and albedos for the planets, with applications to exo-planets and Planet Nine". Icarus. 282: 19–33. arXiv:1609.05048. Bibcode:2017Icar..282...19M. doi:10.1016/j.icarus.2016.09.023. S2CID 119307693.
  15. ^ a b c d 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.
  16. ^ "Encyclopedia - the brightest bodies". IMCCE. Retrieved 29 May 2023.
  17. ^ a b Espenak, Fred (20 July 2005). "Twelve Year Planetary Ephemeris: 1995–2006". NASA. Archived from the original on 5 December 2012. Retrieved 1 March 2008.
  18. ^ Chang, Kenneth (18 October 2014). "Dark Spots in Our Knowledge of Neptune". The New York Times. from the original on 28 October 2014. Retrieved 21 October 2014.
  19. ^ "Exploration | Neptune". NASA Solar System Exploration. from the original on 17 July 2020. Retrieved 3 February 2020. In 1989, NASA's Voyager 2 became the first-and only-spacecraft to study Neptune up close.
  20. ^ Podolak, M.; Weizman, A.; Marley, M. (December 1995). "Comparative models of Uranus and Neptune". Planetary and Space Science. 43 (12): 1517–1522. Bibcode:1995P&SS...43.1517P. doi:10.1016/0032-0633(95)00061-5.
  21. ^ a b c d e f g h i j Lunine, Jonathan I. (September 1993). "The atmospheres of Uranus and Neptune". Annual Review of Astronomy and Astrophysics. 31: 217–263. Bibcode:1993ARA&A..31..217L. doi:10.1146/annurev.aa.31.090193.001245.
  22. ^ Munsell, Kirk; Smith, Harman; Harvey, Samantha (13 November 2007). . Solar System Exploration. NASA. Archived from the original on 3 March 2008. Retrieved 20 February 2008.
  23. ^ info@noirlab.edu. "Gemini North Telescope Helps Explain Why Uranus and Neptune Are Different Colors - Observations from Gemini Observatory, a Program of NSF's NOIRLab, and other telescopes reveal that excess haze on Uranus makes it paler than Neptune". www.noirlab.edu. Retrieved 30 July 2022.
  24. ^ Laboratory, By NSF’s NOIRLab (National Optical-Infrared Astronomy Research. "Why Uranus and Neptune Are Different Colors". NASA Solar System Exploration. Retrieved 6 March 2023.
  25. ^ Magazine, Smithsonian; Kuta, Sarah. "Why Neptune Appears Bluer Than Its Cousin Uranus". Smithsonian Magazine. Retrieved 30 July 2022.
  26. ^ a b Shannon Stirone (22 December 2020). "Neptune's Weird Dark Spot Just Got Weirder – While observing the planet's large inky storm, astronomers spotted a smaller vortex they named Dark Spot Jr". The New York Times. from the original on 22 December 2020. Retrieved 22 December 2020.
  27. ^ a b Suomi, V.E.; Limaye, S.S.; Johnson, D.R. (1991). "High Winds of Neptune: A possible mechanism". Science. 251 (4996): 929–32. Bibcode:1991Sci...251..929S. doi:10.1126/science.251.4996.929. PMID 17847386. S2CID 46419483.
  28. ^ a b c d e Hubbard, W.B. (1997). "Neptune's Deep Chemistry". Science. 275 (5304): 1279–80. doi:10.1126/science.275.5304.1279. PMID 9064785. S2CID 36248590.
  29. ^ a b Nettelmann, N.; French, M.; Holst, B.; Redmer, R. (PDF). University of Rostock. Archived from the original (PDF) on 18 July 2011. Retrieved 25 February 2008.
  30. ^ a b Wilford, John N. (10 June 1982). "Data Shows 2 Rings Circling Neptune". The New York Times. from the original on 10 December 2008. Retrieved 29 February 2008.
  31. ^ Hirschfeld, Alan (2001). Parallax: The Race to Measure the Cosmos. New York, New York: Henry Holt. ISBN 978-0-8050-7133-7.
  32. ^ Littmann, Mark; Standish, E.M. (2004). Planets Beyond: Discovering the Outer Solar System. Courier Dover Publications. ISBN 978-0-486-43602-9.
  33. ^ Britt, Robert Roy (2009). "Galileo discovered Neptune, new theory claims". NBC News News. from the original on 4 November 2013. Retrieved 10 July 2009.
  34. ^ Bouvard, A. (1821). Tables astronomiques publiées par le Bureau des Longitudes de France. Paris: Bachelier.
  35. ^ a b c Airy, G.B. (13 November 1846). "Account of some circumstances historically connected with the discovery of the planet exterior to Uranus". Monthly Notices of the Royal Astronomical Society. 7 (10): 121–44. Bibcode:1846MNRAS...7..121A. doi:10.1002/asna.18470251002. from the original on 29 September 2021. Retrieved 12 June 2019.
  36. ^ O'Connor, John J.; Robertson, Edmund F. (2006). "John Couch Adams' account of the discovery of Neptune". University of St Andrews. from the original on 26 January 2008. Retrieved 18 February 2008.
  37. ^ Adams, J.C. (13 November 1846). "Explanation of the observed irregularities in the motion of Uranus, on the hypothesis of disturbance by a more distant planet". Monthly Notices of the Royal Astronomical Society. 7 (9): 149–52. Bibcode:1846MNRAS...7..149A. doi:10.1093/mnras/7.9.149. (PDF) from the original on 2 May 2019. Retrieved 25 August 2019.
  38. ^ Challis, Rev. J. (13 November 1846). "Account of observations at the Cambridge observatory for detecting the planet exterior to Uranus". Monthly Notices of the Royal Astronomical Society. 7 (9): 145–149. Bibcode:1846MNRAS...7..145C. doi:10.1093/mnras/7.9.145. (PDF) from the original on 4 May 2019. Retrieved 25 August 2019.
  39. ^ Sack, Harald (12 December 2017). "James Challis and his failure to discover the planet Neptune". scihi.org. Retrieved 15 November 2021.
  40. ^ Galle, J.G. (13 November 1846). "Account of the discovery of the planet of Le Verrier at Berlin". Monthly Notices of the Royal Astronomical Society. 7 (9): 153. Bibcode:1846MNRAS...7..153G. doi:10.1093/mnras/7.9.153.
  41. ^ a b Gaherty, Geoff (12 July 2011). "Neptune Completes First Orbit Since Its Discovery in 1846". space.com. from the original on 25 August 2019. Retrieved 3 September 2019.
  42. ^ Levenson, Thomas (2015). The Hunt for Vulcan ... and how Albert Einstein Destroyed a Planet, Discovered Relativity, and Deciphered the Universe. Random House. p. 38.
  43. ^ Kollerstrom, Nick (2001). . University College London. Archived from the original on 11 November 2005. Retrieved 19 March 2007.
  44. ^ William Sheehan; Nicholas Kollerstrom; Craig B. Waff (December 2004). "The case of the pilfered planet – did the British steal Neptune?". Scientific American. from the original on 19 March 2011. Retrieved 20 January 2011.
  45. ^ Moore (2000):206
  46. ^ Littmann, Mark (2004). Planets Beyond, Exploring the Outer Solar System. Courier Dover Publications. p. 50. ISBN 978-0-486-43602-9.
  47. ^ Baum, Richard; Sheehan, William (2003). In Search of Planet Vulcan: The ghost in Newton's clockwork universe. Basic Books. pp. 109–10. ISBN 978-0-7382-0889-3.
  48. ^ Gingerich, Owen (October 1958). "The naming of Uranus and Neptune". Astronomical Society of the Pacific Leaflets. 8 (352): 9–15. Bibcode:1958ASPL....8....9G.
  49. ^ Hind, J.R. (1847). "Second report of proceedings in the Cambridge Observatory relating to the new Planet (Neptune)". Astronomische Nachrichten. 25 (21): 309–14. Bibcode:1847AN.....25..309.. doi:10.1002/asna.18470252102. from the original on 29 September 2021. Retrieved 12 June 2019.
  50. ^ a b "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. U.S. Geological Survey. 17 December 2008. from the original on 9 August 2018. Retrieved 26 March 2012.
  51. ^ "Planetary linguistics". nineplanets.org. from the original on 7 April 2010. Retrieved 8 April 2010.
  52. ^ "Sao Hải Vương – "Cục băng" khổng lồ xa tít tắp" (in Vietnamese). Kenh14. 31 October 2010. from the original on 30 July 2018. Retrieved 30 July 2018.
  53. ^ "Greek Names of the Planets". 25 April 2010. from the original on 9 May 2010. Retrieved 14 July 2012. Neptune or Poseidon as is its Greek name, was the God of the Seas. It is the eight planet from the sun ...
  54. ^ Ettinger, Yair (31 December 2009). "Uranus and Neptune get Hebrew names at last". Haaretz. from the original on 25 June 2018. Retrieved 16 August 2018.
  55. ^ Belizovsky, Avi (31 December 2009). "אוראנוס הוא מהיום אורון ונפטון מעתה רהב" [Uranus is now Oron and Neptune is now Rahav]. Hayadan (in Hebrew). from the original on 24 June 2018. Retrieved 16 August 2018.
  56. ^ a b "Appendix 5: Planetary Linguistics" 19 April 2010 at the Wayback Machine, Nineplanets.org
  57. ^ Mohamed Kadir (1975). "Waruna". Kamus Kebangsaan Ejaan Baru, Inggeris-bahasa Malaysia, Bahasa Malaysia-Inggeris. Titiwangsa. pp. 299, 857. from the original on 29 September 2021. Retrieved 29 May 2021.
  58. ^ "Neptun". Kamus Dewan (4th ed.). Dewan Bahasa dan Pustaka Malaysia. 2017. from the original on 7 May 2021. Retrieved 5 May 2021.
  59. ^ "Neptunus". Kamus Besar Bahasa Indonesia (3rd ed.). Badan Pengembangan dan Pembinaan Bahasa Indonesia. 2016. from the original on 29 September 2021. Retrieved 5 May 2021.
  60. ^ The Century Dictionary (1914)
  61. ^ Long, Tony (21 January 2008). "Jan. 21, 1979: Neptune Moves Outside Pluto's Wacky Orbit". Wired. from the original on 27 March 2008. Retrieved 13 March 2008.
  62. ^ Space com Staff (17 November 2006). "Neptune Data Sheet". Space.com.
  63. ^ Stern, Alan; Tholen, David James (1997). Pluto and Charon. University of Arizona Press. pp. 206–208. ISBN 978-0-8165-1840-1.
  64. ^ Weissman, Paul R. (1995). "The Kuiper Belt". Annual Review of Astronomy and Astrophysics. 33: 327–57. Bibcode:1995ARA&A..33..327W. doi:10.1146/annurev.aa.33.090195.001551.
  65. ^ . International Astronomical Union, Press release. 1999. Archived from the original on 15 June 2006. Retrieved 25 May 2006.
  66. ^ "IAU 2006 General Assembly: Resolutions 5 and 6" (PDF). IAU. 24 August 2006. (PDF) from the original on 25 June 2008. Retrieved 22 July 2008.
  67. ^ "Neptune Fact Sheet". NASA. from the original on 1 July 2010. Retrieved 22 September 2005.
  68. ^ Unsöld, Albrecht; Baschek, Bodo (2001). The New Cosmos: An introduction to astronomy and astrophysics (5th ed.). Springer. Table 3.1, page 47. Bibcode:2001ncia.book.....U. ISBN 978-3-540-67877-9.
  69. ^ a b Boss, Alan P. (2002). "Formation of gas and ice giant planets". Earth and Planetary Science Letters. 202 (3–4): 513–23. Bibcode:2002E&PSL.202..513B. doi:10.1016/S0012-821X(02)00808-7.
  70. ^ Lovis, C.; Mayor, M.; Alibert Y.; Benz W. (18 May 2006). "Trio of Neptunes and their Belt". ESO. from the original on 13 January 2010. Retrieved 25 February 2008.
  71. ^ Atreya, S.; Egeler, P.; Baines, K. (2006). "Water-ammonia ionic ocean on Uranus and Neptune?" (PDF). Geophysical Research Abstracts. 8. 05179. (PDF) from the original on 5 February 2012. Retrieved 7 November 2007.
  72. ^ Shiga, David (1 September 2010). "Weird water lurking inside giant planets". New Scientist. No. 2776. from the original on 12 February 2018. Retrieved 11 February 2018.
  73. ^ Kerr, Richard A. (October 1999). "Neptune May Crush Methane into Diamonds". Science. 286 (5437): 25a–25. doi:10.1126/science.286.5437.25a. PMID 10532884. S2CID 42814647.
  74. ^ a b Kaplan, Sarah (25 August 2017). "It rains solid diamonds on Uranus and Neptune". The Washington Post. from the original on 27 August 2017. Retrieved 27 August 2017.
  75. ^ Kraus, D.; et al. (September 2017). "Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions". Nature Astronomy. 1 (9): 606–11. Bibcode:2017NatAs...1..606K. doi:10.1038/s41550-017-0219-9. S2CID 46945778. from the original on 23 October 2018. Retrieved 25 August 2018.
  76. ^ Sean Kane (29 April 2016). "Lightning storms make it rain diamonds on Saturn and Jupiter". Business Insider. from the original on 26 June 2019. Retrieved 22 May 2019.
  77. ^ Baldwin, Emily (21 January 2010). . Astronomy Now. Archived from the original on 3 December 2013.
  78. ^ Bradley, D.K.; Eggert, J.H.; Hicks, D.G.; Celliers, P.M. (30 July 2004). (PDF). Physical Review Letters. 93 (19): 195506. Bibcode:2004PhRvL..93s5506B. doi:10.1103/physrevlett.93.195506. hdl:1959.3/380076. PMID 15600850. S2CID 6203103. Archived from the original (PDF) on 21 December 2016. Retrieved 16 March 2016.
  79. ^ Eggert, J.H.; Hicks, D.G.; Celliers, P.M.; Bradley, D.K.; et al. (8 November 2009). "Melting temperature of diamond at ultrahigh pressure". Nature Physics. 6 (40): 40–43. Bibcode:2010NatPh...6...40E. doi:10.1038/nphys1438.
