Planets beyond Neptune

45: 7803: 883:. It was found that the hypothetical object's mass had to exceed 5 Earth masses to break the resonance, and the parameter space is quite large and a large variety of objects could have existed beyond Pluto without disturbing the resonance. Four test orbits of a trans-Plutonian planet have been integrated forward for four million years in order to determine the effects of such a body on the stability of the Neptune–Pluto 3:2 resonance. Planets beyond Pluto with masses of 0.1 and 1.0 Earth masses in orbits at 48.3 and 75.5 AU, respectively, do not disturb the 3:2 resonance. Test planets of 5 Earth masses with semi-major axes of 52.5 and 62.5 AU disrupt the four-million-year libration of Pluto's argument of perihelion. 7675: 5812: 1507:, it has been confirmed that a statistically significant (62σ) asymmetry between the shortest mutual ascending and descending nodal distances does exist; in addition, multiple highly improbably (p < 0.0002) correlated pairs of orbits with mutual nodal distances as low as 0.2 AU at 152 AU from the Solar System's barycentre or 1.3 AU at 339 AU have been found. Both findings suggest that massive perturbers may exist at hundreds of AUs from the Sun and are difficult to explain within the context of a uniform distribution of orbital orientations in the outermost Solar System. 148:, astronomers hypothesized the existence of a super-Earth or ice giant planet, 2 to 15 times the mass of the Earth and beyond 200 AU with possibly a highly inclined orbit at some 1,500 AU. In 2016, further work showed this unknown distant planet is likely to be on an inclined, eccentric orbit that goes no closer than about 200 AU and no farther than about 1,200 AU from the Sun. The orbit is predicted to be anti-aligned to the clustered extreme trans-Neptunian objects. Because Pluto is no longer considered a planet by the IAU, this new hypothetical object has become known as 365:. Ketakar suggested that Uranus, Neptune and his hypothetical trans-Neptunian planets were also locked in Laplace-like resonances. This is incorrect; Uranus and Neptune, while in a near-2:1 resonance, are not in full resonance. His calculations predicted a mean distance for Brahma of 38.95 AU and an orbital period of 242.28 Earth years (3:4 resonance with Neptune). When Pluto was discovered 19 years later, its mean distance of 39.48 AU and orbital period of 248 Earth years were close to Ketakar's prediction (Pluto in fact has a 5818: 5806: 1052: 1142: 1077:, or that it was tugged into its current position by a trans-Neptunian planet. The most obvious solution to determining Sedna's peculiar orbit would be to locate a number of objects in a similar region, whose various orbital configurations would provide an indication as to their history. If Sedna had been pulled into its orbit by a trans-Neptunian planet, any other objects found in its region would have a similar perihelion to Sedna (around 80 AU (12 billion km; 7.4 billion mi)). 7851: 555:

lesser-quality photograph taken on January 21 confirmed the movement. Upon confirmation, Tombaugh walked into Slipher's office and declared, "Doctor Slipher, I have found your Planet X." The object lay just six degrees from one of two locations for Planet X Lowell had suggested; thus it seemed he had at last been vindicated. After the observatory obtained further confirmatory photographs, news of the discovery was telegraphed to the

505: 589: 1479:

farther than 970–1,111 AU. Moreover, Iorio stated that the modern ephemerides of the Solar System outer planets has provided even tighter constraints: no celestial body with a mass of 15 times that of Earth can exist closer than 1,100–1,300 AU. However, work by another group of astronomers using a more comprehensive model of the Solar System found that Iorio's conclusion was only partially correct. Their analysis of

7827: 547: 7651: 7663: 7839: 322:, an astronomer with a reputation as an egocentric contrarian, opined "there is certainly one, most likely two and possibly three planets beyond Neptune". Tentatively naming the first planet "Oceanus", he placed their respective distances at 42, 56 and 72 AU from the Sun. He gave no indication as to how he determined their existence, and no known searches were mounted to locate them. 7815: 1436:

accidentally discovered a massive outer Solar System object in its tiny, tiny, tiny, field of view, that would suggest that there are something like 200,000 Earth-sized planets in the outer Solar System ... Even better, I just realized that this many Earth-sized planets existing would destabilize the entire Solar System and we would all die."

1257:". The Kuiper belt terminates suddenly at a distance of 48 AU (7.2 billion km; 4.5 billion mi) from the Sun. Brunini and Melita have speculated that this sudden drop-off may be attributed to the presence of an object with a mass between those of Mars and Earth located beyond 48 AU. 1423:(ALMA) detected a brief series of 350 GHz pulses that they concluded must either be a series of independent sources, or a single, fast moving source. Deciding that the latter was the most likely, they calculated based on its speed that, were it bound to the Sun, the object, which they named "Gna" after a 1412:, whereas others would be orbiting in a halo around the Solar System, with orbital periods of millions of years. This halo would lie at between 1,000 and 10,000 AU (150 and 1,500 billion km; 93 and 930 billion mi) from the Sun, or between a third and a thirtieth the distance to the 1234:

Even without gravitational evidence, Mike Brown, the discoverer of Sedna, has argued that Sedna's 12,000-year orbit means that probability alone suggests that an Earth-sized object exists beyond Neptune. Sedna's orbit is so eccentric that it spends only a small fraction of its orbital period near the

1194:

suggested that the available data actually indicates more than one trans-Neptunian planet; subsequent work further suggests that the evidence is robust enough but rather than connected with the longitudes of the ascending nodes and the arguments of perihelia, semi-major axes and nodal distances could

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showed that the irregularities observed in Uranus's orbit virtually disappeared once the planet's displacement of longitude was taken into account. Lowell himself, despite his close association with Pickering, dismissed Planet O out of hand, saying, "This planet is very properly designated "O",

232:

raised an objection to Le Verrier's calculations, claiming that Neptune's observed mass was smaller and its orbit larger than Le Verrier had initially predicted. He postulated, based largely on simple subtraction from Le Verrier's calculations, that another planet of roughly 12 Earth masses, which he

1110:

In 2012, Rodney Gomes modelled the orbits of 92 Kuiper belt objects and found that six of those orbits were far more elongated than the model predicted. He concluded that the simplest explanation was the gravitational pull of a distant planetary companion, such as a Neptune-sized object at 1,500 AU.

