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90377 Sedna
Single fuzzy white dot with lots of background noise
Low-resolution image of Sedna by the Hubble Space Telescope, March 2004
Discovered byMichael Brown
Chad Trujillo
David Rabinowitz
Discovery date14 November 2003
(90377) Sedna
Named after
Sedna (Inuit goddess of sea and marine animals)
2003 VB12
TNO[2] · detached
sednoid[3] dwarf planet
Symbol⯲ (mostly astrological)
Orbital characteristics[2]
Epoch 31 May 2020 (JD 2458900.5)
Uncertainty parameter 2
Observation arc30 years
Earliest precovery date25 September 1990
Aphelion937 AU (140 billion km)[5][a]
Perihelion76.19 AU (11.4 billion km)[6][5][7]
506 AU (76 billion km)[5] or 0.007 ly
11390 yr (barycentric)[a]
11,408 Gregorian years
1.04 km/s
0° 0m 0.289s / day
≈ 18 July 2076[6][7]
Physical characteristics
> 1025±135 km
(occultation chord)[9]
10.273±0.002 h
(~18 h less likely)[10]
Temperature≈ 12 K (see note)
(red) B−V=1.24; V−R=0.78[11]
20.8 (opposition)[12]
20.5 (perihelic)[13]

Sedna (minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun beyond the orbit of Neptune. Discovered in 2003, the planetoid's surface is one of the reddest known among Solar System bodies. Spectroscopy has revealed Sedna's surface to be mostly a mixture of the solid ices of water, methane, and nitrogen, along with widespread deposits of reddish-colored tholins, a chemical makeup similar to those of some other trans-Neptunian objects. Within the range of uncertainties, it is tied with the dwarf planet Ceres in the asteroid belt as the largest dwarf planet not known to have a moon. Its diameter is roughly 1,000 km (most likely in between those of Ceres and Saturn's moon Tethys). Owing to its lack of known moons, the Keplerian laws of planetary motion cannot be employed for determining its mass, and the precise figure as yet remains unknown.

Sedna's orbit is one of the widest known in the Solar System. Its aphelion, or its farthest point from the Sun in its elliptical orbit, is located 937 astronomical units (AU) away.[5] This is some 31 times the distance of Neptune's aphelion, and 19 times that of Pluto, sending most of its highly elongated orbit well beyond the heliopause, the boundary beyond which the influence of particles from interstellar space dominates over that of the Sun. Sedna's orbit is also one of the most narrow and elliptical discovered, with an eccentricity of 0.8496. This means that its perihelion, or point of closest approach to the Sun, at 76 AU is around 12.3 times closer than its aphelion. At perihelion, Sedna is only 55% further than Pluto's aphelion. As of January 2024, Sedna is near perihelion, 83.55 AU (12.50 billion km) from the Sun,[15] and 2.8 times farther away than Neptune. The dwarf planets Eris and Gonggong are presently farther away from the Sun than Sedna. It is suggested that an exploratory fly-by mission to Sedna near its perihelion through a Jupiter gravity assist could be completed in 24.5 years.[16]

Due to its exceptionally elongated orbit, the dwarf planet takes approximately 11,400 years, over 11 millennia, to return to the same point in its orbit around the Sun. The IAU initially considered Sedna to be a member of the scattered disc, a group of objects sent into high-eccentricity orbits by the gravitational influence of Neptune. Several astronomers who worked in the associated field contested this classification, however, as even its perihelion is far too distant for it to have been scattered by any of the currently known planets. This has led some astronomers to informally refer to it as the first known member of the inner Oort cloud. The dwarf planet is also the prototype of a new orbital class of objects named after itself, the sednoids, which include 2012 VP113, Leleākūhonua, and 2021 RR205, all celestial bodies with extremely elongated orbits.

The astronomer Michael E. Brown, co-discoverer of Sedna, believes that studying Sedna's unusual orbit could yield valuable information on the origin and early evolution of the Solar System.[17][18] It might have been perturbed into its orbit by one or more stars within the Sun's birth cluster, or captured from a nearby wandering star, or to have been sent into its present orbit through a close gravitational encounter with the hypothetical 9th planet, some time during the solar system's formation. The statistically unusual clustering to one side of the solar system of the aphelions of Sedna and other similar objects is speculated to be the evidence for the existence of a planet beyond the orbit of Neptune, which would by itself orbit on the opposing side of the Sun.[19][20][21]



Sedna (provisionally designated 2003 VB12) was discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory), and David Rabinowitz (Yale University) on 14 November 2003. The discovery formed part of a survey begun in 2001 with the Samuel Oschin telescope at Palomar Observatory near San Diego, California, using Yale's 160-megapixel Palomar Quest camera. On that day, an object was observed to move by 4.6 arcseconds over 3.1 hours relative to stars, which indicated that its distance was about 100 AU. Follow-up observations were made in November–December 2003 with the SMARTS (Small and Medium Research Telescope System) at Cerro Tololo Inter-American Observatory in Chile, the Tenagra IV telescope in Nogales, Arizona, and the Keck Observatory on Mauna Kea in Hawaii. Combined with precovery observations taken at the Samuel Oschin telescope in August 2003, and by the Near-Earth Asteroid Tracking consortium in 2001–2002, these observations allowed the accurate determination of its orbit. The calculations showed that the object was moving along a distant and highly eccentric orbit, at a distance of 90.3 AU from the Sun.[22][19] Precovery images have since been found in the Palomar Digitized Sky Survey dating back to 25 September 1990.[2]


Brown initially nicknamed Sedna "The Flying Dutchman", or "Dutch", after a legendary ghost ship, because its slow movement had initially masked its presence from his team.[23] He eventually settled on the official name after the goddess Sedna from Inuit mythology, partly because he mistakenly thought the Inuit were the closest polar culture to his home in Pasadena, and partly because the name, unlike Quaoar, would be easily pronounceable by English speakers.[23] Brown further justified his choice of naming by stating that the goddess Sedna's traditional location at the bottom of the Arctic Ocean reflected Sedna's large distance from the Sun.[24] He suggested to the International Astronomical Union's (IAU) Minor Planet Center that any objects discovered in Sedna's orbital region in the future should be named after mythical entities in Arctic mythologies.[24]

The team made the name "Sedna" public before the object had been officially numbered, which caused some controversy among the community of amateur astronomers.[25] Brian Marsden, the head of the Minor Planet Center, stated that such an action was a violation of protocol, and that some members of the IAU might vote against it.[26] Despite the complaints, no objection was raised to the name, and no competing names were suggested. The IAU's Committee on Small Body Nomenclature accepted the name in September 2004,[27] and considered that, in similar cases of extraordinary interest, it might in the future allow names to be announced before they were officially numbered.[25]