  80. ^ Podolak, M.; Weizman, A.; Marley, M. (1995). "Comparative models of Uranus and Neptune". Planetary and Space Science. 43 (12): 1517–22. Bibcode:1995P&SS...43.1517P. doi:10.1016/0032-0633(95)00061-5.
  81. ^ Crisp, D.; Hammel, H.B. (14 June 1995). "Hubble Space Telescope Observations of Neptune". Hubble News Center. from the original on 2 August 2007. Retrieved 22 April 2007.
  82. ^ a b c Andrews, Robin George (18 August 2023). "Neptune's Clouds Have Vanished, and Scientists Think They Know Why - A recent study suggests a relationship between solar cycles and the atmosphere of the solar system's eighth planet". The New York Times. Archived from the original on 18 August 2023. Retrieved 21 August 2023.
  83. ^ a b c d e Elkins-Tanton, Linda T. (2006). Uranus, Neptune, Pluto, and the Outer Solar System. New York: Chelsea House. pp. 79–83. ISBN 978-0-8160-5197-7.
  84. ^ a b c Max, C.E.; Macintosh, B.A.; Gibbard, S.G.; Gavel, D.T.; et al. (2003). "Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics". The Astronomical Journal. 125 (1): 364–75. Bibcode:2003AJ....125..364M. doi:10.1086/344943.
  85. ^ Gianopoulos, Andrea (16 August 2023). "Neptune's Disappearing Clouds Linked to the Solar Cycle". NASA. Retrieved 24 August 2023.
  86. ^ Chavez, Erandi; de Pater, Imke; Redwing, Erin; Molter, Edward M.; Roman, Michael T.; Zorzi, Andrea; Alvarez, Carlos; Campbell, Randy; de Kleer, Katherine; Hueso, Ricardo; Wong, Michael H.; Gates, Elinor; Lynam, Paul David; Davies, Ashley G.; Aycock, Joel; Mcilroy, Jason; Pelletier, John; Ridenour, Anthony; Stickel, Terry (1 November 2023). "Evolution of Neptune at near-infrared wavelengths from 1994 through 2022". Icarus. 404: 115667. arXiv:2307.08157. Bibcode:2023Icar..40415667C. doi:10.1016/j.icarus.2023.115667. ISSN 0019-1035. S2CID 259515455. Retrieved 24 August 2023. The clear positive correlation we find between cloud activity and Solar Lyman-Alpha (121.56 nm) irradiance lends support to the theory that the periodicity in Neptune's cloud activity results from photochemical cloud/haze production triggered by Solar ultraviolet emissions.
  87. ^ a b Encrenaz, Thérèse (February 2003). "ISO observations of the giant planets and Titan: What have we learnt?". Planetary and Space Science. 51 (2): 89–103. Bibcode:2003P&SS...51...89E. doi:10.1016/S0032-0633(02)00145-9.
  88. ^ Broadfoot, A.L.; Atreya, S.K.; Bertaux, J.L.; et al. (1999). "Ultraviolet Spectrometer Observations of Neptune and Triton" (PDF). Science. 246 (4936): 1459–66. Bibcode:1989Sci...246.1459B. doi:10.1126/science.246.4936.1459. PMID 17756000. S2CID 21809358. (PDF) from the original on 28 May 2008. Retrieved 12 March 2008.
  89. ^ Herbert, Floyd; Sandel, Bill R. (August–September 1999). "Ultraviolet observations of Uranus and Neptune". Planetary and Space Science. 47 (8–9): 1, 119–139. Bibcode:1999P&SS...47.1119H. doi:10.1016/S0032-0633(98)00142-1.
  90. ^ Stanley, Sabine; Bloxham, Jeremy (11 March 2004). "Convective-region geometry as the cause of Uranus' and Neptune's unusual magnetic fields". Nature. 428 (6979): 151–53. Bibcode:2004Natur.428..151S. doi:10.1038/nature02376. PMID 15014493. S2CID 33352017.
  91. ^ Connerney, J.E.P.; Acuña, Mario H.; Ness, Norman F. (1991). "The magnetic field of Neptune". Journal of Geophysical Research. 96: 19, 023–42. Bibcode:1991JGR....9619023C. doi:10.1029/91JA01165.
  92. ^ a b Ness, N.F.; Acuña, M.H.; Burlaga, L.F.; Connerney, J.E.P.; Lepping, R.P.; Neubauer, F.M. (1989). "Magnetic Fields at Neptune". Science. 246 (4936): 1473–78. Bibcode:1989Sci...246.1473N. doi:10.1126/science.246.4936.1473. PMID 17756002. S2CID 20274953. (PDF) from the original on 10 July 2019. Retrieved 25 August 2019.
  93. ^ Russell, C.T.; Luhmann, J.G. (1997). "Neptune: Magnetic Field and Magnetosphere". University of California, Los Angeles. from the original on 29 June 2019. Retrieved 10 August 2006.
  94. ^ Lavoie, Sue (8 January 1998). "PIA01142: Neptune Scooter". NASA. from the original on 29 October 2013. Retrieved 26 March 2006.
  95. ^ Hammel, H.B.; Beebe, R.F.; De Jong, E.M.; Hansen, C.J.; et al. (1989). "Neptune's wind speeds obtained by tracking clouds in Voyager 2 images". Science. 24 (4924): 1367–69. Bibcode:1989Sci...245.1367H. doi:10.1126/science.245.4924.1367. PMID 17798743. S2CID 206573894.
  96. ^ a b Burgess (1991):64–70.
  97. ^ a b Lavoie, Sue (16 February 2000). "PIA02245: Neptune's blue-green atmosphere". NASA JPL. from the original on 5 August 2013. Retrieved 28 February 2008.
  98. ^ Orton, G.S.; Encrenaz T.; Leyrat C.; Puetter, R.; et al. (2007). "Evidence for methane escape and strong seasonal and dynamical perturbations of Neptune's atmospheric temperatures". Astronomy and Astrophysics. 473 (1): L5–L8. Bibcode:2007A&A...473L...5O. doi:10.1051/0004-6361:20078277. S2CID 54996279.
  99. ^ Orton, Glenn; Encrenaz, Thérèse (18 September 2007). "A Warm South Pole? Yes, On Neptune!". ESO. from the original on 23 March 2010. Retrieved 20 September 2007.
  100. ^ a b Villard, Ray; Devitt, Terry (15 May 2003). "Brighter Neptune Suggests A Planetary Change of Seasons". Hubble News Center. Retrieved 26 February 2008.
  101. ^ 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): 1740–42. Bibcode:1995Sci...268.1740H. doi:10.1126/science.268.5218.1740. PMID 17834994. S2CID 11688794.
  102. ^ Lavoie, Sue (29 January 1996). "PIA00064: Neptune's Dark Spot (D2) at High Resolution". NASA JPL. from the original on 27 September 2013. Retrieved 28 February 2008.
  103. ^ information@eso.org. "Mysterious Neptune dark spot detected from Earth for the first time". www.eso.org. Retrieved 26 August 2023.
  104. ^ S.G., Gibbard; de Pater, I.; Roe, H.G.; Martin, S.; et al. (2003). (PDF). Icarus. 166 (2): 359–74. Bibcode:2003Icar..166..359G. doi:10.1016/j.icarus.2003.07.006. Archived from the original (PDF) on 20 February 2012. Retrieved 26 February 2008.
  105. ^ Stratman, P.W.; Showman, A.P.; Dowling, T.E.; Sromovsky, L.A. (2001). "EPIC Simulations of Bright Companions to Neptune's Great Dark Spots" (PDF). Icarus. 151 (2): 275–85. Bibcode:1998Icar..132..239L. doi:10.1006/icar.1998.5918. (PDF) from the original on 27 February 2008. Retrieved 26 February 2008.
  106. ^ 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. Bibcode:2000DPS....32.0903S.
  107. ^ "A storm is coming". spacetelescope.org. from the original on 20 February 2019. Retrieved 19 February 2019.
  108. ^ Michael H. Wong; Amy Simon (15 December 2020). "Dark Storm on Neptune Reverses Direction, Possibly Shedding Fragment". Hubblesite. from the original on 25 December 2020. Retrieved 25 December 2020.
  109. ^ "Neptune's shrinking vortex". spacetelescope.org. from the original on 19 February 2018. Retrieved 19 February 2018.
  110. ^ "Happy birthday Neptune". ESA/Hubble. from the original on 15 July 2011. Retrieved 13 July 2011.
  111. ^ Lindal, Gunnar F. (1992). "The atmosphere of Neptune – an analysis of radio occultation data acquired with Voyager 2". Astronomical Journal. 103: 967–82. Bibcode:1992AJ....103..967L. doi:10.1086/116119.
  112. ^ "Class 12 – Giant Planets – Heat and Formation". 3750 – Planets, Moons & Rings. Colorado University, Boulder. 2004. from the original on 21 June 2008. Retrieved 13 March 2008.
  113. ^ Pearl, J.C.; Conrath, B.J. (1991). "The albedo, effective temperature, and energy balance of Neptune, as determined from Voyager data". Journal of Geophysical Research: Space Physics. 96: 18, 921–30. Bibcode:1991JGR....9618921P. doi:10.1029/91ja01087.
  114. ^ Imke de Pater and Jack J. Lissauer (2001), Planetary Sciences 29 September 2021 at the Wayback Machine, 1st edition, p. 224.
  115. ^ Meeus, Jean (1998). Astronomical Algorithms. Richmond, VA: Willmann-Bell. p. 273. Supplemented by further use of VSOP87.
  116. ^ McKie, Robin (9 July 2011). "Neptune's first orbit: a turning point in astronomy". The Guardian. from the original on 23 August 2016. Retrieved 15 December 2016.
  117. ^ Nancy Atkinson (26 August 2010). "Clearing the Confusion on Neptune's Orbit". Universe Today. from the original on 27 July 2011. Retrieved 10 July 2011. (Bill Folkner at JPL) 29 September 2021 at the Wayback Machine
  118. ^ a b Anonymous (16 November 2007). . Archived from the original on 2 May 2013. Retrieved 25 February 2008.—Numbers generated using the Solar System Dynamics Group, Horizons On-Line Ephemeris System.
  119. ^ Williams, David R. (6 January 2005). "Planetary Fact Sheets". NASA. from the original on 25 September 2008. Retrieved 28 February 2008.
  120. ^ Hubbard, W.B.; Nellis, W.J.; Mitchell, A.C.; Holmes, N.C.; et al. (1991). "Interior Structure of Neptune: Comparison with Uranus". Science. 253 (5020): 648–51. Bibcode:1991Sci...253..648H. doi:10.1126/science.253.5020.648. PMID 17772369. S2CID 20752830. from the original on 23 October 2018. Retrieved 12 June 2019.
  121. ^ Stern, S. Alan; Colwell, Joshua E. (1997). "Collisional Erosion in the Primordial Edgeworth-Kuiper Belt and the Generation of the 30–50 AU Kuiper Gap". The Astrophysical Journal. 490 (2): 879–82. Bibcode:1997ApJ...490..879S. doi:10.1086/304912.
  122. ^ Petit, Jean-Marc; Morbidelli, Alessandro; Valsecchi, Giovanni B. (1999). (PDF). Icarus. 141 (2): 367–87. Bibcode:1999Icar..141..367P. doi:10.1006/icar.1999.6166. Archived from the original (PDF) on 1 December 2007. Retrieved 23 June 2007.
  123. ^ "List of Transneptunian Objects". Minor Planet Center. Archived from the original on 27 October 2010. Retrieved 25 October 2010.
  124. ^ Jewitt, David (2004). "The Plutinos". UCLA. from the original on 19 April 2007. Retrieved 28 February 2008.
  125. ^ Varadi, F. (1999). "Periodic Orbits in the 3:2 Orbital Resonance and Their Stability". The Astronomical Journal. 118 (5): 2526–31. Bibcode:1999AJ....118.2526V. doi:10.1086/301088.
  126. ^ John Davies (2001). Beyond Pluto: Exploring the outer limits of the solar system. Cambridge University Press. p. 104. ISBN 978-0-521-80019-8.
  127. ^ Chiang, E.I.; Jordan, A.B.; Millis, R.L.; M.W. Buie; et al. (2003). "Resonance Occupation in the Kuiper Belt: Case Examples of the 5 : 2 and Trojan Resonances". The Astronomical Journal. 126 (1): 430–43. arXiv:astro-ph/0301458. Bibcode:2003AJ....126..430C. doi:10.1086/375207. S2CID 54079935.
  128. ^ Sheppard, Scott S.; Trujillo, Chadwick A. (10 September 2010). "Detection of a Trailing (L5) Neptune Trojan". Science. 329 (5997): 1304. Bibcode:2010Sci...329.1304S. doi:10.1126/science.1189666. PMID 20705814. S2CID 7657932.
  129. ^ a b De La Fuente Marcos, C. & De La Fuente Marcos, R. (2012). "(309239) 2007 RW10: a large temporary quasi-satellite of Neptune". Astronomy and Astrophysics Letters. 545 (2012): L9. arXiv:1209.1577. Bibcode:2012A&A...545L...9D. doi:10.1051/0004-6361/201219931. S2CID 118374080.
  130. ^ Thommes, Edward W.; Duncan, Martin J.; Levison, Harold F. (2002). "The formation of Uranus and Neptune among Jupiter and Saturn". The Astronomical Journal. 123 (5): 2862–83. arXiv:astro-ph/0111290. Bibcode:2002AJ....123.2862T. doi:10.1086/339975. S2CID 17510705.
  131. ^ Hansen, Kathryn (7 June 2005). "Orbital shuffle for early solar system". Geotimes. from the original on 27 September 2007. Retrieved 26 August 2007.
  132. ^ Crida, A. (2009). "Solar System Formation". Reviews in Modern Astronomy. Vol. 21. p. 3008. arXiv:0903.3008. Bibcode:2009RvMA...21..215C. doi:10.1002/9783527629190.ch12. ISBN 978-3-527-62919-0.
  133. ^ Desch, S.J. (2007). (PDF). The Astrophysical Journal. 671 (1): 878–93. Bibcode:2007ApJ...671..878D. doi:10.1086/522825. S2CID 120903003. Archived from the original (PDF) on 7 February 2020.