1036:

Although most astronomers accept that Lowell's Planet X does not exist, a number have revived the idea that a large unseen planet could create observable gravitational effects in the outer Solar System. These hypothetical objects are often referred to as "Planet X", although the conception

813:

of the U.S. Naval Observatory, to measure the mass of the Pluto–Charon system directly by observing the moon's orbital motion around Pluto. They determined Pluto's mass to be 1.31×10 kg; roughly one five-hundredth that of Earth or one-sixth that of the Moon, and far too small to account for the

307:

who, after studying the data on the orbit of Uranus from 1690 to 1895, concluded that one trans-Neptunian planet alone could not account for the discrepancies in its orbit, and postulated the positions of two planets he believed were responsible. The second was launched when Gabriel Dallet suggested

283:

concluded on the basis of this evidence that two planets must exist beyond Neptune. He calculated, based on the fact that four comets possessed aphelia at around 100 AU and a further six with aphelia clustered at around 300 AU, the orbital elements of a pair of hypothetical trans-Neptunian

104:

spacecraft found that the irregularities observed in Uranus's orbit were due to a slight overestimation of Neptune's mass. After 1992, the discovery of numerous small icy objects with similar or even wider orbits than Pluto led to a debate over whether Pluto should remain a planet, or whether it and

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was discovered, its extreme orbit raised questions about its origin. Its perihelion is so distant (approximately 76 AU (11.4 billion km; 7.1 billion mi)) that no currently observed mechanism can explain Sedna's eccentric distant orbit. It is too far from the planets to have

436:

where the other planets in the Solar System lie. Using a 5-inch photographic camera, he manually examined over 200 three-hour exposures with a magnifying glass, and found no planets. At that time Pluto was too far above the ecliptic to be imaged by the survey. After revising his predicted possible

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not gravitationally bound to the Sun, and as far away as 4000 AU, it could be much larger. The paper was never formally accepted, and has been withdrawn until the detection is confirmed. Scientists' reactions to the notice were largely sceptical; Mike Brown commented that, "If it is true that ALMA

1407:

states that there were hundreds of planet-sized objects, known as oligarchs, in the early stages of the Solar System's evolution. In 2005, astronomer Eugene Chiang speculated that although some of these oligarchs became the planets we know today, most would have been flung outward by gravitational

870:

space observatory made headlines briefly in 1983 due to an "unknown object" that was at first described as "possibly as large as the giant planet Jupiter and possibly so close to Earth that it would be part of this Solar System". Further analysis revealed that of several unidentified objects, nine

679:

and E.C. Bower as early as 1934. However, because Triton's mass was then believed to be roughly 2.5% of the Earth–Moon system (more than ten times its actual value), Rawlins's determination for Pluto's mass was similarly incorrect. It was nonetheless a meagre enough value for him to conclude Pluto

626:

suggested that Pluto's dimness and high orbital eccentricity made it more similar to an asteroid or comet: "The Lowell result confirms the possible high eccentricity announced by us on April 5. Among the possibilities are a large asteroid greatly disturbed in its orbit by close approach to a major

452:

Separately, in 1908, Pickering announced that, by analysing irregularities in Uranus's orbit, he had found evidence for a ninth planet. His hypothetical planet, which he termed "Planet O" (because it came after "N", i.e. Neptune), possessed a mean orbital radius of 51.9 AU and an orbital

124:

While the astronomical community widely agrees that Planet X, as originally envisioned, does not exist, the concept of an as-yet-unobserved planet has been revived by a number of astronomers to explain other anomalies observed in the outer Solar System. As of March 2014, observations with the

1478:

of the perihelia of Saturn, Earth, and Mars, Lorenzo Iorio concluded that any unknown planet with a mass of 0.7 times that of Earth must be farther than 350–400 AU; one with a mass of 2 times that of Earth, farther than 496–570 AU; and finally one with a mass of 15 times that of Earth,

1239:

Sedna is about three-quarters the size of Pluto. If there are sixty objects three-quarters the size of Pluto then there are probably forty objects the size of Pluto ... If there are forty objects the size of Pluto, then there are probably ten that are twice the size of Pluto. There are probably

512:

Lowell's sudden death in 1916 temporarily halted the search for Planet X. Failing to find the planet, according to one friend, "virtually killed him". Lowell's widow, Constance, engaged in a legal battle with the observatory over Lowell's legacy which halted the search for Planet X for

97:

in 1930 appeared to validate Lowell's hypothesis, and Pluto was officially named the ninth planet. In 1978, Pluto was conclusively determined to be too small for its gravity to affect the giant planets, resulting in a brief search for a tenth planet. The search was largely abandoned in the early

878:

In 1988, A. A. Jackson and R. M. Killen studied the stability of Pluto's resonance with Neptune by placing test "Planet X-es" with various masses and at various distances from Pluto. Pluto and Neptune's orbits are in a 3:2 resonance, which prevents their collision or even any close approaches,

1298:

Although some astronomers, such as Renu Malhotra and David Jewitt, have cautiously supported these claims, others, such as Alessandro Morbidelli, have dismissed them as "contrived". Malhotra & Volk (2017) argued that an unexpected variance in inclination for KBOs farther than the cliff at

554:

By the beginning of 1930, Tombaugh's search had reached the constellation of Gemini. On 18 February 1930, after searching for nearly a year and examining nearly 2 million stars, Tombaugh discovered a moving object on photographic plates taken on 23 January and 29 January of that year. A

599:

To the observatory's disappointment and surprise, Pluto showed no visible disc; it appeared as a point, no different from a star, and, at only 15th magnitude, was six times dimmer than Lowell had predicted, which meant it was either very small, or very dark. Because of Lowell's predictions,

651:

Throughout the mid-20th century, estimates of Pluto's mass were revised downward. In 1931, Nicholson and Mayall calculated its mass, based on its supposed effect on the giant planets, as roughly that of Earth; a value somewhat in accord with the 0.91 Earth mass calculated in 1942 by

315:, Germany proclaimed the existence of a Uranus-sized planet at 50 AU with a 360-year period, which he named Hades, cross-checking with the deviations in the orbit of Uranus. In 1921, Grigull revised his orbital period to 310–330 years, to better fit the observed deviations. 213:, the British Astronomer Royal. Hussey reported that when he suggested to Bouvard that the unusual motion of Uranus might be due to the gravitational influence of an undiscovered planet, Bouvard replied that the idea had occurred to him, and that he had corresponded with 1260:

The presence of an object with a mass similar to that of Mars in a circular orbit at 60 AU (9.0 billion km; 5.6 billion mi) leads to a trans-Neptunian object population incompatible with observations. For instance, it would severely deplete the

862:

attacked the hypothesis, showing that Halley's Comet randomly and irregularly ejects jets of material, causing changes to its own orbital trajectory, and that such a massive object as Brady's Planet X would have severely affected the orbits of known outer planets.