Sedna has no symbol in the astronomical literature, as planetary symbols are no longer much used in astronomy. Unicode includes a symbol ⯲ (U+2BF2),[28] but this is mostly used among astrologers.[29] The symbol is a monogram of Inuktitut: ᓴᓐᓇ Sanna, the modern pronunciation of Sedna's name.[29]

Orbit and rotation[edit]

A large oval represents the orbit of Sedna around the offset Sun and smaller, more circular planetary orbits
The orbit of Sedna set against the orbits of outer Solar System objects (top and side views, Pluto's orbit is purple, Neptune's is blue)
A grid chart showing smoothly varying brightness over time
The 10,000 year apparent magnitudes of Sedna and two other sednoids

Sedna has the longest orbital period of any known object in the Solar System of its size or larger with an orbital period of around 11,400 years.[5][a] Its orbit is extremely eccentric, with an aphelion of approximately 937 AU[5] and a perihelion of 76.19 AU. Near aphelion, Sedna is one of the coldest places in the Solar System, located far past the termination shock, where temperatures never exceed −240°C (−400°F) due to its extreme distance.[32][33] At aphelion, Sun as viewed from Sedna is a particularly bright star in the otherwise black sky, being about 45% as bright as the full moon as seen from Earth.[34] Its perihelion was the largest for any known Solar System object until the discovery of the sednoid 2012 VP113.[35][36] At its aphelion, Sedna orbits the Sun at a meagre 377 m/s,[37] 1.3% that of Earth's average orbital speed.[38]

When Sedna was first discovered, it was 89.6 AU[39] away from the Sun, approaching perihelion, and was the most distant object in the Solar System observed. Sedna was later surpassed by Eris, which was detected by the same survey near its aphelion at 97 AU. Because Sedna is near perihelion as of 2024, both Eris and Gonggong are farther from the Sun, at 96 AU and 89 AU respectively, than Sedna at 84 AU, despite both of their semi-major axes being shorter than Sedna's.[40][41][12] The orbits of some long-period comets extend further than that of Sedna; they are too dim to be discovered except when approaching perihelion in the inner Solar System. As Sedna nears its perihelion in mid-2076,[6][b] the Sun will appear merely as a very bright pinpoint in its sky, the G-type star too far away to be visible as a disc to the naked eye.[42]

When first discovered, Sedna was thought to have an unusually long rotational period (20 to 50 days).[43] It was initially speculated that Sedna's rotation was slowed by the gravitational pull of a large binary companion, similar to Pluto's moon Charon.[24] However, a search for such a satellite by the Hubble Space Telescope in March 2004 found no such objects.[43][c] Subsequent measurements from the MMT telescope showed that Sedna in reality has a much shorter rotation period of about 10 hours, more typical for a body its size. It could rotate in about 18 hours instead, but this is thought to be unlikely.[10]

Physical characteristics[edit]

Sedna is a spherical shape at lower left with a crescent glow from the distant Sun at upper right
Artist's visualization of Sedna. Sedna has a reddish hue.

Sedna has a V band absolute magnitude of about 1.8, and is estimated to have an albedo (reflectivity) of around 0.41, giving it a diameter of approximately 900 km.[14] At the time of discovery it was the brightest object found in the Solar System since Pluto in 1930. In 2004, the discoverers placed an upper limit of 1,800 km on its diameter;[45] after observations by the Spitzer Space Telescope, this was revised downward by 2007 to less than 1,600 km.[46] In 2012, measurements from the Herschel Space Observatory suggested that Sedna's diameter was 995 ± 80 km, which would make it smaller than Pluto's moon Charon.[14] In 2013, the same team re-analyzed Sedna's thermal data with an improved thermophysical model and found a consistent value of 906+314
, suggesting that the original model fit was too precise.[8] Australian observations of a stellar occultation by Sedna in 2013 produced similar results on its diameter, giving chord lengths 1025±135 km and 1305±565 km.[9] The size of this object suggests it could have undergone differentiation and may have a sub-surface liquid ocean and possibly geologic activity.[47]

As Sedna has no known moons, the direct determination of its mass is as yet impossible without either sending a space probe, or perhaps locating a nearby object which is gravitationally perturbed by the planetoid. It is the largest trans-Neptunian Sun-orbiting object not known to have a natural satellite.[48] Observations from the Hubble Space Telescope in 2004 were the only published attempt to find a satellite,[49][50] and it is possible that a satellite could have been lost in the glare from Sedna itself.[51]

Observations from the SMARTS telescope show that Sedna, in visible light, is one of the reddest objects known in the Solar System, nearly as red as Mars.[24] Its deep red spectral slope is indicative of high concentrations of organic material on its surface.[47] Chad Trujillo and his colleagues suggest that Sedna's dark red color is caused by an extensive surface coating of hydrocarbon sludge, termed tholins. Tholins are a reddish-colored, amorphous, and heterogeneous organic mixture hypothesized to have been transmuted from simpler organic compounds, following billions of years of continuous exposure to ultraviolet radiation, interstellar particles, and other harsh environs as the dwarf planet either comes close to the Sun or transits interstellar space.[52] Its surface is homogeneous in color and spectrum; this may be because Sedna, unlike objects nearer the Sun, is rarely impacted by other bodies, which would expose bright patches of fresh icy material like that on 8405 Asbolus.[52] Sedna and two other very distant objects – 2006 SQ372 and (87269) 2000 OO67 – share their color with outer classical Kuiper belt objects and the centaur 5145 Pholus, suggesting a similar region of origin.[53]

Trujillo and colleagues have placed upper limits on Sedna's surface composition of 60% for methane ice and 70% for water ice.[52] The presence of methane further supports the existence of tholins on Sedna's surface, as methane is among the organic compounds capable of giving rise to tholins.[47] Barucci and colleagues compared Sedna's spectrum with that of Triton and detected weak absorption bands belonging to methane and nitrogen ices. From these observations, they suggested the following model of the surface: 24% Triton-type tholins, 7% amorphous carbon, 10% nitrogen ices, 26% methanol, and 33% methane.[54] The detection of methane and water ices was confirmed in 2006 by the Spitzer Space Telescope mid-infrared photometry.[47] The European Southern Observatory's Very Large Telescope observed Sedna with the SINFONI near-infrared spectrometer, finding indications of tholins and water ice on the surface.[55]

In 2022, low resolution near-infrared (0.7–5 μm) spectroscopic observations by the James Webb Space Telescope (JWST) revealed the presence of significant amounts of ethane ice (C2H6) and of complex organics on the surface of Sedna. The JWST spectra also contain evidence of presence of small amounts of ethylene (C2H4), acetylene (C2H2) and possibly carbon dioxide (CO2). On the other hand little evidence of presence of methane (CH4) and nitrogen ices was found at variance with the earlier observations.[56]