  134. ^ Smith, R.; L.J. Churcher; M.C. Wyatt; M.M. Moerchen; et al. (2009). "Resolved debris disc emission around η Telescopii: a young solar system or ongoing planet formation?". Astronomy and Astrophysics. 493 (1): 299–308. arXiv:0810.5087. Bibcode:2009A&A...493..299S. doi:10.1051/0004-6361:200810706. S2CID 6588381.
  135. ^ Hubble Space Telescope discovers fourteenth tiny moon orbiting Neptune | Space, Military and Medicine 16 July 2013 at the Wayback Machine. News.com.au (16 July 2013). Retrieved on 28 July 2013.
  136. ^ Agnor, Craig B.; Hamilton, Douglas P. (2006). "Neptune's capture of its moon Triton in a binary–planet gravitational encounter". Nature. 441 (7090): 192–94. Bibcode:2006Natur.441..192A. doi:10.1038/nature04792. PMID 16688170. S2CID 4420518.
  137. ^ Chyba, Christopher F.; Jankowski, D.G.; Nicholson, P.D. (1989). "Tidal evolution in the Neptune-Triton system". Astronomy and Astrophysics. 219 (1–2): L23–L26. Bibcode:1989A&A...219L..23C.
  138. ^ Wilford, John N. (29 August 1989). "Triton May Be Coldest Spot in Solar System". The New York Times. from the original on 10 December 2008. Retrieved 29 February 2008.
  139. ^ 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. Bibcode:1990Sci...250..429N. doi:10.1126/science.250.4979.429. PMID 17793020. S2CID 20022185.
  140. ^ a b Stone, E.C.; Miner, E.D. (1989). "The Voyager 2 Encounter with the Neptunian System". Science. 246 (4936): 1417–21. Bibcode:1989Sci...246.1417S. doi:10.1126/science.246.4936.1417. PMID 17755996. S2CID 9367553.
  141. ^ Brown, Michael E. . California Institute of Technology, Department of Geological Sciences. Archived from the original on 19 July 2011. Retrieved 9 February 2008.
  142. ^ Holman, M.J.; Kavelaars, J.J.; Grav, T.; et al. (2004). "Discovery of five irregular moons of Neptune" (PDF). Nature. 430 (7002): 865–67. Bibcode:2004Natur.430..865H. doi:10.1038/nature02832. PMID 15318214. S2CID 4412380. (PDF) from the original on 2 November 2013. Retrieved 24 October 2011.
  143. ^ "Five new moons for planet Neptune". BBC News. 18 August 2004. from the original on 8 August 2007. Retrieved 6 August 2007.
  144. ^ Grush, Loren (20 February 2019). "Neptune's newly discovered moon may be the survivor of an ancient collision". The Verge. from the original on 21 February 2019. Retrieved 22 February 2019.
  145. ^ O"Callaghan, Jonathan (21 September 2022). "Neptune and Its Rings Come Into Focus With Webb Telescope - New images from the space-based observatory offer a novel view of the planet in infrared". The New York Times. Retrieved 23 September 2022.
  146. ^ Cruikshank, Dale P. (1996). Neptune and Triton. University of Arizona Press. pp. 703–804. ISBN 978-0-8165-1525-7.
  147. ^ Blue, Jennifer (8 December 2004). "Nomenclature Ring and Ring Gap Nomenclature". Gazetteer of Planetary Nomenclature. USGS. from the original on 5 July 2010. Retrieved 28 February 2008.
  148. ^ Guinan, E.F.; Harris, C.C.; Maloney, F.P. (1982). "Evidence for a Ring System of Neptune". Bulletin of the American Astronomical Society. 14: 658. Bibcode:1982BAAS...14..658G.
  149. ^ Goldreich, P.; Tremaine, S.; Borderies, N.E.F. (1986). "Towards a theory for Neptune's arc rings" (PDF). Astronomical Journal. 92: 490–94. Bibcode:1986AJ.....92..490G. doi:10.1086/114178. (PDF) from the original on 29 September 2021. Retrieved 12 June 2019.
  150. ^ Nicholson, P.D.; et al. (1990). "Five Stellar Occultations by Neptune: Further Observations of Ring Arcs". Icarus. 87 (1): 1–39. Bibcode:1990Icar...87....1N. doi:10.1016/0019-1035(90)90020-A.
  151. ^ Cox, Arthur N. (2001). Allen's Astrophysical Quantities. Springer. ISBN 978-0-387-98746-0.
  152. ^ Munsell, Kirk; Smith, Harman; Harvey, Samantha (13 November 2007). "Planets: Neptune: Rings". Solar System Exploration. NASA. from the original on 4 July 2012. Retrieved 29 February 2008.
  153. ^ Salo, Heikki; Hänninen, Jyrki (1998). "Neptune's Partial Rings: Action of Galatea on Self-Gravitating Arc Particles". Science. 282 (5391): 1102–04. Bibcode:1998Sci...282.1102S. doi:10.1126/science.282.5391.1102. PMID 9804544.
  154. ^ "Neptune's rings are fading away". New Scientist. 26 March 2005. from the original on 10 December 2008. Retrieved 6 August 2007.
  155. ^ Schmude, R.W., Jr.; Baker, R.E.; Fox, J.; Krobusek, B.A.; Pavlov, H.; Mallama, A. (29 March 2016). The secular and rotational brightness variations of Neptune (unpublished manuscript). arXiv:1604.00518.{{cite report}}: CS1 maint: multiple names: authors list (link)
  156. ^ See the respective articles for magnitude data.
  157. ^ Moore (2000):207.
  158. ^ In 1977, for example, even the rotation period of Neptune remained uncertain. Cruikshank, D.P. (1 March 1978). "On the rotation period of Neptune". Astrophysical Journal Letters. 220: L57–L59. Bibcode:1978ApJ...220L..57C. doi:10.1086/182636.
  159. ^ Max, C.; MacIntosh, B.; Gibbard, S.; Roe, H.; et al. (1999). "Adaptive Optics Imaging of Neptune and Titan with the W.M. Keck Telescope". Bulletin of the American Astronomical Society. 31: 1512. Bibcode:1999AAS...195.9302M.
  160. ^ Nemiroff, R.; Bonnell, J., eds. (18 February 2000). "Neptune through Adaptive Optics". Astronomy Picture of the Day. NASA.
  161. ^ First Ground-Based Adaptive Optics Observations of Neptune and Proteus 19 September 2017 at the Wayback Machine Planetary & Space Science Vol. 45, No. 8, pp. 1031–36, 1997
  162. ^ Uranus and Neptune Reports on Astronomy 2003–2005, pp. 147f.
  163. ^ Gibbard, S.G.; Roe, H.; de Pater, I.; Macintosh, B.; et al. (1999). "High-Resolution Infrared Imaging of Neptune from the Keck Telescope". Icarus. 156 (1): 1–15. Bibcode:2002Icar..156....1G. doi:10.1006/icar.2001.6766. from the original on 23 October 2018. Retrieved 12 June 2019.
  164. ^ Phillips, Cynthia (5 August 2003). . SETI Institute. Archived from the original on 3 November 2007. Retrieved 3 October 2007.
  165. ^ a b Burgess (1991):46–55.
  166. ^ Tom Standage (2000). The Neptune File: A Story of Astronomical Rivalry and the Pioneers of Planet Hunting. New York: Walker. p. 188. ISBN 978-0-8027-1363-6.
  167. ^ Chris Gebhardt; Jeff Goldader (20 August 2011). "Thirty-four years after launch, Voyager 2 continues to explore". NASASpaceflight. from the original on 19 February 2016. Retrieved 22 January 2016.
  168. ^ Wu, Weiren; Yu, Dengyun; Huang, Jiangchuan; Zong, Qiugang; Wang, Chi; Yu, Guobin; He, Rongwei; Wang, Qian; Kang, Yan; Meng, Linzhi; Wu, Ke; He, Jiansen; Li, Hui (9 January 2019). "Exploring the solar system boundary". Scientia Sinica Informationis. 49 (1): 1. doi:10.1360/N112018-00273. ISSN 2095-9486.
  169. ^ Jones, Andrew (16 April 2021). "China to launch a pair of spacecraft towards the edge of the solar system". SpaceNews. Archived from the original on 15 May 2021. Retrieved 29 April 2021.
  170. ^ a b Clark, Stephen (25 August 2015). "Uranus, Neptune in NASA's sights for new robotic mission". Spaceflight Now. from the original on 6 September 2015. Retrieved 7 September 2015.
  171. ^ Spilker, T.R.; Ingersoll, A.P. (2004). "Outstanding Science in the Neptune System From an Aerocaptured Vision Mission". Bulletin of the American Astronomical Society. 36: 1094. Bibcode:2004DPS....36.1412S.
  172. ^ Candice Hansen; et al. (PDF). SpacePolicyOnline.com. Space and Technology Policy Group, LLC. Archived from the original (PDF) on 24 September 2015. Retrieved 5 August 2015.
  173. ^ "Exploring Triton With Trident: A Discovery-Class Mission" (PDF). Universities Space Research Association. 23 March 2019. (PDF) from the original on 2 August 2020. Retrieved 26 March 2019.
  174. ^ Abigail Rymer; Brenda Clyde; Kirby Runyon (August 2020). "Neptune Odyssey: Mission to the Neptune-Triton System" (PDF). (PDF) from the original on 15 December 2020. Retrieved 18 April 2021.

Bibliography

Further reading

External links

 
Wikimedia Commons has media related to Neptune (planet).
  • NASA's Neptune fact sheet
  • Neptune from Bill Arnett's nineplanets.org
  • Neptune Astronomy Cast episode No. 63, includes full transcript.
  • (archived 15 November 2002) at NASA's Solar System Exploration site
  • Interactive 3D gravity simulation of Neptune and its inner moons 22 September 2020 at the Wayback Machine

October 03, 2023
neptune, this, article, about, planet, roman, mythology, other, uses, disambiguation, eighth, planet, redirects, here, other, systems, numbering, planets, planet, history, eighth, planet, from, farthest, recognized, planet, solar, system, fourth, largest, plan. This article is about the planet For the Roman god see Neptune mythology For other uses see Neptune disambiguation Eighth planet redirects here For other systems of numbering planets see Planet History Neptune is the eighth planet from the Sun and the farthest IAU recognized planet in the Solar System It is the fourth largest planet in the Solar System by diameter the third most massive planet and the densest giant planet It is 17 times the mass of Earth and slightly more massive than its near twin Uranus Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere Being composed primarily of gases and liquids it has no well defined solid surface The planet orbits the Sun once every 164 8 years at an average distance of 30 1 astronomical units 4 5 billion kilometres 2 8 billion miles It is named after the Roman god of the sea and has the astronomical symbol representing Neptune s trident d NeptunePhotograph taken by NASA s Voyager 2 in 1989Discovery 1 Discovered byJohann Galle Urbain Le Verrier John Couch AdamsDiscovery date23 September 1846DesignationsPronunciation ˈ n ɛ p tj uː n 2 Named afterLatin Neptunus via French NeptuneAdjectivesNeptunian n ɛ p ˈ tj uː n i en 3 Poseidean 4 Symbol historically alsoOrbital characteristics 5 a Epoch J2000Aphelion30 33 AU 4 54 billion km Perihelion29 81 AU 4 46 billion km Semi major axis30 07 AU 4 50 billion km Eccentricity0 008678Orbital period sidereal 164 8 yr 60 195 days 89 666 Neptunian solar days 6 Orbital period synodic 367 49 days 7 Average orbital speed5 43 km s 7 Mean anomaly259 883 Inclination1 770 to ecliptic6 43 to Sun s equator0 74 to invariable plane 8 Longitude of ascending node131 783 Time of perihelion2042 Sep 04 9 Argument of perihelion273 187 Known satellites14Physical characteristicsMean radius24 622 19 km 10 b Equatorial radius24 764 15 km 10 b 3 883 EarthsPolar radius24 341 30 km 10 b 3 829 EarthsFlattening0 0171 0 0013Surface area7 6187 109 km2 11 b 14 98 EarthsVolume6 253 1013 km3 7 b 57 74 EarthsMass1 02413 1026 kg 7 17 147 Earths5 15 10 5 SunsMean density1 638 g cm3 7 c Surface gravity11 15 m s2 7 b 1 14 gMoment of inertia factor0 23 12 estimate Escape velocity23 5 km s 7 b Synodic rotation period0 67125 d 16 h 6 m 36 s 6 Sidereal rotation period0 6713 day 7 16 h 6 min 36 sEquatorial rotation velocity2 68 km s 9 650 km h Axial tilt28 32 to orbit 7 North pole right ascension19h 57m 20s 10 299 3 North pole declination42 950 10 Albedo0 290 bond 13 0 442 geom 14 Surface temp min mean max1 bar level 72 K 201 C 7 0 1 bar 10 kPa 55 K 218 C 7 Apparent magnitude7 67 15 to 8 00 15 Absolute magnitude H 6 9 16 Angular diameter2 2 2 4 7 17 Atmosphere 7 Scale height19 7 0 6 kmComposition by volume80 3 2 hydrogen 19 3 2 helium 1 5 0 5 methane 0 019 hydrogen deuteride 0 00015 ethane Icy volatiles ammoniawater iceammonium hydrosulfidemethane ice Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical predictions rather than by empirical observation Unexpected changes in the orbit of Uranus led Alexis Bouvard to hypothesise that its orbit was subject to gravitational perturbation by an unknown planet After Bouvard s death the position of Neptune was predicted from his observations independently by John Couch Adams and Urbain Le Verrier Neptune was subsequently observed with a telescope on 23 September 1846 1 by Johann Galle within a degree of the position predicted by Le Verrier Its largest moon Triton was discovered shortly thereafter though none of the planet s remaining 14 known 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 Neptune was visited by Voyager 2 when it flew by the planet on 25 August 1989 Voyager 2 remains the only spacecraft to have visited Neptune 18 19 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 the gas giants Jupiter and Saturn Neptune s atmosphere is composed primarily of hydrogen and helium along with traces of hydrocarbons and possibly nitrogen but contains a higher proportion of ices such as water ammonia and methane Similar to Uranus its interior is primarily composed of ices and rock 20 both planets are normally considered ice giants to distinguish them 21 Along with Rayleigh scattering traces of methane in the outermost regions in part account for the planet s blue appearance 22 Newest data from the Gemini observatory shows the blue colour is more saturated than the one present on Uranus due to the thinner haze of Neptune s more active atmosphere 23 24 25 In contrast to the hazy relatively featureless atmosphere of Uranus Neptune s atmosphere has active and visible weather patterns 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 More recently in 2018 a newer main dark spot and smaller dark spot were identified and studied 26 In addition these weather patterns are driven by the strongest sustained winds of any planet in the Solar System with recorded wind speeds as high as 2 100 km h 580 m s 1 300 mph 27 Because of its great distance from the Sun Neptune 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 centre are approximately 5 400 K 5 100 C 9 300 F 28 29 Neptune has a faint and fragmented ring system labelled arcs which was discovered in 1984 then later confirmed by Voyager 2 30 Contents 1 History 1 1 Discovery 1 2 Naming 1 3 Status 2 Physical characteristics 2 1 Internal structure 2 2 Atmosphere 2 3 Magnetosphere 3 Climate 3 1 Storms 3 2 Internal heating 4 Orbit and rotation 4 1 Orbital resonances 5 Formation and migration 6 Moons 6 1 Planetary rings 7 Observation 8 Exploration 9 See also 10 Notes 11 References 12 Bibliography 13 Further reading 14 External linksHistoryDiscovery Main article Discovery of Neptune nbsp Galileo GalileiSome of the earliest recorded observations ever made through a telescope Galileo Galilei s drawings on 28 December 1612 and 