542:

for objects beyond Earth's orbit is at its strongest. He also took a third image as a control to eliminate any false results caused by defects in an individual plate. Tombaugh decided to image the entire zodiac, rather than focus on those regions suggested by Lowell.

416:

for 10 (at the time, Planet X would have been the ninth planet). Lowell's hope in tracking down Planet X was to establish his scientific credibility, which had eluded him due to his widely derided belief that channel-like features visible on the surface of

1280:, ejected outward by Neptune early in the Solar System's formation and currently in an elongated orbit between 101 and 200 AU (15.1 and 29.9 billion km; 9.4 and 18.6 billion mi) from the Sun, could explain the Kuiper cliff and the peculiar 244:, noted that he had "lost" a star he had observed, GR1719k, which Lt. Matthew Maury, the superintendent of the Observatory, claimed was evidence that it must be a new planet. Subsequent searches failed to recover the "planet" in a different position, and in 1878, 826:

In the 1980s and 1990s, Robert Harrington led a search to determine the real cause of the apparent irregularities. He calculated that any Planet X would be at roughly three times the distance of Neptune from the Sun; its orbit would be highly

635:

wrote that Pluto was a "member of the Solar System not comparable with known asteroids and comets, and perhaps of greater importance to cosmogony than would be another major planet beyond Neptune." In 1931, after examining the structure of the

233:

named "Hyperion", must exist beyond Neptune. Le Verrier denounced Babinet's hypothesis, saying, " absolutely nothing by which one could determine the position of another planet, barring hypotheses in which imagination played too large a part."

185:

to analyse perturbations in the orbit of Uranus, and hypothesised that they were caused by the gravitational pull of a yet-undiscovered planet. Le Verrier predicted the position of this new planet and sent his calculations to German astronomer

1244:

However, Brown notes that even though it might approach or exceed Earth in size, should such an object be found it would still be a "dwarf planet" by the current definition, because it would not have cleared its neighbourhood sufficiently.

1235:

Sun, where it can be easily observed. This means that unless its discovery was a freak accident, there is probably a substantial population of objects roughly Sedna's diameter yet to be observed in its orbital region. Mike Brown noted that

537:

illusion of the movement of any planetary body. To reduce the chances that a faster-moving (and thus closer) object be mistaken for the new planet, Tombaugh imaged each region near its opposition point, 180 degrees from the Sun, where the

441:, in which he concluded that Planet X had a mass roughly seven times that of Earth—about half that of Neptune—and a mean distance from the Sun of 43 AU. He assumed Planet X would be a large, low-density object with a high 1361:). An analysis of the TNO data available prior to September 2023 shows that there is a gap at about 72 AU, far from any mean-motion resonances with Neptune. Such a gap may have been induced by a massive perturber located further away. 899:

s 1989 flyby of Neptune, which had revised the planet's total mass downward by 0.5%—an amount comparable to the mass of Mars—to recalculate its gravitational effect on Uranus. When Neptune's newly determined mass was used in the

1306:, residing at the edge of the Solar System, which many news sources began referring to as "Planet Ten". Shortly after it was proposed, Lorenzo Iorio showed that the hypothetical planet's existence cannot be ruled out by 1089:

and orbital period of 1000 years with an inclination of 20° to 40°, was responsible for the structure of the Kuiper belt. They proposed that the perturbations of this planet excited the eccentricities and inclinations of the

995:. They do not orbit the Sun alone, but as part of a population of similarly sized objects. Pluto itself is now recognized as being a member of the Kuiper belt and the largest dwarf planet, larger than the more massive Eris. 608:

could be no less than 0.07 (meaning that, at minimum, it would reflect 7% of the light that hit it), which would have made Pluto about as dark as asphalt, and similar in reflectivity to the least reflective planet, which is

288:, suggesting to many that they might be valid. However, sceptics argued that the orbits of the comets involved were still too uncertain to produce meaningful results. Some have considered Forbes's hypothesis a precursor to 567:

was intended in part to honour Percival Lowell, as his initials made up the word's first two letters. After discovering Pluto, Tombaugh continued to search the ecliptic for other distant objects. He found hundreds of

822:

After 1978, a number of astronomers kept up the search for Lowell's Planet X, convinced that, because Pluto was no longer a viable candidate, an unseen tenth planet must have been perturbing the outer planets.

1028:, should be considered planets in their own right. However, the discovery of Eris did not rehabilitate the Planet X theory because it is far too small to have significant effects on the outer planets' orbits. 1400:(WISE) telescope. In 2014, NASA announced that the WISE survey had ruled out any object with Tyche's characteristics, indicating that Tyche as hypothesized by Matese, Whitman, and Whitmire does not exist. 528:

Tombaugh's task was to systematically capture sections of the night sky in pairs of images. Each image in a pair was taken two weeks apart. He then placed both images of each section in a machine called a

1265:

population. Astronomers have not excluded the possibility of an object with a mass similar to that of Earth located farther than 100 AU (15 billion km; 9.3 billion mi) with an

835:

to the ecliptic—the planet's orbit would be at roughly a 32-degree angle from the orbital plane of the other known planets. This hypothesis was met with a mixed reception. Noted Planet X skeptic

648:) that the presumed irregularities in the orbit of Uranus could not be due to the gravitational effect of a more distant planet, and thus that Lowell's supposed prediction was "purely accidental". 369:). Ketakar made no predictions for the orbital elements other than mean distance and period. It is not clear how Ketakar arrived at these figures, and his second planet, Vishnu, was never located. 928:

that can be attributed to the gravitational pull of a large undiscovered object in the outer Solar System. Today, most astronomers agree that Planet X, as Lowell defined it, does not exist.