The possible presence of nitrogen on the surface suggests that, at least for a short time, Sedna may have a tenuous atmosphere. During a 200-year period near perihelion, the maximum temperature on Sedna should exceed 35.6 K (−237.6 °C), the transition temperature between alpha-phase solid N2 and the beta-phase seen on Triton. At 38 K, the N2 vapor pressure would be 14 microbar (1.4 Pa). The weak methane absorption bands indicate that methane on Sedna's surface is ancient, as opposed to being freshly deposited. This finding indicates that Sedna's surface never reaches a temperature high enough for methane on the surface to evaporate and subsequently fall back as snow, which happens on Triton and probably on Pluto.[47]


In their paper announcing the discovery of Sedna, Brown and his colleagues described it as the first observed body belonging to the Oort cloud, the hypothetical cloud of comets thought to exist out to nearly a light-year from the Sun. They observed that, unlike scattered disc objects such as Eris, Sedna's perihelion (76 AU) is too distant for it to have been scattered by the gravitational influence of Neptune.[19] Because it is considerably closer to the Sun than was expected for an Oort cloud object, and has an inclination roughly in line with the planets and the Kuiper belt, they described the planetoid as being an "inner Oort cloud object", situated in the disc reaching from the Kuiper belt to the spherical part of the cloud.[57][58]

If Sedna formed in its current location, the Sun's original protoplanetary disc must have extended as far as 75 AU into space.[59] Also, Sedna's initial orbit must have been approximately circular, otherwise its formation by the accretion of smaller bodies into a whole would not have been possible, because the large relative velocities between planetesimals would have been too disruptive. Therefore, it must have been tugged into its current eccentric orbit by a gravitational interaction with another body.[60] In their initial paper, Brown, Rabinowitz and colleagues suggested three possible candidates for the perturbing body: an unseen planet beyond the Kuiper belt, a single passing star, or one of the young stars embedded with the Sun in the stellar cluster in which it formed.[19]

Brown and his team favored the hypothesis that Sedna was lifted into its current orbit by a star from the Sun's birth cluster, arguing that Sedna's aphelion of about 1,000 AU, which is relatively close compared to those of long-period comets, is not distant enough to be affected by passing stars at their current distances from the Sun. They propose that Sedna's orbit is best explained by the Sun having formed in an open cluster of several stars that gradually disassociated over time.[19][61][62] That hypothesis has also been advanced by both Alessandro Morbidelli and Scott Jay Kenyon.[63][64] Computer simulations by Julio A. Fernandez and Adrian Brunini suggest that multiple close passes by young stars in such a cluster would pull many objects into Sedna-like orbits.[19] A study by Morbidelli and Levison suggested that the most likely explanation for Sedna's orbit was that it had been perturbed by a close (approximately 800 AU) pass by another star in the first 100 million years or so of the Solar System's existence.[63][65]

EarthMoonCharonCharonNixNixKerberosKerberosStyxStyxHydraHydraPlutoPlutoDysnomiaDysnomiaErisErisNamakaNamakaHi'iakaHi'iakaHaumeaHaumeaMakemakeMakemakeMK2MK2XiangliuXiangliuGonggongGonggongWeywotWeywotQuaoarQuaoarSednaSednaVanthVanthOrcusOrcusActaeaActaeaSalaciaSalacia2002 MS42002 MS4File:10 Largest Trans-Neptunian objects (TNOS).png
Artistic comparison of Pluto, Eris, Makemake, Haumea, Gonggong (2007 OR10), Sedna, Quaoar, Orcus, 2002 MS4, and Salacia.

The trans-Neptunian planet hypothesis has been advanced in several forms by a number of astronomers, including Rodney Gomes and Patryk Lykawka. One scenario involves perturbations of Sedna's orbit by a hypothetical planetary-sized body in the inner Oort cloud. In 2006, simulations suggested that Sedna's orbital traits could be explained by perturbations of a Jupiter-mass (MJ) object at 5,000 AU (or less), a Neptune-mass object at 2,000 AU, or even an Earth-mass object at 1,000 AU.[62][66] Computer simulations by Patryk Lykawka have indicated that Sedna's orbit may have been caused by a body roughly the size of Earth, ejected outward by Neptune early in the Solar System's formation and currently in an elongated orbit between 80 and 170 AU from the Sun.[67] Brown's various sky surveys have not detected any Earth-sized objects out to a distance of about 100 AU. It is possible that such an object may have been scattered out of the Solar System after the formation of the inner Oort cloud.[68]

Caltech researchers Konstantin Batygin and Brown have hypothesized the existence of a super-Earth planet in the outer Solar System, Planet Nine, to explain the orbits of a group of extreme trans-Neptunian objects that includes Sedna.[21][69] This planet would be perhaps six times as massive as Earth.[70] It would have a highly eccentric orbit, and its average distance from the Sun would be about 15 times that of Neptune (which orbits at an average distance of 30.1 astronomical units (4.50×109 km)). Accordingly, its orbital period would be approximately 7,000 to 15,000 years.[70]

Morbidelli and Kenyon have suggested that Sedna did not originate in the Solar System, but was captured by the Sun from a passing extrasolar planetary system, specifically that of a brown dwarf about 1/20th the mass of the Sun (M)[63][64][71] or a main-sequence star 80 percent more massive than the Sun, which, owing to its larger mass, may now be a white dwarf. In either case, the stellar encounter had likely occurred within 100 million years after the Sun's formation.[63][72][73] Stellar encounters during this time would have minimal effect on the Oort cloud's final mass and population since the Sun had excess material for replenishing the Oort cloud.[63]


Three overlapping ovals represent the orbits
Orbit diagram of Sedna, 2012 VP113, and Leleākūhonua with 100 AU grids for scale

Sedna's highly elliptical orbit, and thus a narrow temporal window for detection and observation with currently available technology, means that the probability of its detection was roughly 1 in 80. Unless its discovery were a fluke, it is expected that another 40–120 Sedna-sized objects with roughly the same orbital parameters would exist in the outer solar system.[19][44]

In 2007, astronomer Megan Schwamb outlined how each of the proposed mechanisms for Sedna's extreme orbit would affect the structure and dynamics of any wider population. If a trans-Neptunian planet was responsible, all such objects would share roughly the same perihelion (about 80 AU). If Sedna was captured from another planetary system that rotated in the same direction as the Solar System, then all of its population would have orbits on relatively low inclinations and have semi-major axes ranging from 100 to 500 AU. If it rotated in the opposite direction, then two populations would form, one with low and one with high inclinations. The perturbations from passing stars would produce a wide variety of perihelia and inclinations, each dependent on the number and angle of such encounters.[68]