27 January 1613 contain plotted points that match with what is now known to have been the positions of Neptune on those dates On both occasions Galileo seems to have mistaken Neptune for a fixed star when it appeared close in conjunction to Jupiter in the night sky 31 Hence he is not credited with Neptune s discovery At his first observation in December 1612 Neptune was almost stationary in the sky because it had just turned retrograde that day This apparent backward motion is created when Earth s orbit takes it past an outer planet Because Neptune was only beginning its yearly retrograde cycle the motion of the planet was far too slight to be detected with Galileo s small telescope 32 In 2009 a study suggested that Galileo was at least aware that the star he had observed had moved relative to fixed stars 33 In 1821 Alexis Bouvard published astronomical tables of the orbit of Neptune s neighbour Uranus 34 Subsequent observations revealed substantial deviations from the tables leading Bouvard to hypothesise that an unknown body was perturbing the orbit through gravitational interaction 35 In 1843 John Couch Adams began work on the orbit of Uranus using the data he had He requested extra data from Sir George Airy the Astronomer Royal who supplied it in February 1844 Adams continued to work in 1845 1846 and produced several different estimates of a new planet 36 37 nbsp Urbain Le VerrierIn 1845 1846 Urbain Le Verrier independently of Adams developed his own calculations but aroused no enthusiasm in his compatriots 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 Challis vainly scoured the sky throughout August and September 35 38 Challis had in fact observed Neptune a year before the planet s subsequent discoverer Johann Gottfried Galle and on two occasions 4 and 12 August 1845 However his out of date star maps and poor observing techniques meant that he failed to recognise the observations as such until he carried out later analysis Challis was full of remorse but blamed his neglect on his maps and the fact that he was distracted by his concurrent work on comet observations 39 35 40 Meanwhile Le Verrier sent a letter and urged Berlin Observatory astronomer Galle to search with the observatory s refractor 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 On the evening of 23 September 1846 the day Galle received the letter he discovered Neptune just northeast of Iota Aquarii 1 from the five degrees east of Delta Capricorn position Le Verrier had predicted it to be 41 42 about 12 from Adams s prediction and on the border of Aquarius and Capricornus according to the modern IAU constellation boundaries In the wake of the discovery there was a heated nationalistic rivalry between the French and the British over who deserved credit for the discovery Eventually an international consensus emerged that Le Verrier and Adams deserved joint credit Since 1966 Dennis Rawlins has questioned the credibility of Adams s claim to co discovery and the issue was re evaluated by historians with the return in 1998 of the Neptune papers historical documents to the Royal Observatory Greenwich 43 44 Naming Shortly after its discovery Neptune was referred to simply as the planet exterior to Uranus or as Le Verrier s planet The first suggestion for a name came from Galle who proposed the name Janus In England Challis put forward the name Oceanus 45 Claiming the right to name his discovery Le Verrier quickly proposed the name Neptune for this new planet though falsely stating that this had been officially approved by the French Bureau des Longitudes 46 In October he sought to name the planet Le Verrier after himself and he had loyal support in this from the observatory director Francois Arago This suggestion met with stiff resistance outside France 47 French almanacs quickly reintroduced the name Herschel for Uranus after that planet s discoverer Sir William Herschel and Leverrier for the new planet 48 Struve came out in favour of the name Neptune on 29 December 1846 to the Saint Petersburg Academy of Sciences 49 Soon Neptune became the internationally accepted name In Roman mythology Neptune was the god of the sea identified with the Greek Poseidon The demand for a mythological name seemed to be in keeping with the nomenclature of the other planets all of which were named for deities in Greek and Roman mythology e 50 Most languages today use some variant of the name Neptune for the planet indeed in Chinese Vietnamese Japanese and Korean the planet s name was translated as sea king star 海王星 51 52 In Mongolian Neptune is called Dalain van Dalajn van reflecting its namesake god s role as the ruler of the sea In modern Greek the planet is called Poseidon Poseidwnas Poseidonas the Greek counterpart of Neptune 53 In Hebrew Rahab רהב from a Biblical sea monster mentioned in the Book of Psalms was selected in a vote managed by the Academy of the Hebrew Language in 2009 as the official name for the planet even though the existing Latin term Neptun נפטון is commonly used 54 55 In Maori the planet is called Tangaroa named after the Maori god of the sea 56 In Nahuatl the planet is called Tlaloccitlalli named after the rain god Tlaloc 56 In Thai Neptune is referred to by its Westernised name Dao Nepchun Nepjun dawenpcun but is also called Dao Ket dawektu lit star of Ketu after Ketu क त the descending lunar node who plays a role in Hindu astrology In Malay the name Waruna after the Hindu god of seas is attested as far back as the 1970s 57 but was eventually superseded by the Latinate equivalents Neptun in Malaysian 58 or Neptunus in Indonesian 59 The usual adjectival form is Neptunian The nonce form Poseidean p e ˈ s aɪ d i en from Poseidon has also been used 4 though the usual adjectival form of Poseidon is Poseidonian ˌ p ɒ s aɪ ˈ d oʊ n i en 60 Status From its discovery in 1846 until the discovery of Pluto in 1930 Neptune was the farthest known planet When Pluto was discovered it was considered a planet and Neptune thus became the second farthest known planet except for a 20 year period between 1979 and 1999 when Pluto s elliptical orbit brought it closer than Neptune to the Sun making Neptune the ninth planet from the Sun during this period 61 62 The increasingly accurate estimations of Pluto s mass from ten times that of Earth s to far less than that of the Moon 63 and the discovery of the Kuiper belt in 1992 led many astronomers to debate whether Pluto should be considered a planet or as part of the Kuiper belt 64 65 In 2006 the International Astronomical Union defined the word planet for the first time reclassifying Pluto as a dwarf planet and making Neptune once again the outermost known planet in the Solar System 66 Physical characteristics nbsp A size comparison of Neptune and EarthNeptune s mass of 1 0243 1026 kg 7 is intermediate between Earth and the larger gas giants it is 17 times that of Earth but just 1 19th that of Jupiter f Its gravity at 1 bar is 11 15 m s2 1 14 times the surface gravity of Earth 67 and surpassed only by Jupiter 68 Neptune s equatorial radius of 24 764 km 10 is nearly four times that of Earth 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 69 In the search for exoplanets Neptune has been used as a metonym discovered bodies of similar mass are often referred to as Neptunes 70 just as scientists refer to various extrasolar bodies as Jupiters Internal structure See also Extraterrestrial diamonds Neptune s internal structure resembles that of Uranus Its atmosphere forms about 5 to 10 of its mass and extends perhaps 10 to 20 of the way towards the core Pressure in the atmosphere reaches about 10 GPa or about 100 000 times that of Earth s atmosphere Increasing concentrations of methane ammonia and water are found in the lower regions of the atmosphere 28 nbsp Physical and chemical composition of Neptune s interiorThe mantle is equivalent to 10 to 15 Earth masses and is rich in water ammonia and methane 1 As is customary in planetary science this mixture is referred to as icy even though it is a hot dense fluid supercritical fluid This fluid which has a high electrical conductivity is sometimes called a water ammonia ocean 71 The mantle may consist of a layer of ionic water in which the water molecules break down into a soup of hydrogen and oxygen ions and deeper down superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice 72 At a depth of 7 000 km the conditions may be such that methane decomposes into diamond crystals that rain downwards like hailstones 73 74 75 Scientists also believe that this kind of diamond rain occurs on Jupiter Saturn and Uranus 76 74 Very high pressure experiments at the Lawrence Livermore National Laboratory suggest that the top of the mantle may be an ocean of liquid carbon with floating solid diamonds 77 78 79 The core of Neptune is likely composed of iron nickel and silicates with an interior model giving a mass about 1 2 times that of Earth 80 The pressure at the centre is 7 Mbar 700 GPa about twice as high as that at the centre of Earth and the temperature may be 5 400 K 28 29 Atmosphere nbsp Combined colour and near infrared image of Neptune showing bands of methane in its atmosphere and four of its moons Proteus Larissa Galatea and Despina source source A time lapse video of Neptune and its moonsAt high altitudes Neptune s atmosphere is 80 hydrogen and 19 helium 28 A trace amount of methane is also present Prominent absorption bands of methane exist at wavelengths above 600 nm in the red and infrared portion of the spectrum As with Uranus this absorption of red light by atmospheric methane is part of what gives Neptune its blue hue 81 although Neptune s blue differs from Uranus s milder light blue nbsp Neptune cloud cover over three decades 1994 2023 82 Neptune s atmosphere is subdivided into two main regions the lower troposphere where temperature decreases with altitude and the stratosphere where temperature increases with altitude The boundary between the two the tropopause lies at a pressure of 0 1 bars 10 kPa 21 The stratosphere then gives way to the thermosphere at a pressure lower than 10 5 to 10 4 bars 1 to 10 Pa 21 The thermosphere gradually transitions to the exosphere nbsp Bands of high altitude clouds cast shadows on Neptune s lower cloud deck Models suggest that Neptune s troposphere is banded by clouds of varying compositions depending on altitude 82 The upper level clouds lie at pressures below one bar where the temperature is suitable for methane to condense For pressures between one and five bars 100 and 500 kPa clouds of ammonia and hydrogen sulfide are thought to form Above a pressure of five bars the clouds may consist of ammonia ammonium sulfide hydrogen sulfide and water Deeper clouds of water ice should be found at pressures of about 50 bars 5 0 MPa where the temperature reaches 273 K 0 C Underneath clouds of ammonia and hydrogen sulfide may be found 83 High altitude clouds on Neptune have been observed casting shadows on the opaque cloud deck below There are also high altitude cloud bands that wrap around the planet at constant latitudes These circumferential bands have widths of 50 150 km and lie about 50 110 km above the cloud deck 84 These altitudes are in the layer where weather occurs the troposphere Weather does not occur in the higher stratosphere or thermosphere In August 2023 the clouds of Neptune vanished possibly due to solar flare 82 Thirty years of observations by Hubble Space Telescope and ground based telescopes showed that Neptune s cloud activity is bound to Solar cycles and not to the planet s seasons 85 86 Neptune s spectra suggest that its lower stratosphere is hazy due to condensation of products of ultraviolet photolysis of methane such as ethane and ethyne 21 28 The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide 21 87 The stratosphere of Neptune is warmer than that of Uranus due to the elevated concentration of hydrocarbons 21 For reasons that remain obscure the planet s thermosphere is at an anomalously high temperature of about 750 K 88 89 The planet is too far from the Sun for this heat to be generated by ultraviolet radiation One candidate for a heating mechanism is atmospheric interaction with ions in the planet s magnetic field Other candidates are gravity waves from the interior that dissipate in the atmosphere The thermosphere contains traces of carbon dioxide and water which may have been deposited from external sources such as meteorites and dust 83 87 Magnetosphere Neptune resembles Uranus in its magnetosphere with a magnetic field strongly tilted relative to its rotational axis at 47 and offset at least 0 55 radius or about 13 500 km from the planet s physical centre Before Voyager 2 s arrival at Neptune it was hypothesised that Uranus s tilted magnetosphere was the result of its sideways rotation In comparing the magnetic fields of the two planets scientists now think the extreme orientation may be characteristic of flows in the planets interiors This field may be generated by convective fluid motions in a thin spherical shell of electrically conducting liquids probably a combination of ammonia methane and water 83 resulting in a dynamo action 90 The dipole component of the magnetic field at the magnetic equator of Neptune is about 14 microteslas 0 14 G 91 The dipole magnetic moment of Neptune is about 2 2 1017 T m3 14 mT RN3 where RN is the radius of Neptune Neptune s magnetic field has a complex geometry that includes relatively large contributions from non dipolar components including a strong quadrupole moment that may exceed the dipole moment in strength By contrast Earth Jupiter and Saturn have only relatively small quadrupole moments and their fields are less tilted from the polar axis The large quadrupole moment of Neptune may be the result of an offset from the planet s centre and geometrical constraints of the field s dynamo generator 92 93 Neptune s bow shock where the magnetosphere begins to slow the solar wind occurs at a distance of 34 9 times the radius of the planet The magnetopause where the pressure of the magnetosphere counterbalances the solar wind lies at a distance of 23 26 5 times the radius of Neptune The tail of the magnetosphere extends out to at