1195:

be the signposts. Additional work based on improved orbits of 39 objects still indicates that more than one perturber could be present and that one of them could orbit the Sun at 300-400 AU.

308:

that a single trans-Neptunian planet lying at 47 AU could account for the motion of Uranus. Pickering agreed to examine plates for any suspected planets. In neither case were any found.

613:. This would have given Pluto an estimated mass of no more than 70% that of Earth. Observations also revealed that Pluto's orbit was very elliptical, far more than that of any other planet. 904:(JPL DE), the supposed discrepancies in the Uranian orbit, and with them the need for a Planet X, vanished. There are no discrepancies in the trajectories of any space probes such as 462:

is nothing at all." Unbeknownst to Pickering, four of the photographic plates taken in the search for "Planet O" by astronomers at the Mount Wilson Observatory in 1919 captured images of

3020:

Buie, Marc W.; Grundy, William M.; Young, Eliot F.; Young, Leslie A. & Stern, S. Alan (July 2006). "Orbits and Photometry of Pluto's Satellites: Charon, S/2005 P1, and S/2005 P2".

1485:

data on Saturn's orbital residuals found that observations were inconsistent with a planetary body with the orbit and mass similar to those of Batygin and Brown's Planet Nine having a

3901: 4215: 167: 201:

Even before Neptune's discovery, some speculated that one planet alone was not enough to explain the discrepancy. On 17 November 1834, the British amateur astronomer the Reverend

1160:, a large object with a Sedna-like 4,200-year orbit and a perihelion of roughly 80 AU, which led them to suggest that it offered evidence of a potential trans-Neptunian planet. 1111:

This Neptune-sized object would cause the perihelia of objects with semi-major axes greater than 300 AU to oscillate, delivering them into planet-crossing orbits like those of

7578: 7152: 7548: 513:

several years. In 1925, the observatory obtained glass discs for a new 13 in (33 cm) wide-field telescope to continue the search, constructed with funds from

675:, Dennis Rawlins conjectured Pluto's mass must be similar to Triton's. In retrospect, the conjecture turns out to have been correct; it had been argued by astronomers 7349: 4074: 4013: 4070:"Evidence for a possible bimodal distribution of the nodal distances of the extreme trans-Neptunian objects: avoiding a trans-Plutonian planet or just plain bias?" 1489:

of −130° to −110°, or −65° to 85°. Furthermore, the analysis found that Saturn's orbit is slightly better explained if such a body is located at a true anomaly of

225:, about the subject. Hansen's opinion was that a single body could not adequately explain the motion of Uranus, and postulated that two planets lay beyond Uranus. 616:

Almost immediately, some astronomers questioned Pluto's status as a planet. Barely a month after its discovery was announced, on April 14, 1930, in an article in

1392:. In 2013, Matese and Whitmire re-evaluated the comet data and noted that Tyche, if it existed, would be detectable in the archive of data that was collected by 859: 3205: 4866:

Vlemmings, Wouter; Ramstedt, S.; Maercker, M.; Davidsson, B. (8 December 2015). "The serendipitous discovery of a possible new solar system object with ALMA".

525:, a 22-year-old Kansas farm boy who had only just arrived at the Lowell Observatory after Slipher had been impressed by a sample of his astronomical drawings. 5464: 466:, though this was only recognised years later. Pickering went on to suggest many other possible trans-Neptunian planets up to the year 1932, which he named 404:. In 1906, convinced he could resolve the conundrum of Uranus's orbit, he began an extensive project to search for a trans-Neptunian planet, which he named 2176: 1467:

has continued to take more data since then, and NASA has invited the public to help search this data for evidence of planets beyond these limits, via the

627:

planet such as Jupiter, or it may be one of many long-period planetary objects yet to be discovered, or a bright cometary object." In that same article,

5041:

Fienga, A; Laskar, J; Manche, H; Gastineau, M (23 February 2016). "Constraints on the location of a possible 9th planet derived from the Cassini data".

1085:

In 2008, Tadashi Mukai and Patryk Sofia Lykawka suggested a distant Mars- or Earth-sized planet, currently in a highly eccentric orbit between 100 and

814:

observed discrepancies in the orbits of the outer planets. Lowell's prediction had been a coincidence: If there was a Planet X, it was not Pluto.

3756: 2223:

Musotto, Susanna; Varadi, Ferenc; Moore, William; Schubert, Gerald (October 2002). "Numerical Simulations of the Orbits of the Galilean Satellites".

901: 109:, be given their own separate classification. Although a number of the larger members of this group were initially described as planets, in 2006 the 7883: 7585: 1313:

Starting in 2018, several surveys have discovered multiple objects located beyond the Kuiper Cliff. Some of these new discoveries are close to the

980:

after the Greek goddess of discord and strife), a trans-Neptunian object then thought to be just barely larger than Pluto. Soon afterwards, a NASA

653: 279:, respectively, suggesting that they might mark the orbital radius of an unknown planet that had dragged them into an elliptical orbit. Astronomer 1790: 1240:

three or four that are three times the size of Pluto, and the biggest of these objects ... is probably the size of Mars or the size of the Earth.

843:

pointed out that these discrepancies were a hundredth the size of those noticed by Le Verrier, and could easily be due to observational error.

691:, which is highly reflective. This meant that Pluto, far from being dark, was in fact exceptionally bright, and thus was probably no more than 7893: 7137: 645: 1098:

this planet is posited to have been captured in an outer resonance of Neptune and to have evolved into a higher perihelion orbit due to the

3909: 1299:

50 AU (7.5 billion km; 4.6 billion mi) provided evidence of a possible Mars-sized planet, possibly up to 2.4

4618: 3521: 7282: 1069:

been affected by the gravity of Neptune or the other giant planets and too bound to the Sun to be affected by outside forces such as the

1055:

The orbit of Sedna (red) set against the orbits of Jupiter (orange), Saturn (yellow), Uranus (green), Neptune (blue), and Pluto (purple)

668:

led him to the conclusion that it was midway in size between Mercury and Mars and that its mass was most probably about 0.1 Earth mass.