A larger sample of objects with Sedna's extreme perihelion may help in determining which scenario is most likely.[74] "I call Sedna a fossil record of the earliest Solar System", said Brown in 2006. "Eventually, when other fossil records are found, Sedna will help tell us how the Sun formed and the number of stars that were close to the Sun when it formed."[17] A 2007–2008 survey by Brown, Rabinowitz and Megan Schwamb attempted to locate another member of Sedna's hypothetical population. Although the survey was sensitive to movement out to 1,000 AU and discovered the likely dwarf planet Gonggong, it detected no new sednoid.[74] Subsequent simulations incorporating the new data suggested about 40 Sedna-sized objects probably exist in this region, with the brightest being about Eris's magnitude (−1.0).[74]

In 2014, Chad Trujillo and Scott Sheppard announced the discovery of 2012 VP113,[36] an object half the size of Sedna, a 4,200-year orbit similar to Sedna's, and a perihelion within Sedna's range of roughly 80 AU;[75] they speculated that this similarity of orbits may be due to the gravitational shepherding effect of a trans-Neptunian planet.[76] Another high-perihelion trans-Neptunian object was announced by Sheppard and colleagues in 2018, provisionally designated 2015 TG387 and now named Leleākūhonua.[77] With a perihelion of 65 AU and an even more distant orbit with a period of 40,000 years, its longitude of perihelion (the location where it makes its closest approach to the Sun) appears to be aligned with the directions of both Sedna and 2012 VP113, strengthening the case for an apparent orbital clustering of trans-Neptunian objects suspected to be influenced by a hypothetical distant planet, dubbed Planet Nine. In a study detailing Sedna's population and Leleākūhonua's orbital dynamics, Sheppard concluded that the discovery implies a population of about 2 million inner Oort Cloud objects larger than 40 km, with a total mass in the range of 1×1022 kg (several times the mass of the asteroid belt and 80% the mass of Pluto).[78]

Sedna was recovered from Transiting Exoplanet Survey Satellite data in 2020, as part of preliminary work for an all-sky survey searching for Planet Nine and other as-yet-unknown trans-Neptunian objects.[79]


The discovery of Sedna renewed the old question of just which astronomical objects ought to be considered planets, and which ones ought not be. On 15 March 2004, articles on Sedna in the popular press reported misleadingly that a tenth planet had been discovered. This question was resolved for many astronomers by applying the International Astronomical Union's definition of a planet, adopted on 24 August 2006, which mandated that a planet must have cleared the neighborhood around its orbit. Sedna is not expected to have cleared its neighborhood; quantitatively speaking, its Stern–Levison parameter is estimated to be much less than 1.[d] The IAU also adopted dwarf planet as a term for the largest non-planets (despite the name) that, like planets, are in hydrostatic equilibrium and thus can display planet-like geological activity, yet have not cleared their orbital neighborhoods.[81] Sedna is bright enough, and therefore large enough, that it is expected to be in hydrostatic equilibrium.[82] Hence, astronomers generally consider Sedna a dwarf planet.[55][83][84][85][86][87]

Beside its physical classification, Sedna is also categorized according to its orbit. The Minor Planet Center, which officially catalogs the objects in the Solar System, designates Sedna only as a trans-Neptunian object (as it orbits beyond Neptune),[88] as does the JPL Small-Body Database.[89] The question of a more precise orbital classification has been much debated, and many astronomers have suggested that the sednoids, together with similar objects such as 2000 CR105, be placed in a new category of distant objects named extended scattered disc objects (E-SDO),[90] detached objects,[91] distant detached objects (DDO),[66] or scattered-extended in the formal classification by the Deep Ecliptic Survey.[92]


Sedna will come to perihelion around July 2076.[6][b] This close approach to the Sun provides a window of opportunity for studying it that will not occur again for more than 11 thousand years. Because Sedna spends much of its orbit beyond the heliopause, the point at which the solar wind gives way to the interstellar particle wind, examining Sedna's surface would provide unique information on the effects of interstellar radiation, as well as the properties of the solar wind at its farthest extent.[93] It was calculated in 2011 that a flyby mission to Sedna could take 24.48 years using a Jupiter gravity assist, based on launch dates of 6 May 2033 or 23 June 2046. Sedna would be either 77.27 or 76.43 AU from the Sun when the spacecraft arrives near the end of 2057 or 2070, respectively.[16] Other potential flight trajectories involve gravity assists from Venus, Earth, Saturn, and Neptune as well as Jupiter.[94] Research at the University of Tennessee has also examined the potential for a lander.[95]


  1. ^ a b c Given the orbital eccentricity of this object, different epochs can generate quite different heliocentric unperturbed two-body best-fit solutions to the orbital period. Using a 1990 epoch, Sedna has a 12,100-year period,[3] but using a 2019 epoch Sedna has a 10,500-year period.[30] For objects at such high eccentricity, the Solar System's barycenter (Sun+Jupiter) generates solutions that are more stable than heliocentric solutions.[31] Using JPL Horizons, the barycentric orbital period is consistently about 11,388 years, with a variation of 2 years over the next two centuries.[5]
  2. ^ a b Different programs using different epochs and/or data sets will produce slightly different dates for Sedna's perihelion as they generate instantaneous unperturbed 2-body solutions. Using a 2020 epoch, the JPL Small-Body Database has a perihelion date of 9 March 2076.[2] Using a 1990 epoch the Lowell DES has perihelion on 2479285.9863 (14 December 2075). As of 2021, the JPL Horizons (using much more accurate numerical integration) indicates a perihelion date of 18 July 2076.[6]
  3. ^ The HST search found no satellite candidates to a limit of about 500 times fainter than Sedna (Brown and Suer 2007).[44]
  4. ^ The Stern–Levison parameter (Λ) as defined by Alan Stern and Harold F. Levison in 2002 determines if an object will eventually clear its orbital neighbourhood of small bodies. It is defined as the object's fraction of solar mass (i.e. the object's mass divided by the Sun's mass) squared, divided by its semi-major axis to the 3/2 power, times a constant 1.7×1016.[80](see equation 4) If an object's Λ is greater than 1, then that object will eventually clear its neighbourhood, and it can be considered for planethood. Using the unlikely highest estimated mass for Sedna of 2×1021 kg, Sedna's Λ is (2×1021/1.9891×1030)2 / 5193/2 × 1.7×1016 = 1.44×10−6. This is much less than 1, so Sedna is not a planet by this criterion.