least 72 times the radius of Neptune and likely much farther 92 Climate nbsp The Great Dark Spot top Scooter middle white cloud 94 and the Small Dark Spot bottom with contrast exaggerated Neptune s weather is characterised by extremely dynamic storm systems with winds reaching speeds of almost 600 m s 2 200 km h 1 300 mph exceeding supersonic flow 27 More typically by tracking the motion of persistent clouds wind speeds have been shown to vary from 20 m s in the easterly direction to 325 m s westward 95 At the cloud tops the prevailing winds range in speed from 400 m s along the equator to 250 m s at the poles 83 Most of the winds on Neptune move in a direction opposite the planet s rotation 96 The general pattern of winds showed prograde rotation at high latitudes vs retrograde rotation at lower latitudes The difference in flow direction is thought to be a skin effect and not due to any deeper atmospheric processes 21 At 70 S latitude a high speed jet travels at a speed of 300 m s 21 Neptune differs from Uranus in its typical level of meteorological activity Voyager 2 observed weather phenomena on Neptune during its 1989 flyby 97 but no comparable phenomena on Uranus during its 1986 fly by The abundance of methane ethane and acetylene at Neptune s equator is 10 100 times greater than at the poles This is interpreted as evidence for upwelling at the equator and subsidence near the poles because photochemistry cannot account for the distribution without meridional circulation 21 In 2007 it was discovered that the upper troposphere of Neptune s south pole was about 10 K warmer than the rest of its atmosphere which averages approximately 73 K 200 C The temperature differential is enough to let methane which elsewhere is frozen in the troposphere escape into the stratosphere near the pole 98 The relative hot spot is due to Neptune s axial tilt which has exposed the south pole to the Sun for the last quarter of Neptune s year or roughly 40 Earth years As Neptune slowly moves towards the opposite side of the Sun the south pole will be darkened and the north pole illuminated causing the methane release to shift to the north pole 99 Because of seasonal changes the cloud bands in the southern hemisphere of Neptune have been observed to increase in size and albedo This trend was first seen in 1980 The long orbital period of Neptune results in seasons lasting forty years 100 Storms In 1989 the Great Dark Spot an anticyclonic storm system spanning 13 000 km 6 600 km 8 100 mi 4 100 mi 97 was discovered by NASA s Voyager 2 spacecraft The storm resembled the Great Red Spot of Jupiter Some five years later 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 Neptune s northern hemisphere 101 The Scooter is another storm a white cloud group farther south than the Great Dark Spot This nickname first arose during the months leading up to the Voyager 2 encounter in 1989 when they were observed moving at speeds faster than the Great Dark Spot and images acquired later would subsequently reveal the presence of clouds moving even faster than those that had initially been detected by Voyager 2 96 The Small Dark Spot is a southern cyclonic storm the second most intense storm observed during the 1989 encounter It was initially completely dark but as Voyager 2 approached the planet a bright core developed and can be seen in most of the highest resolution images 102 More recently in 2018 a newer main dark spot and smaller dark spot were identified and studied 26 In 2023 the first ground based observation of a dark spot on Neptune was announced 103 Neptune s dark spots are thought to occur in the troposphere at lower altitudes than the brighter cloud features 104 so they appear as holes in the upper cloud decks As they are stable features that can persist for several months they are thought to be vortex structures 84 Often associated with dark spots are brighter persistent methane clouds that form around the tropopause layer 105 The persistence of companion clouds shows that some former dark spots may continue to exist as cyclones even though they are no longer visible as a dark feature Dark spots may dissipate when they migrate too close to the equator or possibly through some other unknown mechanism 106 nbsp The appearance of a Northern Great Dark Spot in 2018 is evidence of a huge storm brewing 107 nbsp The Northern Great Dark Spot and a smaller companion storm imaged by Hubble in 2020 108 nbsp The Great Dark Spot in a color uncalibrated image by Voyager 2 nbsp Neptune s shrinking vortex 109 Internal heating nbsp Four images taken a few hours apart with the NASA ESA Hubble Space Telescope s Wide Field Camera 3 Near infrared radiation data has been used as red channel 110 Neptune s more varied weather when compared to Uranus is due in part to its higher internal heating The upper regions of Neptune s troposphere reach a low temperature of 51 8 K 221 3 C At a depth where the atmospheric pressure equals 1 bar 100 kPa the temperature is 72 00 K 201 15 C 111 Deeper inside the layers of gas the temperature rises steadily As with Uranus the source of this heating is unknown but the discrepancy is larger Uranus only radiates 1 1 times as much energy as it receives from the Sun 112 whereas Neptune radiates about 2 61 times as much energy as it receives from the Sun 113 Neptune is the farthest planet from the Sun and lies over 50 farther from the Sun than Uranus and receives only 40 of its amount of sunlight 21 yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System Depending on the thermal properties of its interior the heat left over from Neptune s formation may be sufficient to explain its current heat flow though it is more difficult to simultaneously explain Uranus s lack of internal heat while preserving the apparent similarity between the two planets 114 Orbit and rotation nbsp Neptune red arc completes one orbit around the Sun centre for every 164 79 orbits of Earth The light blue object represents Uranus The average distance between Neptune and the Sun is 4 5 billion km about 30 1 astronomical units AU and it completes an orbit on average every 164 79 years subject to a variability of around 0 1 years The perihelion distance is 29 81 AU the aphelion distance is 30 33 AU g On 11 July 2011 Neptune completed its first full barycentric orbit since its discovery in 1846 116 although it did not appear at its exact discovery position in the sky because Earth was in a different location in its 365 26 day orbit Because of the motion of the Sun in relation to the barycentre of the Solar System on 11 July Neptune was also not at its exact discovery position in relation to the Sun if the more common heliocentric coordinate system is used the discovery longitude was reached on 12 July 2011 11 117 118 The elliptical orbit of Neptune is inclined 1 77 compared to that of Earth The axial tilt of Neptune is 28 32 119 which is similar to the tilts of Earth 23 and Mars 25 As a result Neptune experiences similar seasonal changes to Earth The long orbital period of Neptune means that the seasons last for forty Earth years 100 Its sidereal rotation period day is roughly 16 11 hours 11 Because its axial tilt is comparable to Earth s the variation in the length of its day over the course of its long year is not any more extreme Because Neptune is not a solid body its atmosphere undergoes differential rotation The wide equatorial zone rotates with a period of about 18 hours which is slower than the 16 1 hour rotation of the planet s magnetic field By contrast the reverse is true for the polar regions where the rotation period is 12 hours This differential rotation is the most pronounced of any planet in the Solar System 120 and it results in strong latitudinal wind shear 84 Orbital resonances Main articles Kuiper belt resonant trans Neptunian object and Neptune trojan nbsp A diagram showing the major orbital resonances in the Kuiper belt caused by Neptune the highlighted regions are the 2 3 resonance plutinos the nonresonant classical belt cubewanos and the 1 2 resonance twotinos Neptune s orbit has a profound impact on the region directly beyond it known as the Kuiper belt The Kuiper belt is a ring of small icy worlds similar to the asteroid belt but far larger extending from Neptune s orbit at 30 AU out to about 55 AU from the Sun 121 Much in the same way that Jupiter s gravity dominates the asteroid belt shaping its structure so Neptune s gravity dominates the Kuiper belt Over the age of the Solar System certain regions of the Kuiper belt became destabilised by Neptune s gravity creating gaps in its structure The region between 40 and 42 AU is an example 122 There do exist orbits within these empty regions where objects can survive for the age of the Solar System These resonances occur when Neptune s orbital period is a precise fraction of that of the object such as 1 2 or 3 4 If say an object orbits the Sun once for every two Neptune orbits it will only complete half an orbit by the time Neptune returns to its original position The most heavily populated resonance in the Kuiper belt with over 200 known objects 123 is the 2 3 resonance Objects in this resonance complete 2 orbits for every 3 of Neptune and are known as plutinos because the largest of the known Kuiper belt objects Pluto is among them 124 Although Pluto crosses Neptune s orbit regularly the 2 3 resonance ensures they can never collide 125 The 3 4 3 5 4 7 and 2 5 resonances are less populated 126 Neptune has a number of known trojan objects occupying both the Sun Neptune L4 and L5 Lagrangian points gravitationally stable regions leading and trailing Neptune in its orbit respectively 127 Neptune trojans can be viewed as being in a 1 1 resonance with Neptune Some Neptune trojans are remarkably stable in their orbits and are likely to have formed alongside Neptune rather than being captured The first object identified as associated with Neptune s trailing L5 Lagrangian point was 2008 LC18 128 Neptune also has a temporary quasi satellite 309239 2007 RW10 129 The object has been a quasi satellite of Neptune for about 12 500 years and it will remain in that dynamical state for another 12 500 years 129 Formation and migrationMain articles Formation and evolution of the Solar System and Nice model nbsp A simulation showing the outer planets and Kuiper belt a before Jupiter and Saturn reached a 2 1 resonance b after inward scattering of Kuiper belt objects following the orbital shift of Neptune c after ejection of scattered Kuiper belt bodies by JupiterThe formation of the ice giants Neptune and Uranus has proven difficult to model precisely Current models suggest that the matter density in the outer regions of the Solar System was too low to account for the formation of such large bodies from the traditionally accepted method of core accretion and various hypotheses have been advanced to explain their formation One is that the ice giants were not formed by core accretion but from instabilities within the original protoplanetary disc and later had their atmospheres blasted away by radiation from a nearby massive OB star 69 An alternative concept is that they formed closer to the Sun where the matter density was higher and then subsequently migrated to their current orbits after the removal of the gaseous protoplanetary disc 130 This hypothesis of migration after formation is favoured due to its ability to better explain the occupancy of the populations of small objects observed in the trans Neptunian region 131 The current most widely accepted 132 133 134 explanation of the details of this hypothesis is known as the Nice model which explores the effect of a migrating Neptune and the other giant planets on the structure of the Kuiper belt MoonsMain article Moons of Neptune For a timeline of discovery dates see Timeline of discovery of Solar System planets and their moons nbsp An annotated picture of Neptune s many moons as captured by the James Webb Space Telescope The bright blue diffraction star is Triton Neptune s largest moon Neptune has 14 known moons 7 135 Triton is the largest Neptunian moon comprising more than 99 5 of the mass in orbit around Neptune h and it is the only one massive enough to be spheroidal Triton was discovered by William Lassell just 17 days after the discovery of Neptune itself Unlike all other large planetary moons in the Solar System Triton has a retrograde orbit indicating that it was captured rather than forming in place it was probably once a dwarf planet in the Kuiper belt 136 It is close enough to Neptune to be locked into a synchronous rotation and it is slowly spiralling inward because of tidal acceleration It will eventually be torn apart in about 3 6 billion years when it reaches the Roche limit 137 In 1989 Triton was the coldest object that had yet been measured in the Solar System 138 with estimated temperatures of 38 K 235 C 139 Neptune s second known satellite by order of discovery the irregular moon Nereid has one of the most eccentric orbits of any satellite in the Solar System The eccentricity of 0 7512 gives it an apoapsis that is seven times its periapsis distance from Neptune i From July to September 1989 Voyager 2 discovered six moons of Neptune 140 Of these the irregularly shaped Proteus is notable for being as large as a body of its density can be without being pulled into a spherical shape by its own gravity 141 Although the second most massive Neptunian moon it is only 0 25 the mass of Triton Neptune s innermost four moons Naiad Thalassa Despina and Galatea orbit close enough to be within Neptune s rings The next farthest out Larissa was originally discovered in 1981 when it had occulted a star This occultation had been attributed to ring arcs but when Voyager 2 observed Neptune in 1989 Larissa was found to have caused it Five new irregular moons discovered between 2002 and 2003 were announced in 2004 142 143 A new moon and the smallest yet Hippocamp was found in 2013 by combining multiple Hubble images 144 Because Neptune was the Roman god of the sea Neptune s moons have been named after lesser sea gods 50 Planetary rings Main article Rings of Neptune nbsp Neptune s rings and moons viewed in infrared by the James