1008:

mission to Pluto, contend that the IAU's definition is flawed, and that Pluto and Eris, and all large trans-Neptunian objects, such as

6103: 2512: 7048: 1522: 3792:

Patryk S., Lykawka; Tadashi, Mukai (2008). "An Outer Planet Beyond Pluto and the Origin of the Trans-Neptunian Belt Architecture".

4821: 4243: 3442: 7908: 7203: 6848: 6833: 6813: 6125: 6072: 4187: 1444:

As of 2023 the following observations severely constrain the mass and distance of any possible additional Solar System planet:

847: 72: 6121: 6106: 3493: 7898: 7147: 6880: 6843: 6838: 6115: 5259: 5240: 5221: 4483: 3425: 2727: 1643: 1517: 3663: 7918: 7573: 7510: 7164: 6885: 6823: 6818: 6114: 5577: 1385: 237: 6112: 6109: 6105: 6101: 7878: 7727: 6828: 2562: 1545: 1449: 1397: 126: 6119: 6111: 4837: 3694:

Brown, Michael E.; Trujillo, Chadwick; Rabinowitz, David (2004). "Discovery of a Candidate Inner Oort Cloud Planetoid".

2479: 6108: 4737:

Matese, John J.; Whitmire, Daniel P. (2011). "Persistent evidence of a jovian mass solar companion in the Oort cloud".

4292:

The argument about dwarf planet sizes beyond Neptune is 50ᵐ into his talk. The WGBH link doesn't work; view on YouTube.

4131:"Memories of past close encounters in extreme trans-Neptunian space: Finding unseen planets using pure random searches" 2363: 6126: 6122: 44: 6976: 6949: 6117: 4324:"The Existence of a Planet beyond 50 AU and the Orbital Distribution of the Classical Edgeworth–Kuiper-Belt Objects" 3547: 1094:, truncated the planetesimal disk at 48 AU, and detached the orbits of objects like Sedna from Neptune. During 1073:. Hypotheses to explain its orbit include that it was affected by a passing star, that it was captured from another 7913: 7364: 6127: 110: 63:

might exist beyond its orbit. The search began in the mid-19th century and continued at the start of the 20th with

7802: 5811: 2884:

Halliday, Ian; Hardie, R. H.; Franz, Otto G.; Priser, John B. (1966). "An Upper Limit for the Diameter of Pluto".

1739:

Luhman, K. L. (2014). "A Search for a Distant Companion to the Sun with the Wide-field Infrared Survey Explorer".

5532: 5447:"Next steps in understanding the outer solar system: A whitepaper submitted to the 2010 Decadal Survey Committee" 4130: 1475: 241: 7903: 6892: 2837: 2835: 958:

just beyond Neptune. Though none were as large as Pluto, some of these distant trans-Neptunian objects, such as

854:. Brady claimed that they could have been caused by a Jupiter-sized planet beyond Neptune at 59 AU that is in a 7543: 6959: 6793: 3239: 2199: 1504: 1420: 145: 1388:. They argued that evidence of Tyche's existence could be seen in a supposed bias in the points of origin for 7888: 7068: 6964: 4793: 3950:"Extreme trans-Neptunian objects and the Kozai mechanism: signalling the presence of trans-Plutonian planets" 2832: 1202:

published an article corroborating Trujillo and Sheppard's initial findings; proposing a super-Earth (dubbed

31: 27: 7481: 5446: 2391:

Hoyt, William Graves (December 1976). "W. H. Pickering's Planetary Predictions and the Discovery of Pluto".

1404: 950:

in 1992. Since then, thousands of such objects have been discovered. Most are now recognized as part of the

256:, showed that the star had not in fact vanished, and that the previous results had been due to human error. 194:

discovered Neptune, exactly where Le Verrier had predicted. There remained some slight discrepancies in the

7568: 7123: 7103: 6998: 3491: 1384:. It was first proposed in 1999 by astrophysicists John Matese, Patrick Whitman and Daniel Whitmire of the 362: 319: 7486: 6124: 5594: 5098:"Twisted extreme trans-Neptunian orbital parameter space: statistically significant asymmetries confirmed" 4887: 3763: 7643: 7169: 7098: 7063: 6102: 6096: 1369: 556: 296: 2600: 445:, like the giant planets. As a result, it would show a disc with diameter of about one arcsecond and an 284:

planets. These elements accorded suggestively with those made independently by another astronomer named

7793: 7558: 7359: 7242: 7225: 7191: 6123: 6065: 5043: 992: 539: 191: 84: 3254: 2327: 1837: 7401: 7376: 7186: 5966: 4436: 3876: 1741: 1534: 981: 665: 386: 280: 38: 6120: 5097: 1206:) based on a statistical clustering of the arguments of perihelia (noted before) near zero and also 573: 198:' orbits. These were taken to indicate the existence of yet another planet orbiting beyond Neptune. 7692: 7297: 5904: 4437:"Forget Planet 9 - there's evidence of a tenth planet lurking at the edge of the solar system" 4380: 3794: 1870: 988: 810: 601: 4984:"Is the Recently Proposed Mars-Sized Perturber at 65–80 AU Ruled Out by the Cassini Ranging Data?" 2568:. In Baracci, M. Antonietta; Boenhardt, Hermann; Cruikchank, Dale; Morbidelli, Alissandro (eds.). 2034:"Constraints on Planet Nine's Orbit and Sky Position within a Framework of Mean Motion Resonances" 1253:

Additionally, speculation of a possible trans-Neptunian planet has revolved around the so-called "

7381: 7208: 6855: 6759: 6672: 6372: 6222: 6113: 6104: 5817: 5400:

Whitmire, Daniel P. & Matese, John J. (January 1985). "Periodic comet showers and planet X".

4323: 4275: 2262: 1926: 1424: 1187: 1021: 688: 671:

In 1973, based on the similarities in the periodicity and amplitude of brightness variation with

300: 5920: 1662: 1183:" of between 2 and 15 Earth masses beyond 200 AU and possibly on an inclined orbit at 1,500 AU. 7386: 7324: 7272: 7262: 7247: 7198: 7058: 6988: 6410: 6098: 6004: 5930: 5805: 5705: 3525: 1314: 1211: 1169: 1091: 943: 534: 514: 264: 187: 20: 7307: 6118: 6110: 6107: 5925: 3417: 1635: 1628: 1571:

Bower, Ernest Clare (1931). "On the orbit and mass of Pluto with an ephemeris for 1931-1932".