  1. ^ "Discovery Circumstances: Numbered Minor Planets (90001)–(95000)". IAU: Minor Planet Center. Archived from the original on 9 November 2017. Retrieved 23 July 2008.
  2. ^ a b c d e "JPL Small-Body Database Browser: 90377 Sedna (2003 VB12)" (2020-01-21 last obs). Archived from the original on 27 February 2020. Retrieved 27 February 2020.
  3. ^ a b Buie, Marc W. (22 November 2009). "Orbit Fit and Astrometric record for 90377". Deep Ecliptic Survey. Archived from the original on 20 May 2011. Retrieved 17 January 2006.
  4. ^ Slyuta, E. N.; Kreslavsky, M. A. (1990). Intermediate (20–100 KM ) Sized Volcanic Edifices on Venus (PDF). Lunar and planetary science XXI. Lunar and Planetary Institute. p. 1174. Archived (PDF) from the original on 15 January 2021. Retrieved 29 February 2020(for Sedna Planitia){{cite conference}}: CS1 maint: postscript (link)
  5. ^ a b c d e f g h Horizons output. "Barycentric Osculating Orbital Elements for 90377 Sedna (2003 VB12)". Archived from the original on 17 October 2023. Retrieved 18 September 2021. (Solution using the Solar System barycenter. Select Ephemeris Type:Elements and Center:@0) (Saved Horizons output file 2011-Feb-04 "Barycentric Osculating Orbital Elements for 90377 Sedna". Archived from the original on 19 November 2012.) In the second pane "PR=" can be found, which gives the orbital period in days (4.160E+06, which is 11,390 Julian years).
  6. ^ a b c d e "Horizons Batch for Sedna in July 2076" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 11 April 2021. Retrieved 10 April 2021. (JPL#34/Soln.date: 2021-Apr-13)
  7. ^ a b "Sedna Ephemerides for July 2076". AstDyS. Archived from the original on 3 January 2021. Retrieved 31 December 2020. ("R (au) column" is distance from Sun)
  8. ^ a b c Lellouch, E.; Santos-Sanz, P.; Lacerda, P.; Mommert, M.; Duffard, R.; Ortiz, J. L.; Müller, T. G.; Fornasier, S.; Stansberry, J.; Kiss, Cs.; Vilenius, E.; Mueller, M.; Peixinho, N.; Moreno, R.; Groussin, O. (29 September 2013). ""TNOs are Cool": A survey of the trans-Neptunian region: IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations⋆⋆⋆". Astronomy & Astrophysics. 557: A60. Bibcode:2013A&A...557A..60L. doi:10.1051/0004-6361/201322047. hdl:10316/80307. ISSN 0004-6361.
  9. ^ a b Rommel, Flavia L.; Braga-Ribas, Felipe; Desmars, Josselin; Camargo, Julio I. B.; Ortiz, Jose-Luis; Sicardy, Bruno (December 2020). "Stellar occultations enable milliarcsecond astrometry for Trans-Neptunian objects and Centaurs". Astronomy & Astrophysics. 644: 15. arXiv:2010.12708. Bibcode:2020A&A...644A..40R. doi:10.1051/0004-6361/202039054. S2CID 225070222. A40.
  10. ^ a b Gaudi, B. Scott; Stanek, Krzysztof Z.; Hartman, Joel D.; Holman, Matthew J.; McLeod, Brian A. (2005). "On the Rotation Period of (90377) Sedna". The Astrophysical Journal. 629 (1): L49–L52. arXiv:astro-ph/0503673. Bibcode:2005ApJ...629L..49G. doi:10.1086/444355. S2CID 55713175.
  11. ^ Tegler, Stephen C. (26 January 2006). "Kuiper Belt Object Magnitudes and Surface Colors". Northern Arizona University. Archived from the original on 1 September 2006. Retrieved 5 November 2006.
  12. ^ a b "AstDys (90377) Sedna Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 31 October 2023. Retrieved 31 October 2023.
  13. ^ JPL Horizons On-Line Ephemeris System (18 July 2010). "Horizons Output for Sedna 2076/2114". Archived from the original on 25 February 2012. Retrieved 18 July 2010. Horizons Archived 12 September 2015 at the Wayback Machine
  14. ^ a b c Pál, A.; Kiss, C.; Müller, T. G.; Santos-Sanz, P.; Vilenius, E.; Szalai, N.; Mommert, M.; Lellouch, E.; Rengel, M.; Hartogh, P.; Protopapa, S.; Stansberry, J.; Ortiz, J.-L.; Duffard, R.; Thirouin, A.; Henry, F.; Delsanti, A. (2012). ""TNOs are Cool": A survey of the trans-Neptunian region. VII. Size and surface characteristics of (90377) Sedna and 2010 EK139". Astronomy & Astrophysics. 541: L6. arXiv:1204.0899. Bibcode:2012A&A...541L...6P. doi:10.1051/0004-6361/201218874. S2CID 119117186.
  15. ^ "Star Maps of Asteroid 90377 Sedna (2003 VB12) | TheSkyLive". 10 January 2024. Archived from the original on 10 January 2024. Retrieved 10 January 2024.
  16. ^ a b McGranaghan, R.; Sagan, B.; Dove, G.; Tullos, A.; Lyne, J. E.; Emery, J. P. (2011). "A Survey of Mission Opportunities to Trans-Neptunian Objects". Journal of the British Interplanetary Society. 64: 296–303. Bibcode:2011JBIS...64..296M.
  17. ^ a b Fussman, Cal (2006). "The Man Who Finds Planets". Discover. Archived from the original on 16 June 2010. Retrieved 22 May 2010.
  18. ^ Chang, Kenneth (21 January 2016). "Ninth Planet May Exist Beyond Pluto, Scientists Report". The New York Times. p. A1. Archived from the original on 9 October 2016. Retrieved 1 March 2017.
  19. ^ a b c d e f g Brown, Mike; Rabinowitz, David; Trujillo, Chad (2004). "Discovery of a Candidate Inner Oort Cloud Planetoid". Astrophysical Journal. 617 (1): 645–649. arXiv:astro-ph/0404456. Bibcode:2004ApJ...617..645B. doi:10.1086/422095. S2CID 7738201.
  20. ^ Lakdawalla, Emily (26 March 2014). "A second Sedna! What does it mean?". Planetary Society. Archived from the original on 10 December 2018. Retrieved 1 April 2023.
  21. ^ a b Batygin, Konstantin; Brown, Michael E. (2016). "Evidence for a Distant Giant Planet in the Solar System". The Astronomical Journal. 151 (2): 22. arXiv:1601.05438. Bibcode:2016AJ....151...22B. doi:10.3847/0004-6256/151/2/22. S2CID 2701020.
  22. ^ "MPEC 2004-E45 : 2003 VB12". IAU: Minor Planet Center. 15 March 2004. Archived from the original on 28 October 2021. Retrieved 27 March 2018.
  23. ^ a b Brown, Michael E. (2012). How I Killed Pluto And Why It Had It Coming. New York: Spiegel & Grau. p. 96. ISBN 978-0-385-53110-8.