Webb Space TelescopeNeptune has a planetary ring system though one much less substantial than that of Saturn 145 The rings may consist of ice particles coated with silicates or carbon based material which most likely gives them a reddish hue 146 The three main rings are the narrow Adams Ring 63 000 km from the centre of Neptune the Le Verrier Ring at 53 000 km and the broader fainter Galle Ring at 42 000 km A faint outward extension to the Le Verrier Ring has been named Lassell it is bounded at its outer edge by the Arago Ring at 57 000 km 147 The first of these planetary rings was detected in 1968 by a team led by Edward Guinan 30 148 In the early 1980s analysis of this data along with newer observations led to the hypothesis that this ring might be incomplete 149 Evidence that the rings might have gaps first arose during a stellar occultation in 1984 when the rings obscured a star on immersion but not on emersion 150 Images from Voyager 2 in 1989 settled the issue by showing several faint rings The outermost ring Adams contains five prominent arcs now named Courage Liberte Egalite 1 Egalite 2 and Fraternite Courage Liberty Equality and Fraternity 151 The existence of arcs was difficult to explain because the laws of motion would predict that arcs would spread out into a uniform ring over short timescales Astronomers now estimate that the arcs are corralled into their current form by the gravitational effects of Galatea a moon just inward from the ring 152 153 Earth based observations announced in 2005 appeared to show that Neptune s rings were much more unstable than previously thought Images taken from the W M Keck Observatory in 2002 and 2003 show considerable decay in the rings when compared to images by Voyager 2 In particular it seems that the Liberte arc might disappear in as little as one century 154 Observation nbsp Movement of Neptune in front of the stars of Aquarius in 2022 nbsp In 2018 the European Southern Observatory used adaptive optics to get clear and high resolution images of Neptune from the surface of Earth Neptune brightened about 10 between 1980 and 2000 mostly due to the changing of the seasons 155 Neptune may continue to brighten as it approaches perihelion in 2042 The apparent magnitude currently ranges from 7 67 to 7 89 with a mean of 7 78 and a standard deviation of 0 06 15 Prior to 1980 the planet was as faint as magnitude 8 0 15 Neptune is too faint to be visible to the naked eye It can be outshone by Jupiter s Galilean moons the dwarf planet Ceres and the asteroids 4 Vesta 2 Pallas 7 Iris 3 Juno and 6 Hebe 156 A telescope or strong binoculars will resolve Neptune as a small blue disk similar in appearance to Uranus 157 Because of the distance of Neptune from Earth its angular diameter only ranges from 2 2 to 2 4 arcseconds 7 17 the smallest of the Solar System planets Its small apparent size makes it challenging to study visually Most telescopic data was fairly limited until the advent of the Hubble Space Telescope and large ground based telescopes with adaptive optics AO 158 159 160 The first scientifically useful observation of Neptune from ground based telescopes using adaptive optics was commenced in 1997 from Hawaii 161 Neptune is currently approaching perihelion closest approach to the Sun and has been shown to be heating up with increased atmospheric activity and brightness as a consequence Combined with technological advancements ground based telescopes with adaptive optics are recording increasingly more detailed images of it Both Hubble and the adaptive optics telescopes on Earth have made many new discoveries within the Solar System since the mid 1990s with a large increase in the number of known satellites and moons around the outer planet among others In 2004 and 2005 five new small satellites of Neptune with diameters between 38 and 61 kilometres were discovered 162 From Earth Neptune goes through apparent retrograde motion every 367 days resulting in a looping motion against the background stars during each opposition These loops carried it close to the 1846 discovery coordinates in April and July 2010 and again in October and November 2011 118 Neptune s 164 year orbital period means that the planet takes an average of 13 years to move through each constellation of the zodiac In 2011 it completed its first full orbit of the Sun since being discovered and returned to where it was first spotted northeast of Iota Aquarii 41 Observation of Neptune in the radio frequency band shows that it is a source of both continuous emission and irregular bursts Both sources are thought to originate from its rotating magnetic field 83 In the infrared part of the spectrum Neptune s storms appear bright against the cooler background allowing the size and shape of these features to be readily tracked 163 ExplorationMain article Exploration of Neptune nbsp A Voyager 2 mosaic of TritonVoyager 2 is the only spacecraft that has visited Neptune The spacecraft s closest approach to the planet occurred on 25 August 1989 Because this was the last major planet the spacecraft could visit it was decided to make a close flyby of the moon Triton regardless of the consequences to the trajectory similarly to what was done for Voyager 1 s encounter with Saturn and its moon Titan The images relayed back to Earth from Voyager 2 became the basis of a 1989 PBS all night program Neptune All Night 164 During the encounter signals from the spacecraft required 246 minutes to reach Earth Hence for the most part Voyager 2 s mission relied on preloaded commands for the Neptune encounter The spacecraft performed a near encounter with the moon Nereid before it came within 4 400 km of Neptune s atmosphere on 25 August then passed close to the planet s largest moon Triton later the same day 165 The spacecraft verified the existence of a magnetic field surrounding the planet and discovered that the field was offset from the centre and tilted in a manner similar to the field around Uranus Neptune s rotation period was determined using measurements of radio emissions and Voyager 2 also showed that Neptune had a surprisingly active weather system Six new moons were discovered and the planet was shown to have more than one ring 140 165 The flyby also provided the first accurate measurement of Neptune s mass which was found to be 0 5 percent less than previously calculated The new figure disproved the hypothesis that an undiscovered Planet X acted upon the orbits of Neptune and Uranus 166 167 Since 2018 the China National Space Administration has been studying a concept for a pair of Voyager like interstellar probes tentatively known as Interstellar Express or Interstellar Heliosphere Probe 168 Both probes will be launched at the same time in 2024 and take differing paths to explore opposing ends of the heliosphere the second probe IHP 2 will fly by Neptune in January 2038 passing only 1 000 km above the cloud tops and potentially carry an atmospheric impactor to be released during its approach 169 Afterward it will continue on its mission throughout the Kuiper belt toward the tail of the heliosphere so far unexplored After Voyager 2 and IHP 2 s flybys the next step in scientific exploration of the Neptunian system is considered to be an orbital mission most proposals have been by NASA most often for a Flagship orbiter 170 Such a hypothetical mission is envisioned to be possible in the late 2020s or early 2030s 170 However there have been discussions to launch Neptune missions sooner In 2003 there was a proposal in NASA s Vision Missions Studies for a Neptune Orbiter with Probes mission that does Cassini level science 171 Another more recent proposal was for Argo a flyby spacecraft to be launched in 2019 that would visit Jupiter Saturn Neptune and a Kuiper belt object The focus would be on Neptune and its largest moon Triton to be investigated around 2029 172 The proposed New Horizons 2 mission which was later scrapped might also have done a close flyby of the Neptunian system Currently a pending proposal for the Discovery program Trident would conduct a flyby of Neptune and Triton 173 however the mission was not selected for Discovery 15 or 16 Neptune Odyssey is the current mission concept for a Neptune orbiter and atmospheric probe being studied as a possible large strategic science mission by NASA that would launch between 2031 and 2033 and arrive at Neptune by 2049 174 See alsoOutline of Neptune Hot Neptune Neptune in astrology Neptunium Neptune the Mystic one of the seven movements in Gustav Holst s Planets suite Timeline of the far future Stats of planets in the Solar SystemNotes Orbital elements refer to the Neptune barycentre and Solar System barycentre These are the instantaneous osculating values at the precise J2000 epoch Barycentre quantities are given because in contrast to the planetary centre they do not experience appreciable changes on a day to day basis from the motion of the moons a b c d e f g Refers to the level of 1 bar 100 kPa atmospheric pressure Based on the volume within the level of 1 bar atmospheric pressure A second symbol an LV monogram nbsp for Le Verrier analogous to the H monogram nbsp for Uranus It was never much used outside of France and is now archaic One might be tempted to say except Earth which in the English language is the name of a Germanic deity Erda The IAU policy is that one may call the Earth and the Moon by any name commonly used in the language being used Contrary to common use by science fiction writers Terra and Luna are not the official names of planet Earth and its moon See the wikipedia article Earth for references The mass of Earth is 5 9736 1024 kg giving a mass ratio M Neptune M Earth 1 02 10 26 5 97 10 24 17 09 displaystyle tfrac M text Neptune M text Earth tfrac 1 02 times 10 26 5 97 times 10 24 17 09 nbsp The mass of Uranus is 8 6810 1025 kg giving a mass ratio M Uranus M Earth 8 68 10 25 5 97 10 24 14 54 displaystyle tfrac M text Uranus M text Earth tfrac 8 68 times 10 25 5 97 times 10 24 14 54 nbsp The mass of Jupiter is 1 8986 1027 kg giving a mass ratio M Jupiter M Neptune 1 90 10 27 1 02 10 26 18 63 displaystyle tfrac M text Jupiter M text Neptune tfrac 1 90 times 10 27 1 02 times 10 26 18 63 nbsp Mass values from Williams David R 29 November 2007 Planetary Fact Sheet Metric NASA Archived from the original on 5 September 2014 Retrieved 13 March 2008 The last three aphelia were 30 33 AU the next is 30 34 AU The perihelia are even more stable at 29 81 AU 115 Mass of Triton 2 14 1022 kg Combined mass of 12 other known moons of Neptune 7 53 1019 kg or 0 35 The mass of the rings is negligible r a r p 2 1 e 1 2 0 2488 1 7 039 displaystyle tfrac r a r p tfrac 2 1 e 1 2 0 2488 1 approx 7 039 nbsp References a b c Hamilton Calvin J 4 August 2001 Neptune Views of the Solar System Archived from the original on 15 July 2007 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 Online ed Oxford University Press Subscription or participating institution membership required a b Enabling Exploration with Small Radioisotope Power Systems PDF NASA September 2004 Archived from the original PDF on 22 December 2016 Retrieved 26 January 2016 Yeomans Donald K HORIZONS Web Interface for Neptune Barycenter Major Body 8 JPL Horizons On Line Ephemeris System Archived from the original on 7 September 2021 Retrieved 18 July 2014 Select Ephemeris Type Orbital Elements Time Span 2000 01 01 12 00 to 2000 01 02 Target Body Neptune Barycenter and Center Solar System Barycenter 0 a b Seligman Courtney Rotation Period and Day Length Archived from the original on 28 July 2011 Retrieved 13 August 2009 a b c d e f g h i j k l m n o p 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 amp Astrophysics 543 11 Bibcode 2012A amp A 543A 133S doi 10 1051 0004 6361 201219011 A133 HORIZONS Planet center Batch call for September 2042 Perihelion ssd jpl nasa gov Perihelion for Neptune s planet center 899 occurs on 2042 Sep 04 at 29 80647406au during a rdot flip from negative to positive NASA JPL Archived from the original on 7 September 2021 Retrieved 7 September 2021 a b c d e f Seidelmann P Kenneth Archinal Brent A A Hearn Michael F Conrad Albert R Consolmagno Guy J Hestroffer Daniel et al 2007 Report of the IAU IAG Working Group on cartographic coordinates and rotational elements 2006 Celestial Mechanics and Dynamical Astronomy 98 3 155 180 Bibcode 2007CeMDA 98 155S doi 10 1007 s10569 007 9072 y a b c Munsell K Smith H Harvey S 13 November 2007 Neptune Facts amp Figures NASA Archived from the original on 9 April 2014 Retrieved 14 August 2007 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 Pearl J C et al 1991 The albedo effective temperature and energy balance of Neptune as determined from Voyager data Journal of Geophysical Research 96 18 921 930 Bibcode 1991JGR 9618921P doi 10 1029 91JA01087 Mallama Anthony Krobusek Bruce Pavlov Hristo 2017 Comprehensive wide band magnitudes and albedos for the planets with applications to exo planets and Planet Nine Icarus 282 19 33 arXiv 1609 05048 Bibcode 2017Icar 282 19M doi 10 1016 j icarus 2016 09 023 S2CID 119307693 a b c d 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 amp C 25 10M doi 10 1016 j ascom 2018 08 002 S2CID 69912809 Encyclopedia the brightest bodies IMCCE Retrieved 29 May 2023 a b Espenak Fred 20 July 2005 Twelve Year Planetary Ephemeris 1995 2006 NASA Archived from the original on 5 December 2012 Retrieved 1 March 2008 Chang Kenneth 18 October 2014 Dark Spots in Our Knowledge of Neptune The New York Times Archived from the original on 28 October 2014 Retrieved 21 October 2014 Exploration Neptune NASA Solar System Exploration Archived from the original on 17 July 2020 Retrieved 3 February 2020 In 1989 NASA s Voyager 2 became the first and only spacecraft to study Neptune up close Podolak M Weizman A Marley M December 1995 Comparative models of Uranus and Neptune Planetary and Space Science 43 12 1517 1522 Bibcode 1995P amp SS 43 1517P doi 10 1016 0032 0633 95 00061 5 a b c d e f g h i j Lunine Jonathan I September 1993 The atmospheres of Uranus and Neptune Annual Review of Astronomy and Astrophysics 31 217 263 Bibcode 1993ARA amp A 31 217L doi 10 1146 annurev aa 31 090193 001245 Munsell Kirk Smith Harman