311:

In 1902, after observing the orbits of comets with aphelia beyond Neptune, Theodor Grigull of

7873: 7752: 7679: 7553: 7406: 7369: 7257: 7252: 6058: 955: 458: 190:. On 23 September 1846, the night following his receipt of the letter, Galle and his student 7421: 5320:

Standish, E. M. (May 1993). "Planet X - No dynamical evidence in the optical observations".

5066: 4246:. Lowell Lectures in Astronomy. Boston, MA: Museum of Science, Boston / WGBH. Archived from 4156: 3364:

Standish, E. M. (May 1993). "Planet X - No dynamical evidence in the optical observations".

329:

suggested the existence of two trans-Neptunian planets, which he named after the Hindu gods

7314: 7267: 6924: 6382: 6347: 6342: 6236: 6187: 6160: 6116: 6095: 5899: 5866: 5409: 5362: 5329: 5278: 5170: 5119: 5062: 5005: 4938: 4758: 4530: 4399: 4335: 4152: 4093: 4032: 3971: 3813: 3713: 3623: 3373: 3316: 3269: 3159: 3111: 3039: 2994: 2893: 2855: 2803: 2759: 2685: 2634: 2537: 2516: 2277: 2232: 2191: 2128: 2119:

Sherrill, Thomas J. (February 1999). "A Career of Controversy: The Anomaly of T.J.J. See".

2055: 1889: 1805: 1750: 1580: 1307: 1266: 1013: 828: 681: 657: 637: 623: 518: 338: 326: 214: 161: 6099: 6097: 2561:

Davies, John K.; McFarland, John; Bailey, Mark E.; Marsden, Brian G.; et al. (2008).

1592: 8: 7766: 7655: 7493: 7466: 7416: 7220: 6684: 6377: 6229: 5552: 5525: 4842: 4710: 4269: 3848: 1480: 1113: 977: 840: 832: 628: 437:

locations, Lowell conducted a second search from 1914 to 1916. In 1915, he published his

210: 182: 6580: 6459: 5413: 5366: 5333: 5282: 5174: 5123: 5009: 4942: 4762: 4534: 4403: 4339: 4097: 4036: 3975: 3817: 3717: 3627: 3500: 3446: 3377: 3320: 3273: 3163: 3115: 3043: 2998: 2897: 2859: 2807: 2763: 2689: 2638: 2281: 2236: 2195: 2132: 2059: 1893: 1809: 1754: 1584: 954:, a swarm of icy bodies left over from the Solar System's formation that orbit near the 7843: 7831: 7746: 7616: 7563: 7441: 7411: 7319: 7132: 6269: 6100: 5956: 5951: 5572: 5487: 5433: 5388: 5188: 5160: 5109: 5078: 5052: 5023: 4995: 4964: 4928: 4867: 4774: 4748: 4579: 4548: 4520: 4417: 4389: 4247: 4192: 4168: 4142: 4111: 4083: 4050: 4022: 3989: 3961: 3829: 3825: 3803: 3737: 3703: 3641: 3613: 3233: 3177: 3063: 3029: 2917: 2432: 2416: 2152: 2073: 2045: 2014: 2006: 1907: 1879: 1829: 1766: 1718: 1199: 618: 446: 401: 397: 303:

led two searches for trans-Neptunian planets. The first was begun by Danish astronomer

260: 202: 6553: 6516: 5625: 4688: 4463: 4302: 3410: 1254: 991:

defined both Eris and Pluto not as planets but as dwarf planets because they have not

7606: 7176: 7118: 6909: 6798: 6724: 6665: 6394: 6034: 5961: 5700: 5615: 5425: 5380: 5255: 5236: 5217: 5192: 5082: 4968: 4956: 4599: 4172: 4054: 3993: 3833: 3729: 3636: 3601: 3421: 3334: 3285: 3215: 3181: 3067: 3055: 2952: 2921: 2909: 2873: 2821: 2723: 2652: 2424: 2408: 2359: 2156: 2144: 2077: 2068: 2033: 2018: 1998: 1902: 1865: 1821: 1770: 1710: 1702: 1639: 1596: 1460: 1389: 1223: 1165: 1124: 892: 851: 412:

in the name represents an unknown and is pronounced as the letter, as opposed to the

276: 218: 178: 134: 6636: 5392: 5027: 4778: 4552: 4115: 3645: 3492:

Central Bureau for Astronomical Telegrams, International Astronomical Union (2006).

3412:

The Neptune file: a story of astronomical rivalry and the pioneers of planet hunting

2436: 1762: 1630:

The Neptune file: a story of astronomical rivalry and the pioneers of planet hunting

680:

was not Planet X. In 1976, Dale Cruikshank, Carl Pilcher, and David Morrison of the

83:

and Neptune, speculating that the gravity of a large unseen ninth planet could have

7667: 7471: 7461: 7354: 7329: 6739: 6709: 6560: 6434: 6274: 6139: 6029: 5741: 5610: 5562: 5557: 5497: 5437: 5417: 5370: 5337: 5178: 5127: 5070: 5013: 4946: 4766: 4739: 4589: 4538: 4421: 4407: 4351: 4343: 4160: 4101: 4040: 3979: 3821: 3741: 3721: 3631: 3576: 3381: 3324: 3277: 3167: 3119: 3047: 3002: 2948: 2944: 2901: 2863: 2811: 2767: 2693: 2642: 2400: 2240: 2136: 2063: 1990: 1911: 1897: 1833: 1813: 1758: 1722: 1692: 1588: 1074: 966: 891:

Harrington died in January 1993, without having found Planet X. Six months before,

855: 836: 802: 801:

Pluto's size was finally determined conclusively in 1978, when American astronomer

610: 605: 530: 378: 253: 249: 5074: 4164: 3467: 2882:

Rawlins also took into account Pluto's stellar occultation failure as reported by

19:

This article is about hypothetical planets. For known objects beyond Neptune, see

7538: 7436: 7344: 7235: 7213: 7010: 6954: 6944: 6734: 6714: 6689: 6677: 6631: 6619: 6523: 6506: 6466: 6444: 6439: 5846: 5791: 5620: 5211: 4770: 4623: 3572: 3210: 2717: 1468: 1281: 1270: 1141: 1099: 937: 872: 641: 393: 358: 285: 229: 170: 64: 48: 2985:

Christy, J. W. & Harrington, R. S. (August 1978). "The satellite of Pluto".