  24. ^ a b c d Brown, Mike. "Sedna". Caltech. Archived from the original on 25 July 2010. Retrieved 20 July 2010.
  25. ^ a b "MPEC 2004-S73: Editorial Notice". IAU Minor Planet Center. 2004. Archived from the original on 8 May 2020. Retrieved 18 July 2010.
  26. ^ Walker, Duncan (16 March 2004). "How do planets get their names?". BBC News. Archived from the original on 19 December 2006. Retrieved 22 May 2010.
  27. ^ "MPC 52733" (PDF). Minor Planet Center. 2004. Archived (PDF) from the original on 25 July 2011. Retrieved 30 August 2010.
  28. ^ "Miscellaneous Symbols and Arrows" (PDF). unicode.org. Unicode. 1991–2021. Archived (PDF) from the original on 2 August 2022. Retrieved 6 August 2022. 2BF2 ⯲ SEDNA
  29. ^ a b Faulks, David (12 June 2016). "Eris and Sedna Symbols" (PDF). unicode.org. Archived from the original (PDF) on 8 May 2017.
  30. ^ "SBDB Epoch 2019". JPL. Archived from the original on 13 November 2019.
  31. ^ Kaib, Nathan A.; Becker, Andrew C.; Jones, R. Lynne; Puckett, Andrew W.; Bizyaev, Dmitry; Dilday, Benjamin; Frieman, Joshua A.; Oravetz, Daniel J.; Pan, Kaike; Quinn, Thomas; Schneider, Donald P.; Watters, Shannon (2009). "2006 SQ372: A Likely Long-Period Comet from the Inner Oort Cloud". The Astrophysical Journal. 695 (1): 268–275. arXiv:0901.1690. Bibcode:2009ApJ...695..268K. doi:10.1088/0004-637X/695/1/268. S2CID 16987581.
  32. ^ "Mysterious Sedna | Science Mission Directorate". science.nasa.gov. Archived from the original on 16 May 2017. Retrieved 31 March 2023.
  33. ^ "Most Distant Object in Solar System Discovered". NASA Jet Propulsion Laboratory (JPL). 15 March 2004. Archived from the original on 22 October 2023. Retrieved 31 March 2023.
  34. ^ Apparent magnitude of Sun at 937 AU = -26.74 + 5log(937) = -11.88 Full moon magnitude = -12.74 Ratio = 10^(0.4*(11.88-12.74)) = 0.453 ≈ 45%.
  35. ^ Trujillo, Chadwick A.; Brown, M. E.; Rabinowitz, D. L. (2007). "The Surface of Sedna in the Near-infrared". Bulletin of the American Astronomical Society. 39: 510. Bibcode:2007DPS....39.4906T.
  36. ^ a b Trujillo, Chadwick A.; Sheppard, S. S. (2014). "A Sedna-like body with a perihelion of 80 astronomical units". Nature. 507 (7493): 471–474. Bibcode:2014Natur.507..471T. doi:10.1038/nature13156. PMID 24670765. S2CID 4393431.
  37. ^ Calculated: https://www.wolframalpha.com/input?i=G*solar+mass%2FAU%281%2F76.19-1%2F937%29%3D1%2F2*%28x+m%2Fs%29%5E2%28%28937%2F76.19%29%5E2-1%29
  38. ^ 377.4 m/s for Sedna divided by 29.78 km/s for Earth.
  39. ^ "AstDys (90377) Sedna Ephemerides 2003-11-14". Department of Mathematics, University of Pisa, Italy. Archived from the original on 22 October 2023. Retrieved 6 July 2019.
  40. ^ "AstDys (136199) Eris Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 31 October 2023. Retrieved 31 October 2023.
  41. ^ "AstDys (225088) 2007 OR10 Ephemerides". Department of Mathematics, University of Pisa, Italy. Archived from the original on 31 October 2023. Retrieved 31 October 2023.
  42. ^ "Long View from a Lonely Planet". Hubblesite, STScI-2004-14. 2004. Archived from the original on 21 November 2022. Retrieved 21 July 2010.
  43. ^ a b "Hubble Observes Planetoid Sedna, Mystery Deepens". Hubblesite, STScI-2004-14. 2004. Archived from the original on 12 November 2016. Retrieved 30 August 2010.
  44. ^ a b Brown, Michael E. (2008). "The largest Kuiper belt objects" (PDF). In Barucci, M. Antonietta; Boehnhardt, Hermann; Cruikshank, Dale P. (eds.). The Solar System Beyond Neptune. University of Arizona Press. pp. 335–345. ISBN 978-0-8165-2755-7. Archived (PDF) from the original on 13 November 2012. Retrieved 19 September 2008.
  45. ^ Grundy, W. M.; Noll, K. S.; Stephens, D. C. (2005). "Diverse Albedos of Small Trans-Neptunian Objects". Icarus. 176 (1). Lowell Observatory, Space Telescope Science Institute: 184–191. arXiv:astro-ph/0502229. Bibcode:2005Icar..176..184G. doi:10.1016/j.icarus.2005.01.007. S2CID 118866288. Archived from the original on 29 October 2023. Retrieved 21 June 2023.
  46. ^ Stansberry, John; Grundy, Will; Brown, Mike; Cruikshank, Dale; Spencer, John; Trilling, David; Margot, Jean-Luc (2008). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope" (PDF). In Barucci, M. Antonietta; Boehnhardt, Hermann; Cruikshank, Dale P. (eds.). The Solar System Beyond Neptune. University of Arizona Press. pp. 161–179. arXiv:astro-ph/0702538v2. Bibcode:2008ssbn.book..161S. ISBN 978-0-8165-2755-7. Archived (PDF) from the original on 25 October 2012. Retrieved 15 August 2010.
  47. ^ a b c d e Emery, J. P.; Ore, C. M. Dalle; Cruikshank, D. P.; Fernández, Y. R.; Trilling, D. E.; Stansberry, J. A. (2007). "Ices on 90377 Sedna: Conformation and compositional constraints". Astronomy and Astrophysics. 406 (1): 395–398. Bibcode:2007A&A...466..395E. doi:10.1051/0004-6361:20067021.
  48. ^ Lakdawalla, E. (19 October 2016). "DPS/EPSC update: 2007 OR10 has a moon!". The Planetary Society. Archived from the original on 16 April 2019. Retrieved 19 October 2016.
  49. ^ Brown, Michael E. (16 March 2004). "Characterization of a planetary-sized body in the inner Oort cloud – HST Proposal 10041". Archived from the original on 4 May 2022. Retrieved 27 March 2018.
  50. ^ "Hubble Observes Planetoid Sedna, Mystery Deepens". Space Telescope Science Institute. 14 April 2004. Archived from the original on 29 March 2018. Retrieved 27 March 2018.
  51. ^ Bannister, Michelle [@astrokiwi] (27 March 2018). "#TNO2018" (Tweet). Retrieved 27 March 2018 – via Twitter. the census of dwarf planet satellites shows all the biggest systems seem to have satellites. Sedna isn't known to, but any satellite would spend at least a quarter of its time lost in Sedna's glare [...] no additional satellites for Makemake, Eris and OR10 down to 26th mag. Haumea has already been checked. Sedna the last remaining to double-check!