Harvey Samantha 13 November 2007 Neptune overview Solar System Exploration NASA Archived from the original on 3 March 2008 Retrieved 20 February 2008 info noirlab edu Gemini North Telescope Helps Explain Why Uranus and Neptune Are Different Colors Observations from Gemini Observatory a Program of NSF s NOIRLab and other telescopes reveal that excess haze on Uranus makes it paler than Neptune www noirlab edu Retrieved 30 July 2022 Laboratory By NSF s NOIRLab National Optical Infrared Astronomy Research Why Uranus and Neptune Are Different Colors NASA Solar System Exploration Retrieved 6 March 2023 Magazine Smithsonian Kuta Sarah Why Neptune Appears Bluer Than Its Cousin Uranus Smithsonian Magazine Retrieved 30 July 2022 a b Shannon Stirone 22 December 2020 Neptune s Weird Dark Spot Just Got Weirder While observing the planet s large inky storm astronomers spotted a smaller vortex they named Dark Spot Jr The New York Times Archived from the original on 22 December 2020 Retrieved 22 December 2020 a b Suomi V E Limaye S S Johnson D R 1991 High Winds of Neptune A possible mechanism Science 251 4996 929 32 Bibcode 1991Sci 251 929S doi 10 1126 science 251 4996 929 PMID 17847386 S2CID 46419483 a b c d e Hubbard W B 1997 Neptune s Deep Chemistry Science 275 5304 1279 80 doi 10 1126 science 275 5304 1279 PMID 9064785 S2CID 36248590 a b Nettelmann N French M Holst B Redmer R Interior Models of Jupiter Saturn and Neptune PDF University of Rostock Archived from the original PDF on 18 July 2011 Retrieved 25 February 2008 a b Wilford John N 10 June 1982 Data Shows 2 Rings Circling Neptune The New York Times Archived from the original on 10 December 2008 Retrieved 29 February 2008 Hirschfeld Alan 2001 Parallax The Race to Measure the Cosmos New York New York Henry Holt ISBN 978 0 8050 7133 7 Littmann Mark Standish E M 2004 Planets Beyond Discovering the Outer Solar System Courier Dover Publications ISBN 978 0 486 43602 9 Britt Robert Roy 2009 Galileo discovered Neptune new theory claims NBC News News Archived from the original on 4 November 2013 Retrieved 10 July 2009 Bouvard A 1821 Tables astronomiques publiees par le Bureau des Longitudes de France Paris Bachelier a b c Airy G B 13 November 1846 Account of some circumstances historically connected with the discovery of the planet exterior to Uranus Monthly Notices of the Royal Astronomical Society 7 10 121 44 Bibcode 1846MNRAS 7 121A doi 10 1002 asna 18470251002 Archived from the original on 29 September 2021 Retrieved 12 June 2019 O Connor John J Robertson Edmund F 2006 John Couch Adams account of the discovery of Neptune University of St Andrews Archived from the original on 26 January 2008 Retrieved 18 February 2008 Adams J C 13 November 1846 Explanation of the observed irregularities in the motion of Uranus on the hypothesis of disturbance by a more distant planet Monthly Notices of the Royal Astronomical Society 7 9 149 52 Bibcode 1846MNRAS 7 149A doi 10 1093 mnras 7 9 149 Archived PDF from the original on 2 May 2019 Retrieved 25 August 2019 Challis Rev J 13 November 1846 Account of observations at the Cambridge observatory for detecting the planet exterior to Uranus Monthly Notices of the Royal Astronomical Society 7 9 145 149 Bibcode 1846MNRAS 7 145C doi 10 1093 mnras 7 9 145 Archived PDF from the original on 4 May 2019 Retrieved 25 August 2019 Sack Harald 12 December 2017 James Challis and his failure to discover the planet Neptune scihi org Retrieved 15 November 2021 Galle J G 13 November 1846 Account of the discovery of the planet of Le Verrier at Berlin Monthly Notices of the Royal Astronomical Society 7 9 153 Bibcode 1846MNRAS 7 153G doi 10 1093 mnras 7 9 153 a b Gaherty Geoff 12 July 2011 Neptune Completes First Orbit Since Its Discovery in 1846 space com Archived from the original on 25 August 2019 Retrieved 3 September 2019 Levenson Thomas 2015 The Hunt for Vulcan and how Albert Einstein Destroyed a Planet Discovered Relativity and Deciphered the Universe Random House p 38 Kollerstrom Nick 2001 Neptune s Discovery The British Case for Co Prediction University College London Archived from the original on 11 November 2005 Retrieved 19 March 2007 William Sheehan Nicholas Kollerstrom Craig B Waff December 2004 The case of the pilfered planet did the British steal Neptune Scientific American Archived from the original on 19 March 2011 Retrieved 20 January 2011 Moore 2000 206 Littmann Mark 2004 Planets Beyond Exploring the Outer Solar System Courier Dover Publications p 50 ISBN 978 0 486 43602 9 Baum Richard Sheehan William 2003 In Search of Planet Vulcan The ghost in Newton s clockwork universe Basic Books pp 109 10 ISBN 978 0 7382 0889 3 Gingerich Owen October 1958 The naming of Uranus and Neptune Astronomical Society of the Pacific Leaflets 8 352 9 15 Bibcode 1958ASPL 8 9G Hind J R 1847 Second report of proceedings in the Cambridge Observatory relating to the new Planet Neptune Astronomische Nachrichten 25 21 309 14 Bibcode 1847AN 25 309 doi 10 1002 asna 18470252102 Archived from the original on 29 September 2021 Retrieved 12 June 2019 a b Planet and Satellite Names and Discoverers Gazetteer of Planetary Nomenclature U S Geological Survey 17 December 2008 Archived from the original on 9 August 2018 Retrieved 26 March 2012 Planetary linguistics nineplanets org Archived from the original on 7 April 2010 Retrieved 8 April 2010 Sao Hải Vương Cục băng khổng lồ xa tit tắp in Vietnamese Kenh14 31 October 2010 Archived from the original on 30 July 2018 Retrieved 30 July 2018 Greek Names of the Planets 25 April 2010 Archived from the original on 9 May 2010 Retrieved 14 July 2012 Neptune or Poseidon as is its Greek name was the God of the Seas It is the eight planet from the sun Ettinger Yair 31 December 2009 Uranus and Neptune get Hebrew names at last Haaretz Archived from the original on 25 June 2018 Retrieved 16 August 2018 Belizovsky Avi 31 December 2009 אוראנוס הוא מהיום אורון ונפטון מעתה רהב Uranus is now Oron and Neptune is now Rahav Hayadan in Hebrew Archived from the original on 24 June 2018 Retrieved 16 August 2018 a b Appendix 5 Planetary Linguistics Archived 19 April 2010 at the Wayback Machine Nineplanets org Mohamed Kadir 1975 Waruna Kamus Kebangsaan Ejaan Baru Inggeris bahasa Malaysia Bahasa Malaysia Inggeris Titiwangsa pp 299 857 Archived from the original on 29 September 2021 Retrieved 29 May 2021 Neptun Kamus Dewan 4th ed Dewan Bahasa dan Pustaka Malaysia 2017 Archived from the original on 7 May 2021 Retrieved 5 May 2021 Neptunus Kamus Besar Bahasa Indonesia 3rd ed Badan Pengembangan dan Pembinaan Bahasa Indonesia 2016 Archived from the original on 29 September 2021 Retrieved 5 May 2021 The Century Dictionary 1914 Long Tony 21 January 2008 Jan 21 1979 Neptune Moves Outside Pluto s Wacky Orbit Wired Archived from the original on 27 March 2008 Retrieved 13 March 2008 Space com Staff 17 November 2006 Neptune Data Sheet Space com Stern Alan Tholen David James 1997 Pluto and Charon University of Arizona Press pp 206 208 ISBN 978 0 8165 1840 1 Weissman Paul R 1995 The Kuiper Belt Annual Review of Astronomy and Astrophysics 33 327 57 Bibcode 1995ARA amp A 33 327W doi 10 1146 annurev aa 33 090195 001551 The Status of Pluto A clarification International Astronomical Union Press release 1999 Archived from the original on 15 June 2006 Retrieved 25 May 2006 IAU 2006 General Assembly Resolutions 5 and 6 PDF IAU 24 August 2006 Archived PDF from the original on 25 June 2008 Retrieved 22 July 2008 Neptune Fact Sheet NASA Archived from the original on 1 July 2010 Retrieved 22 September 2005 Unsold Albrecht Baschek Bodo 2001 The New Cosmos An introduction to astronomy and astrophysics 5th ed Springer Table 3 1 page 47 Bibcode 2001ncia book U ISBN 978 3 540 67877 9 a b Boss Alan P 2002 Formation of gas and ice giant planets Earth and Planetary Science Letters 202 3 4 513 23 Bibcode 2002E amp PSL 202 513B doi 10 1016 S0012 821X 02 00808 7 Lovis C Mayor M Alibert Y Benz W 18 May 2006 Trio of Neptunes and their Belt ESO Archived from the original on 13 January 2010 Retrieved 25 February 2008 Atreya S Egeler P Baines K 2006 Water ammonia ionic ocean on Uranus and Neptune PDF Geophysical Research Abstracts 8 05179 Archived PDF from the original on 5 February 2012 Retrieved 7 November 2007 Shiga David 1 September 2010 Weird water lurking inside giant planets New Scientist No 2776 Archived from the original on 12 February 2018 Retrieved 11 February 2018 Kerr Richard A October 1999 Neptune May Crush Methane into Diamonds Science 286 5437 25a 25 doi 10 1126 science 286 5437 25a PMID 10532884 S2CID 42814647 a b Kaplan Sarah 25 August 2017 It rains solid diamonds on Uranus and Neptune The Washington Post Archived from the original on 27 August 2017 Retrieved 27 August 2017 Kraus D et al September 2017 Formation of diamonds in laser compressed hydrocarbons at planetary interior conditions Nature Astronomy 1 9 606 11 Bibcode 2017NatAs 1 606K doi 10 1038 s41550 017 0219 9 S2CID 46945778 Archived from the original on 23 October 2018 Retrieved 25 August 2018 Sean Kane 29 April 2016 Lightning storms make it rain diamonds on Saturn and Jupiter Business Insider Archived from the original on 26 June 2019 Retrieved 22 May 2019 Baldwin Emily 21 January 2010 Oceans of diamond possible on Uranus and Neptune Astronomy Now Archived from the original on 3 December 2013 Bradley D K Eggert J H Hicks D G Celliers P M 30 July 2004 Shock Compressing Diamond to a Conducting Fluid PDF Physical Review Letters 93 19 195506 Bibcode 2004PhRvL 93s5506B doi 10 1103 physrevlett 93 195506 hdl 1959 3 380076 PMID 15600850 S2CID 6203103 Archived from the original PDF on 21 December 2016 Retrieved 16 March 2016 Eggert J H Hicks D G Celliers P M Bradley D K et al 8 November 2009 Melting temperature of diamond at ultrahigh pressure Nature Physics 6 40 40 43 Bibcode 2010NatPh 6 40E doi 10 1038 nphys1438 Podolak M Weizman A Marley M 1995 Comparative models of Uranus and Neptune Planetary and Space Science 43 12 1517 22 Bibcode 1995P amp SS 43 1517P doi 10 1016 0032 0633 95 00061 5 Crisp D Hammel H B 14 June 1995 Hubble Space Telescope Observations of Neptune Hubble News Center Archived from the original on 2 August 2007 Retrieved 22 April 2007 a b c Andrews Robin George 18 August 2023 Neptune s Clouds Have Vanished and Scientists Think They Know Why A recent study suggests a relationship between solar cycles and the atmosphere of the solar system s eighth planet The New York Times Archived from the original on 18 August 2023 Retrieved 21 August 2023 a b c d e Elkins Tanton Linda T 2006 Uranus Neptune Pluto and the Outer Solar System New York Chelsea House pp 79 83 ISBN 978 0 8160 5197 7 a b c Max C E Macintosh B A Gibbard S G Gavel D T et al 2003 Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics The Astronomical Journal 125 1 364 75 Bibcode 2003AJ 125 364M doi 10 1086 344943 Gianopoulos Andrea 16 August 2023 Neptune s Disappearing Clouds Linked to the Solar Cycle NASA Retrieved 24 August 2023 Chavez Erandi de Pater Imke Redwing Erin Molter Edward M Roman Michael T Zorzi Andrea Alvarez Carlos Campbell Randy de Kleer Katherine Hueso Ricardo Wong Michael H Gates Elinor Lynam Paul David Davies Ashley G Aycock Joel Mcilroy Jason Pelletier John Ridenour Anthony Stickel Terry 1 November 2023 Evolution of Neptune at near infrared wavelengths from 1994 through 2022 Icarus 404 115667 arXiv 2307 08157 Bibcode 2023Icar 40415667C doi 10 1016 j icarus 2023 115667 ISSN 0019 1035 S2CID 259515455 Retrieved 24 August 2023 The clear positive correlation we find between cloud activity and Solar Lyman Alpha 121 56 nm irradiance lends support to the theory that the periodicity in Neptune s cloud activity results from photochemical cloud haze production triggered by Solar ultraviolet emissions a b Encrenaz Therese February 2003 ISO observations of the giant planets and Titan What have we learnt Planetary and Space Science 51 2 89 103 Bibcode 2003P amp SS 51 89E doi 10 1016 S0032 0633 02 00145 9 Broadfoot A L Atreya S K Bertaux J L et al 1999 Ultraviolet Spectrometer Observations of Neptune and Triton PDF Science 246 4936 1459 66 Bibcode 1989Sci 246 1459B doi 10 1126 science 246 4936 1459 PMID 17756000 S2CID 21809358 Archived PDF from the original on 28 May 2008 Retrieved 12 March 2008 Herbert Floyd Sandel Bill R August September 1999 Ultraviolet observations of Uranus and Neptune Planetary and Space Science 47 8 9 1 119 139 Bibcode 1999P amp SS 47 1119H doi 10 1016 S0032 0633 98 00142 1 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 53 Bibcode 2004Natur 428 151S doi 10 1038 nature02376 PMID 15014493 S2CID 33352017 Connerney J E P Acuna Mario H Ness Norman F 1991 The magnetic field of Neptune Journal of Geophysical Research 96 19 023 42 Bibcode 1991JGR 9619023C doi 10 1029 91JA01165 a b Ness N F Acuna M H Burlaga L F Connerney J E P Lepping R P Neubauer F M 1989 Magnetic Fields at Neptune Science 246 4936 1473 78 Bibcode 1989Sci 246 1473N doi 10 1126 science 246 4936 1473 PMID 17756002 S2CID 20274953 Archived PDF from the original on 10 July 2019 Retrieved 25 August 2019 Russell C T Luhmann J G 1997 Neptune Magnetic Field and Magnetosphere University of California Los Angeles Archived from the original on 29 June 2019 Retrieved 10 August 2006 Lavoie Sue 8 January 1998 PIA01142 Neptune Scooter NASA Archived from the original on 29 October 2013 Retrieved 26 March 2006 Hammel H B Beebe R F De Jong E M Hansen C J et al 1989 Neptune s wind speeds obtained by tracking clouds in Voyager 2 images Science 24 4924 1367 69 Bibcode 1989Sci 245 1367H doi 10 1126 science 245 4924 1367 PMID 17798743 S2CID 206573894 a b Burgess 1991 64 70 a b Lavoie Sue 16 February 2000 PIA02245 Neptune s blue green atmosphere NASA JPL Archived from the original on 5 August 2013 Retrieved 28 February 2008 Orton G S Encrenaz T Leyrat C Puetter R et al 2007 Evidence for methane escape and strong seasonal and dynamical perturbations of Neptune s atmospheric temperatures Astronomy and Astrophysics 473 1 L5 L8 Bibcode 2007A amp A 473L 5O doi 10 1051 0004 6361 20078277 S2CID 54996279 Orton Glenn Encrenaz Therese 18 September 2007 A Warm South Pole Yes On Neptune ESO Archived from the original on 23 March 2010 Retrieved 20 September 2007 