7855: 7807: 7522: 7302: 7292: 7230: 7093: 7020: 6981: 6902: 6875: 6729: 6599: 6570: 6548: 6538: 6528: 6481: 6039: 5826: 5720: 5710: 5662: 5652: 5642: 5600: 5518: 5452:. Submission to the National Academy of Sciences Board on Physics and Astronomy 5314: 5303: 4412: 4375: 3930: 2844:"Mass and Position Limits for an Hypothetical Tenth Planet of the Solar System" 2140: 1219: 1207: 632: 522: 422: 346: 206: 144:

In 2014, based on similarities of the orbits of a group of recently discovered

90: 5297: 4216:"New evidence suggests a ninth planet lurking at the edge of the solar system" 3329: 3304: 2868: 2843: 2573: 7867: 7621: 7601: 7181: 6914: 6897: 6718: 6641: 6604: 6575: 6565: 6533: 6511: 6491: 6454: 6427: 6422: 6417: 5984: 5835: 5759: 5677: 5657: 5637: 5502: 5475: 5445:

Jones, R. L.; Brown, M. E.; Abell, P. A.; Becker, A. C.; et al. (2009).

5429: 5384: 5132: 5018: 4983: 4960: 4603: 4594: 4567: 4543: 4502: 3733: 3668: 3338: 3289: 3219: 3059: 2913: 2877: 2825: 2698: 2673: 2656: 2412: 2258: 2148: 2002: 1706: 1600: 1161: 1070: 806: 672: 661: 593: 569: 563:

on photographs dating back to 19 March 1915. The decision to name the object

413: 354: 4951: 4917:"Planet X revamped after the discovery of the Sedna-like object 2012 VP113?" 4916: 4106: 4069: 4045: 4008: 3984: 3949: 2647: 2622: 457:, Peru, showed no evidence for the predicted planet, and British astronomer 7819: 7699: 7685: 7476: 7431: 7088: 6971: 6865: 6805: 6788: 6614: 6592: 6543: 6501: 6486: 6471: 6337: 6296: 6261: 6081: 5989: 5875: 5841: 5715: 5695: 5672: 5667: 5647: 5632: 5605: 5149:"No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects" 4347: 2956: 2787: 2244: 1825: 1714: 1486: 1432: 1428: 1409: 1377: 1095: 1004: 947: 676: 268: 195: 118: 114: 4568:"Past the outer rim, into the unknown: structures beyond the Kuiper Cliff" 4068:

de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (11 October 2017).

1408:

interactions. Some may have escaped the Solar System altogether to become

684:

analysed spectra from Pluto's surface and determined that it must contain

7740: 7734: 7517: 7505: 7500: 7451: 7426: 7396: 7391: 7339: 7334: 7159: 7073: 7032: 6993: 6870: 6701: 6624: 6587: 6476: 6009: 5856: 5725: 5183: 5148: 4666: 4645: 3708: 3618: 3034: 2428: 2092: 1203: 1180: 1145:

Prediction of hypothetical Planet Nine's orbit based on unique clustering

1065: 1046: 959: 951: 546: 382: 304: 289: 149: 68: 4464:"Planet 10? Another Earth-size world may lurk in the outer solar system" 4303:"Planet 10? Another Earth-size world may lurk in the outer solar system" 1817: 7759: 7706: 7446: 7025: 6609: 5851: 5775: 4356: 1981:

Grosser, Morton (June 1964). "The Search for a Planet beyond Neptune".

1540: 1413: 1381: 1341: 1286: 1151: 1037:

of these objects may differ considerably from that proposed by Lowell.

999: 912: 906: 245: 7850: 5095: 4565: 4128: 4067: 4006: 3947: 3305:"Planet X and the stability of resonances in the Neptune-Pluto system" 2513:"NASA's Solar System Exploration: Multimedia: Gallery: Pluto's Symbol" 2420: 2010: 312: 7720: 7713: 7142: 7108: 6939: 6860: 6783: 6778: 6749: 6496: 6449: 6318: 6301: 5421: 5375: 5350: 5269:

Tombaugh, Clyde W. (1946). "The Search for the Ninth Planet, Pluto".

5096:

de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (1 May 2022).

4468: 4307: 4129:

de la Fuente Marcos, C.; de la Fuente Marcos, R. (18 February 2021).

3948:

de la Fuente Marcos, C.; de la Fuente Marcos, R. (1 September 2014).

3853: 2563:"The Early Development of Ideas Concerning the Transneptunian Region" 1697: 1680: 1373: 1352: 1330: 1319: 924: 918: 866:

Although its mission did not involve a search for Planet X, the

560: 504: 350: 100: 26:"Ninth planet" and "Tenth planet" redirect here. For other uses, see 6744: 4711:"NASA's WISE Survey Finds Thousands of New Stars, But No 'Planet X'" 7773: 7611: 7078: 6934: 6919: 6660: 6367: 6215: 5492: 5468: 5341: 5165: 5114: 5057: 4872: 4584: 4441: 4394: 4147: 4088: 4027: 3725: 3385: 3281: 3172: 3147: 3123: 3051: 3006: 2905: 2816: 2791: 2772: 2747: 2404: 2050: 1994: 1884: 1105: 1009: 664:'s measurements of Pluto's diameter with the 200-inch telescope at 588: 454: 429: 106: 5000: 4933: 4865: 4753: 4525: 3966: 3808: 1500:. At this location, it would be approximately 630 AU from the Sun. 858:

around the Sun. However, both Marsden and Planet X proponent

166: 7015: 7003: 6929: 6328: 6306: 6181: 6166: 5999: 5307: 4566:

de La Fuente Marcos, C.; de La Fuente Marcos, R. (October 2023).

4287: 3252: 2719:

Is Pluto a Planet?: A Historical Journey through the Solar System

1262: 685: 366: 342: 138: 56: 3253:

Houck JR, Schneider DP, Danielson GE, et al. (March 1985).