  52. ^ a b c Trujillo, Chadwick A.; Brown, Michael E.; Rabinowitz, David L.; Geballe, Thomas R. (2005). "Near-Infrared Surface Properties of the Two Intrinsically Brightest Minor Planets: (90377) Sedna and (90482) Orcus". The Astrophysical Journal. 627 (2): 1057–1065. arXiv:astro-ph/0504280. Bibcode:2005ApJ...627.1057T. doi:10.1086/430337. S2CID 9149700.
  53. ^ Sheppard, Scott S. (2010). "The colors of extreme outer Solar System objects". The Astronomical Journal. 139 (4): 1394–1405. arXiv:1001.3674. Bibcode:2010AJ....139.1394S. doi:10.1088/0004-6256/139/4/1394. S2CID 53545974.
  54. ^ Barucci, M. A.; Cruikshank, D. P.; Dotto, E.; Merlin, F.; Poulet, F.; Dalle Ore, C.; Fornasier, S.; De Bergh, C. (2005). "Is Sedna another Triton?". Astronomy & Astrophysics. 439 (2): L1–L4. Bibcode:2005A&A...439L...1B. doi:10.1051/0004-6361:200500144.
  55. ^ a b Barucci, M. A.; Morea Dalle Ore, C.; Alvarez-Candal, A.; de Bergh, C.; Merlin, F.; Dumas, C.; Cruikshank, D. (December 2010). "(90377) Sedna: Investigation of Surface Compositional Variation". The Astronomical Journal. 140 (6): 2095–2100. Bibcode:2010AJ....140.2095B. doi:10.1088/0004-6256/140/6/2095. S2CID 120483473.
  56. ^ Emery, J. P.; Wong, I.; Brunetto, R.; Cook, J. C.; Pinilla-Alonso, N.; Stansberry, J. A.; Holler, B. J.; Grundy, W. M.; Protopapa, S.; Souza-Feliciano, A. C.; Fernández-Valenzuela, E.; Lunine, J. I.; Hines, D. C. (2024). "A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy". Icarus. 414. arXiv:2309.15230. Bibcode:2024Icar..41416017E. doi:10.1016/j.icarus.2024.116017.
  57. ^ Jewitt, David; Morbidelli, Alessandro; Rauer, Heike (2007). Trans-Neptunian Objects and Comets: Saas-Fee Advanced Course 35. Swiss Society for Astrophysics and Astronomy. Berlin: Springer. p. 86. arXiv:astro-ph/0512256v1. Bibcode:2005astro.ph.12256M. ISBN 978-3-540-71957-1.
  58. ^ Lykawka, Patryk Sofia; Mukai, Tadashi (2007). "Dynamical classification of trans-Neptunian objects: Probing their origin, evolution, and interrelation". Icarus. 189 (1): 213–232. Bibcode:2007Icar..189..213L. doi:10.1016/j.icarus.2007.01.001.
  59. ^ Stern, S. Alan (2005). "Regarding the accretion of 2003 VB12 (Sedna) and like bodies in distant heliocentric orbits". The Astronomical Journal. 129 (1): 526–529. arXiv:astro-ph/0404525. Bibcode:2005AJ....129..526S. doi:10.1086/426558. S2CID 119430069.
  60. ^ Sheppard, Scott S.; Jewitt, David C. (2005). "Small Bodies in the Outer Solar System" (PDF). Frank N. Bash Symposium. The University of Texas at Austin. Archived from the original (PDF) on 16 July 2010. Retrieved 25 March 2008.
  61. ^ Brown, Michael E. (2004). "Sedna and the birth of the solar system". Bulletin of the American Astronomical Society. 36 (127.04): 1553. Bibcode:2004AAS...20512704B.
  62. ^ a b "Transneptunian Object 90377 Sedna (formerly known as 2003 VB12)". The Planetary Society. Archived from the original on 25 November 2009. Retrieved 3 January 2010.
  63. ^ a b c d e Morbidelli, Alessandro; Levison, Harold F. (2004). "Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna)". The Astronomical Journal. 128 (5): 2564–2576. arXiv:astro-ph/0403358. Bibcode:2004AJ....128.2564M. doi:10.1086/424617. S2CID 119486916.
  64. ^ a b Kenyon, Scott J.; Bromley, Benjamin C. (2 December 2004). "Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits". Nature. 432 (7017): 598–602. arXiv:astro-ph/0412030. Bibcode:2004Natur.432..598K. doi:10.1038/nature03136. PMID 15577903. S2CID 4427211. Archived from the original on 29 October 2023. Retrieved 21 June 2023.
  65. ^ "The Challenge of Sedna". Harvard-Smithsonian Center for Astrophysics. Archived from the original on 25 August 2012. Retrieved 26 March 2009.
  66. ^ a b Gomes, Rodney S.; Matese, John J.; Lissauer, Jack J. (2006). "A distant planetary-mass solar companion may have produced distant detached objects". Icarus. 184 (2): 589–601. Bibcode:2006Icar..184..589G. doi:10.1016/j.icarus.2006.05.026.
  67. ^ Lykawka, P. S.; Mukai, T. (2008). "An Outer Planet Beyond Pluto and the Origin of the Trans-Neptunian Belt Architecture". The Astronomical Journal. 135 (4): 1161–1200. arXiv:0712.2198. Bibcode:2008AJ....135.1161L. doi:10.1088/0004-6256/135/4/1161. S2CID 118414447.
  68. ^ a b Schwamb, Megan E. (2007). "Searching for Sedna's Sisters: Exploring the inner Oort cloud" (PDF) (Preprint). Caltech. Archived from the original (PDF) on 12 May 2013. Retrieved 6 August 2010.
  69. ^ Fesenmaier, Kimm (20 January 2016). "Caltech Researchers Find Evidence of a Real Ninth Planet" (Press release). Archived from the original on 16 January 2019. Retrieved 13 September 2017.
  70. ^ a b Brown, Michael E.; Batygin, Konstantin (31 January 2022). "A search for Planet Nine using the Zwicky Transient Facility public archive". The Astronomical Journal. 163 (2): 102. arXiv:2110.13117. Bibcode:2022AJ....163..102B. doi:10.3847/1538-3881/ac32dd. S2CID 239768690.
  71. ^ Croswell, Ken (2015). "Sun Accused of Stealing Planetary Objects from Another Star". Scientific American. 313 (3): 23. doi:10.1038/scientificamerican0915-23. PMID 26455093. Archived from the original on 8 June 2021. Retrieved 15 January 2023.
  72. ^ Schilling, Govert (19 June 2015). "Grand Theft Sedna: how the sun might have stolen a mini-planet". New Scientist. Archived from the original on 20 December 2021. Retrieved 15 January 2023.
  73. ^ Dickinson, David (6 August 2015). "Stealing Sedna". universetoday. Archived from the original on 15 November 2021. Retrieved 15 January 2023.