a b Villard Ray Devitt Terry 15 May 2003 Brighter Neptune Suggests A Planetary Change of Seasons Hubble News Center Retrieved 26 February 2008 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 42 Bibcode 1995Sci 268 1740H doi 10 1126 science 268 5218 1740 PMID 17834994 S2CID 11688794 Lavoie Sue 29 January 1996 PIA00064 Neptune s Dark Spot D2 at High Resolution NASA JPL Archived from the original on 27 September 2013 Retrieved 28 February 2008 information eso org Mysterious Neptune dark spot detected from Earth for the first time www eso org Retrieved 26 August 2023 S G Gibbard de Pater I Roe H G Martin S et al 2003 The altitude of Neptune cloud features from high spatial resolution near infrared spectra PDF Icarus 166 2 359 74 Bibcode 2003Icar 166 359G doi 10 1016 j icarus 2003 07 006 Archived from the original PDF on 20 February 2012 Retrieved 26 February 2008 Stratman P W Showman A P Dowling T E Sromovsky L A 2001 EPIC Simulations of Bright Companions to Neptune s Great Dark Spots PDF Icarus 151 2 275 85 Bibcode 1998Icar 132 239L doi 10 1006 icar 1998 5918 Archived PDF from the original on 27 February 2008 Retrieved 26 February 2008 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 Bibcode 2000DPS 32 0903S A storm is coming spacetelescope org Archived from the original on 20 February 2019 Retrieved 19 February 2019 Michael H Wong Amy Simon 15 December 2020 Dark Storm on Neptune Reverses Direction Possibly Shedding Fragment Hubblesite Archived from the original on 25 December 2020 Retrieved 25 December 2020 Neptune s shrinking vortex spacetelescope org Archived from the original on 19 February 2018 Retrieved 19 February 2018 Happy birthday Neptune ESA Hubble Archived from the original on 15 July 2011 Retrieved 13 July 2011 Lindal Gunnar F 1992 The atmosphere of Neptune an analysis of radio occultation data acquired with Voyager 2 Astronomical Journal 103 967 82 Bibcode 1992AJ 103 967L doi 10 1086 116119 Class 12 Giant Planets Heat and Formation 3750 Planets Moons amp Rings Colorado University Boulder 2004 Archived from the original on 21 June 2008 Retrieved 13 March 2008 Pearl J C Conrath B J 1991 The albedo effective temperature and energy balance of Neptune as determined from Voyager data Journal of Geophysical Research Space Physics 96 18 921 30 Bibcode 1991JGR 9618921P doi 10 1029 91ja01087 Imke de Pater and Jack J Lissauer 2001 Planetary Sciences Archived 29 September 2021 at the Wayback Machine 1st edition p 224 Meeus Jean 1998 Astronomical Algorithms Richmond VA Willmann Bell p 273 Supplemented by further use of VSOP87 McKie Robin 9 July 2011 Neptune s first orbit a turning point in astronomy The Guardian Archived from the original on 23 August 2016 Retrieved 15 December 2016 Nancy Atkinson 26 August 2010 Clearing the Confusion on Neptune s Orbit Universe Today Archived from the original on 27 July 2011 Retrieved 10 July 2011 Bill Folkner at JPL Archived 29 September 2021 at the Wayback Machine a b Anonymous 16 November 2007 Horizons Output for Neptune 2010 2011 Archived from the original on 2 May 2013 Retrieved 25 February 2008 Numbers generated using the Solar System Dynamics Group Horizons On Line Ephemeris System Williams David R 6 January 2005 Planetary Fact Sheets NASA Archived from the original on 25 September 2008 Retrieved 28 February 2008 Hubbard W B Nellis W J Mitchell A C Holmes N C et al 1991 Interior Structure of Neptune Comparison with Uranus Science 253 5020 648 51 Bibcode 1991Sci 253 648H doi 10 1126 science 253 5020 648 PMID 17772369 S2CID 20752830 Archived from the original on 23 October 2018 Retrieved 12 June 2019 Stern S Alan Colwell Joshua E 1997 Collisional Erosion in the Primordial Edgeworth Kuiper Belt and the Generation of the 30 50 AU Kuiper Gap The Astrophysical Journal 490 2 879 82 Bibcode 1997ApJ 490 879S doi 10 1086 304912 Petit Jean Marc Morbidelli Alessandro Valsecchi Giovanni B 1999 Large Scattered Planetesimals and the Excitation of the Small Body Belts PDF Icarus 141 2 367 87 Bibcode 1999Icar 141 367P doi 10 1006 icar 1999 6166 Archived from the original PDF on 1 December 2007 Retrieved 23 June 2007 List of Transneptunian Objects Minor Planet Center Archived from the original on 27 October 2010 Retrieved 25 October 2010 Jewitt David 2004 The Plutinos UCLA Archived from the original on 19 April 2007 Retrieved 28 February 2008 Varadi F 1999 Periodic Orbits in the 3 2 Orbital Resonance and Their Stability The Astronomical Journal 118 5 2526 31 Bibcode 1999AJ 118 2526V doi 10 1086 301088 John Davies 2001 Beyond Pluto Exploring the outer limits of the solar system Cambridge University Press p 104 ISBN 978 0 521 80019 8 Chiang E I Jordan A B Millis R L M W Buie et al 2003 Resonance Occupation in the Kuiper Belt Case Examples of the 5 2 and Trojan Resonances The Astronomical Journal 126 1 430 43 arXiv astro ph 0301458 Bibcode 2003AJ 126 430C doi 10 1086 375207 S2CID 54079935 Sheppard Scott S Trujillo Chadwick A 10 September 2010 Detection of a Trailing L5 Neptune Trojan Science 329 5997 1304 Bibcode 2010Sci 329 1304S doi 10 1126 science 1189666 PMID 20705814 S2CID 7657932 a b De La Fuente Marcos C amp De La Fuente Marcos R 2012 309239 2007 RW10 a large temporary quasi satellite of Neptune Astronomy and Astrophysics Letters 545 2012 L9 arXiv 1209 1577 Bibcode 2012A amp A 545L 9D doi 10 1051 0004 6361 201219931 S2CID 118374080 Thommes Edward W Duncan Martin J Levison Harold F 2002 The formation of Uranus and Neptune among Jupiter and Saturn The Astronomical Journal 123 5 2862 83 arXiv astro ph 0111290 Bibcode 2002AJ 123 2862T doi 10 1086 339975 S2CID 17510705 Hansen Kathryn 7 June 2005 Orbital shuffle for early solar system Geotimes Archived from the original on 27 September 2007 Retrieved 26 August 2007 Crida A 2009 Solar System Formation Reviews in Modern Astronomy Vol 21 p 3008 arXiv 0903 3008 Bibcode 2009RvMA 21 215C doi 10 1002 9783527629190 ch12 ISBN 978 3 527 62919 0 Desch S J 2007 Mass Distribution and Planet Formation in the Solar Nebula PDF The Astrophysical Journal 671 1 878 93 Bibcode 2007ApJ 671 878D doi 10 1086 522825 S2CID 120903003 Archived from the original PDF on 7 February 2020 Smith R L J Churcher M C Wyatt M M Moerchen et al 2009 Resolved debris disc emission around h Telescopii a young solar system or ongoing planet formation Astronomy and Astrophysics 493 1 299 308 arXiv 0810 5087 Bibcode 2009A amp A 493 299S doi 10 1051 0004 6361 200810706 S2CID 6588381 Hubble Space Telescope discovers fourteenth tiny moon orbiting Neptune Space Military and Medicine Archived 16 July 2013 at the Wayback Machine News com au 16 July 2013 Retrieved on 28 July 2013 Agnor Craig B Hamilton Douglas P 2006 Neptune s capture of its moon Triton in a binary planet gravitational encounter Nature 441 7090 192 94 Bibcode 2006Natur 441 192A doi 10 1038 nature04792 PMID 16688170 S2CID 4420518 Chyba Christopher F Jankowski D G Nicholson P D 1989 Tidal evolution in the Neptune Triton system Astronomy and Astrophysics 219 1 2 L23 L26 Bibcode 1989A amp A 219L 23C Wilford John N 29 August 1989 Triton May Be Coldest Spot in Solar System The New York Times Archived from the original on 10 December 2008 Retrieved 29 February 2008 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 Bibcode 1990Sci 250 429N doi 10 1126 science 250 4979 429 PMID 17793020 S2CID 20022185 a b Stone E C Miner E D 1989 The Voyager 2 Encounter with the Neptunian System Science 246 4936 1417 21 Bibcode 1989Sci 246 1417S doi 10 1126 science 246 4936 1417 PMID 17755996 S2CID 9367553 Brown Michael E The Dwarf Planets California Institute of Technology Department of Geological Sciences Archived from the original on 19 July 2011 Retrieved 9 February 2008 Holman M J Kavelaars J J Grav T et al 2004 Discovery of five irregular moons of Neptune PDF Nature 430 7002 865 67 Bibcode 2004Natur 430 865H doi 10 1038 nature02832 PMID 15318214 S2CID 4412380 Archived PDF from the original on 2 November 2013 Retrieved 24 October 2011 Five new moons for planet Neptune BBC News 18 August 2004 Archived from the original on 8 August 2007 Retrieved 6 August 2007 Grush Loren 20 February 2019 Neptune s newly discovered moon may be the survivor of an ancient collision The Verge Archived from the original on 21 February 2019 Retrieved 22 February 2019 O Callaghan Jonathan 21 September 2022 Neptune and Its Rings Come Into Focus With Webb Telescope New images from the space based observatory offer a novel view of the planet in infrared The New York Times Retrieved 23 September 2022 Cruikshank Dale P 1996 Neptune and Triton University of Arizona Press pp 703 804 ISBN 978 0 8165 1525 7 Blue Jennifer 8 December 2004 Nomenclature Ring and Ring Gap Nomenclature Gazetteer of Planetary Nomenclature USGS Archived from the original on 5 July 2010 Retrieved 28 February 2008 Guinan E F Harris C C Maloney F P 1982 Evidence for a Ring System of Neptune Bulletin of the American Astronomical Society 14 658 Bibcode 1982BAAS 14 658G Goldreich P Tremaine S Borderies N E F 1986 Towards a theory for Neptune s arc rings PDF Astronomical Journal 92 490 94 Bibcode 1986AJ 92 490G doi 10 1086 114178 Archived PDF from the original on 29 September 2021 Retrieved 12 June 2019 Nicholson P D et al 1990 Five Stellar Occultations by Neptune Further Observations of Ring Arcs Icarus 87 1 1 39 Bibcode 1990Icar 87 1N doi 10 1016 0019 1035 90 90020 A Cox Arthur N 2001 Allen s Astrophysical Quantities Springer ISBN 978 0 387 98746 0 Munsell Kirk Smith Harman Harvey Samantha 13 November 2007 Planets Neptune Rings Solar System Exploration NASA Archived from the original on 4 July 2012 Retrieved 29 February 2008 Salo Heikki Hanninen Jyrki 1998 Neptune s Partial Rings Action of Galatea on Self Gravitating Arc Particles Science 282 5391 1102 04 Bibcode 1998Sci 282 1102S doi 10 1126 science 282 5391 1102 PMID 9804544 Neptune s rings are fading away New Scientist 26 March 2005 Archived from the original on 10 December 2008 Retrieved 6 August 2007 Schmude R W Jr Baker R E Fox J Krobusek B A Pavlov H Mallama A 29 March 2016 The secular and rotational brightness variations of Neptune unpublished manuscript arXiv 1604 00518 a href Template Cite report html title Template Cite report cite report a CS1 maint multiple names authors list link See the respective articles for magnitude data Moore 2000 207 In 1977 for example even the rotation period of Neptune remained uncertain Cruikshank D P 1 March 1978 On the rotation period of Neptune Astrophysical Journal Letters 220 L57 L59 Bibcode 1978ApJ 220L 57C doi 10 1086 182636 Max C MacIntosh B Gibbard S Roe H et al 1999 Adaptive Optics Imaging of Neptune and Titan with the W M Keck Telescope Bulletin of the American Astronomical Society 31 1512 Bibcode 1999AAS 195 9302M Nemiroff R Bonnell J eds 18 February 2000 Neptune through Adaptive Optics Astronomy Picture of the Day NASA First Ground Based Adaptive Optics Observations of Neptune and Proteus Archived 19 September 2017 at the Wayback Machine Planetary amp Space Science Vol 45 No 8 pp 1031 36 1997 Uranus and Neptune Reports on Astronomy 2003 2005 pp 147f Gibbard S G Roe H de Pater I Macintosh B et al 1999 High Resolution Infrared Imaging of Neptune from the Keck Telescope Icarus 156 1 1 15 Bibcode 2002Icar 156 1G doi 10 1006 icar 2001 6766 Archived from the original on 23 October 2018 Retrieved 12 June 2019 Phillips Cynthia 5 August 2003 Fascination with Distant Worlds SETI Institute Archived from the original on 3 November 2007 Retrieved 3 October 2007 a b Burgess 1991 46 55 Tom Standage 2000 The Neptune File A Story of Astronomical Rivalry and the Pioneers of Planet Hunting New York Walker p 188 ISBN 978 0 8027 1363 6 Chris Gebhardt Jeff Goldader 20 August 2011 Thirty four years after launch Voyager 2 continues to explore NASASpaceflight Archived from the original on 19 February 2016 Retrieved 22 January 2016 Wu Weiren Yu Dengyun Huang Jiangchuan Zong Qiugang Wang Chi Yu Guobin He Rongwei Wang Qian Kang Yan Meng Linzhi Wu Ke He Jiansen Li Hui 9 January 2019 Exploring the solar system boundary Scientia Sinica Informationis 49 1 1 doi 10 1360 N112018 00273 ISSN 2095 9486 Jones Andrew 16 April 2021 China to launch a pair of spacecraft towards the edge of the solar system SpaceNews Archived from the original on 15 May 2021 Retrieved 29 April 2021 a b Clark Stephen 25 August 2015 Uranus Neptune in NASA s sights for new robotic mission Spaceflight Now Archived from the original on 6 September 2015 Retrieved 7 September 2015 Spilker T R Ingersoll A P 2004 Outstanding Science in the Neptune System From an Aerocaptured Vision Mission Bulletin of the American Astronomical Society 36 1094 Bibcode 2004DPS 36 1412S Candice Hansen et al Argo A Voyage Through the Outer Solar System PDF SpacePolicyOnline com Space and Technology Policy Group LLC Archived from the original PDF on 24 September 2015 Retrieved 5 August 2015 Exploring Triton With Trident A Discovery Class Mission PDF Universities Space Research Association 23 March 2019 Archived PDF from the original on 2 August 2020 Retrieved 26 March 2019 Abigail Rymer Brenda Clyde Kirby Runyon August 2020 Neptune Odyssey Mission to the Neptune Triton System PDF Archived PDF from the original on 15 December 2020 Retrieved 18 April 2021 BibliographyBurgess Eric 1991 Far Encounter The Neptune system Columbia University Press ISBN 978 0 231 07412 4 Moore Patrick 2000 The Data Book of Astronomy CRC Press ISBN 978 0 7503 0620 1 Further readingMiner Ellis D Wessen Randii R 2002 Neptune The Planet Rings and Satellites Springer Verlag ISBN 978 1 85233 216 7 Standage Tom 2001 The Neptune File Penguin ISBN 978 0 8027 1363 6 External links nbsp Wikimedia Commons has media related to Neptune planet NASA s Neptune fact sheet Neptune from Bill Arnett s nineplanets org Neptune Astronomy Cast episode No 63 includes full transcript Neptune Profile archived 15 November 2002 at NASA s Solar System Exploration site Interactive 3D gravity simulation of Neptune and its inner moons Archived 22 September 2020 at the Wayback Machine Portals nbsp Astronomy nbsp Solar system nbsp Stars nbsp Spaceflight nbsp Outer space Retrieved from https en wikipedia org w index php title Neptune amp oldid 1175839895, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.