  74. ^ a b c Schwamb, Megan E.; Brown, Michael E.; Rabinowitz, David L. (2009). "A Search for Distant Solar System Bodies in the Region of Sedna". The Astrophysical Journal Letters. 694 (1): L45–L48. arXiv:0901.4173. Bibcode:2009ApJ...694L..45S. doi:10.1088/0004-637X/694/1/L45. S2CID 15072103.
  75. ^ "JPL Small-Body Database Browser: (2012 VP113)" (2013-10-30 last obs). Jet Propulsion Laboratory. Archived from the original on 9 June 2014. Retrieved 26 March 2014.
  76. ^ "A new object at the edge of our Solar System discovered". Physorg.com. 26 March 2014. Archived from the original on 20 June 2016. Retrieved 27 March 2014.
  77. ^ "New extremely distant Solar System object found during hunt for Planet X". Carnegie Institution for Science. 2 October 2018. Archived from the original on 1 December 2020. Retrieved 24 January 2021.
  78. ^ Sheppard, Scott S.; Trujillo, Chadwick A.; Tholen, David J.; Kaib, Nathan (April 2019). "A New High Perihelion Trans-Plutonian Inner Oort Cloud Object: 2015 TG387". The Astronomical Journal. 157 (4): 139. arXiv:1810.00013. Bibcode:2019AJ....157..139S. doi:10.3847/1538-3881/ab0895. ISSN 0004-6256. S2CID 119071596.
  79. ^ Rice, Malena; Laughlin, Gregory (December 2020). "Exploring Trans-Neptunian Space with TESS: A Targeted Shift-stacking Search for Planet Nine and Distant TNOs in the Galactic Plane". The Planetary Science Journal. 1 (3): 81 (18 pp.). arXiv:2010.13791. Bibcode:2020PSJ.....1...81R. doi:10.3847/PSJ/abc42c. S2CID 225075671.
  80. ^ Stern, S. Alan; Levison, Harold F. (2002). "Regarding the criteria for planethood and proposed planetary classification schemes" (PDF). Highlights of Astronomy. 12: 205–213, as presented at the XXIVth General Assembly of the IAU–2000 [Manchester, UK, 7–18 August 2000]. Bibcode:2002HiA....12..205S. doi:10.1017/S1539299600013289. Archived (PDF) from the original on 23 September 2015. Retrieved 6 August 2010.
  81. ^ Lakdawalla, Emily; et al. (21 April 2020). "What Is A Planet?". The Planetary Society. Archived from the original on 22 January 2022. Retrieved 15 January 2023.
  82. ^ Rambaux, Nicolas; Baguet, Daniel; Chambat, Frederic; Castillo-Rogez, Julie C. (15 November 2017). "Equilibrium Shapes of Large Trans-Neptunian Objects". The Astrophysical Journal. 850 (1): L9. Bibcode:2017ApJ...850L...9R. doi:10.3847/2041-8213/aa95bd. ISSN 2041-8213. S2CID 62822239.
  83. ^ Rabinowitz, David L.; Schaefer, B.; Tourtellotte, S.; Schaefer, M. (May 2011). "SMARTS Studies of the Composition and Structure of Dwarf Planets". Bulletin of the American Astronomical Society. 43. Bibcode:2011AAS...21820401R.
  84. ^ Malhotra, Renu (May 2009). "On the Importance of a Few Dwarf Planets". Bulletin of the American Astronomical Society. 41: 740. Bibcode:2009AAS...21423704M.
  85. ^ Tancredi, G.; Favre, S. (2008). "Which are the dwarfs in the solar system?" (PDF). Asteroids, Comets, Meteors. Archived (PDF) from the original on 3 June 2016. Retrieved 5 January 2011.
  86. ^ Brown, Michael E. (23 September 2011). "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Archived from the original on 18 October 2011. Retrieved 23 September 2011.
  87. ^ Grundy, W. M.; Noll, K. S.; Buie, M. W.; Benecchi, S. D.; Ragozzine, D.; Roe, H. G. (December 2019). "The mutual orbit, mass, and density of transneptunian binary Gǃkúnǁʼhòmdímà ((229762) 2007 UK126)" (PDF). Icarus. 334: 30–38. doi:10.1016/j.icarus.2018.12.037. S2CID 126574999. Archived (PDF) from the original on 7 April 2019.
  88. ^ "List Of Transneptunian Objects". Minor Planet Center. 21 June 2022. Archived from the original on 12 June 2018. Retrieved 28 June 2022.
  89. ^ "Small-Body Database Lookup". ssd.jpl.nasa.gov. Archived from the original on 6 October 2021. Retrieved 28 June 2022.
  90. ^ Gladman, Brett J. (2001). "Evidence for an Extended Scattered Disk?". Observatoire de la Côte d'Azur. Archived from the original on 4 February 2012. Retrieved 22 July 2010.
  91. ^ Delsanti, Audrey; Jewitt, David (2006). "The Solar System Beyond The Planets". Solar System Update : Topical and Timely Reviews in Solar System Sciences. Springer Praxis Books. Springer-Praxis Ed. pp. 267–293. doi:10.1007/3-540-37683-6_11. ISBN 978-3-540-26056-1.
  92. ^ Elliot, J. L.; Kern, S. D.; Clancy, K. B.; Gulbis, A. A. S.; Millis, R. L.; Buie, M. W.; Wasserman, L. H.; Chiang, E. I.; Jordan, A. B.; Trilling, D. E.; Meech, K. J. (2006). "The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population". The Astronomical Journal. 129 (2): 1117. Bibcode:2005AJ....129.1117E. doi:10.1086/427395.
  93. ^ Zubko, Vladislav (March 2022). "The fastest routes of approach to dwarf planet Sedna for study its surface and composition at the close range". Acta Astronautica. 192: 47–67. arXiv:2112.11506. Bibcode:2022AcAau.192...47Z. doi:10.1016/j.actaastro.2021.12.011. S2CID 245172065.
  94. ^ Zubko, V. A.; Sukhanov, A. A.; Fedyaev, K. S.; Koryanov, V. V.; Belyaev, A. A. (October 2021). "Analysis of mission opportunities to Sedna in 2029–2034". Advances in Space Research. 68 (7): 2752–2775. arXiv:2112.13017. Bibcode:2021AdSpR..68.2752Z. doi:10.1016/j.asr.2021.05.035. S2CID 236278655. Archived from the original on 2 April 2022. Retrieved 11 July 2022.
  95. ^ Brickley, Samuel; Domenech, Iliane; Franceschetti, Lorenzo; Sarappo, John; Lyne, James Evans (May 2023). "Investigation of Interplanetary Trajectories to Sedna". AAS 23-420, AAS/AIAA Astrodynamics Specialist Conference, Big Sky, Montana, August 2023. Archived from the original on 2 September 2023. Retrieved 1 September 2023.

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