2741: 2739: 1102:

leaving the remaining trans-Neptunian objects on stable orbits.

1031: 7456: 6653: 6648: 6362: 6357: 6323: 6311: 6256: 6208: 6201: 6176: 6171: 6050: 5994: 4007:

de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (2016).

3757:"Searching for Sedna's Sisters: Exploring the inner Oort cloud" 1456: 1427:

in Norse mythology, would be about 12–25 AU distant and have a

1273:

have suggested that an object with a mass between 0.3~0.7

1191: 1025: 1017: 931: 880: 442: 433: 334: 330: 130: 80: 60: 3102:

Harrington, R. S. (October 1988). "The location of Planet X".

1791:"A Sedna-like body with a perihelion of 80 astronomical units" 1269:

and inclined orbit. Computer simulations by Patryk Lykawka of

1179:

and other extremely distant TNOs suggests the existence of a "

1051: 141:-sized (≈318 Earth masses) or larger object out to 26,000 AU. 6773: 6352: 6284: 6279: 6194: 6149: 6144: 5541: 4503:"Is the recently proposed Mars-sized perturber at 65–80 2736: 2572:. University of Arizona Press. pp. 11–23. Archived from 1431:-sized diameter of 220 to 880 km. However, if it were a 1215: 577: 499: 463: 272: 222: 94: 76: 37:"Venkatesh Ketakar" redirects here. For the sociologist, see 4794:"News 02/16/11 Does the Solar System Have Giant New Planet?" 4271:

Pluto, Eris, and the dwarf planets of the outer solar system

2560: 6405: 6289: 6154: 5040: 4715: 3255:"Unidentified IRAS sources - Ultrahigh-luminosity galaxies" 1393: 867: 418: 7814: 5480:

Monthly Notices of the Royal Astronomical Society: Letters

5474:

Raymond, Sean N.; Izidoro, Andre; Kaib, Nathan A. (2023).

4921:

Monthly Notices of the Royal Astronomical Society: Letters

4572:

Monthly Notices of the Royal Astronomical Society: Letters

3954:

Monthly Notices of the Royal Astronomical Society: Letters

3148:"The Effect of a Trans-Plutonian Planet on Halley's Comet" 2270:

Solar System Formation and Evolution ASP Conference Series

2222: 1864:

Batygin, Konstantin; Brown, Michael E. (20 January 2016).

1248: 987:

Eris was never officially classified as a planet, and the

984:

press release described the object as the "tenth planet".

962:, were initially described in the media as "new planets". 600:

astronomers thought that Pluto would be massive enough to

517:, Percival's brother. In 1929 the observatory's director, 453:

period of 373.5 years. Plates taken at his observatory in

381:. For the hypothetical planet first proposed in 2014, see 377:"Planet X" redirects here. For the conspiracy theory, see 205:

reported a conversation he had had with French astronomer

6134: 5102:

Monthly Notices of the Royal Astronomical Society Letters

4892: 4484:"Forget about Planet Nine. Here's evidence for Planet 10" 4075:

Monthly Notices of the Royal Astronomical Society Letters

4014:

Monthly Notices of the Royal Astronomical Society Letters

3931:"A new object at the edge of our Solar System discovered" 2883: 2668: 2666: 1866:"Evidence for a distant giant planet in the Solar system" 1463:, and a Jupiter-sized or larger object out to 26,000 AU. 59:

in 1846, there was considerable speculation that another

5510: 4188:"Ninth Planet May Exist Beyond Pluto, Scientists Report" 4009:"Commensurabilities between ETNOs: a Monte Carlo survey" 2623:"On a Criterion for the Prediction of an Unknown Planet" 345:

and applying them to the outer planets. The three inner

5252:

The hunt for Planet X: new worlds and the fate of Pluto

5213:

Planet quest: the epic discovery of alien solar systems

3693: 3152:

Publications of the Astronomical Society of the Pacific

2968: 2966: 2886:

Publications of the Astronomical Society of the Pacific

2796:

Publications of the Astronomical Society of the Pacific

2752:

Publications of the Astronomical Society of the Pacific

361:, are locked in a complicated 1:2:4 resonance called a 113:(IAU) reclassified Pluto and its largest neighbours as 4880: 2663: 7791: 5444: 2792:"The Photographic Magnitude and Color Index of Pluto" 2480:"Percival Lowell's three early searches for Planet X" 2175:

Chhabra, J. G.; Sharma, S. D.; Khanna, Manju (1984).

521:, summarily handed the job of locating the planet to 5089: 4376:"The curiously warped mean plane of the Kuiper belt" 4274:(academic talk). Smithsonian. Event occurs at 50ᵐ. 3019: 2963: 1439: 640:

of Uranus' longitude using a trigonometric formula,

5463:Andrew Coates provides a simplified summary of the 3440: 3303:Jackson, A. A. & Killen, R. M. (October 1988). 2174: 2031: 1080: 117:, leaving Neptune the farthest known planet in the 5473: 5233:Planets beyond: discovering the outer solar system 4730: 4709:Clavin, Whitney; Harrington, J.D. (7 March 2014). 4619:"Up telescope! Search begins for giant new planet" 4321: 4000: 3409: 2263:"Orbital Resonances and Chaos in the Solar System" 1627: 1448:An analysis of mid-infrared observations with the 5140: 3606:Monthly Notices of the Royal Astronomical Society 3524:. Jet Propulsion Laboratory. 2005. Archived from 3309:Monthly Notices of the Royal Astronomical Society 2984: 2848:Monthly Notices of the Royal Astronomical Society 2678:Monthly Notices of the Royal Astronomical Society 2627:Monthly Notices of the Royal Astronomical Society 942:After the discovery of Pluto and Charon, no more 902:Jet Propulsion Laboratory Developmental Ephemeris 423:canals constructed by an intelligent civilization 87:Uranus enough to account for the irregularities. 7865: 4708: 4213: 3791: 3600:Horner, J. & Evans, N. W. (September 2002). 2841: 2353: 1788: 1678: 1663:"IAU 2006 General Assembly: Resolutions 5 and 6" 1214:. They estimated it to be ten times the mass of 1149:In 2014, astronomers announced the discovery of 1106:Elongated orbits of group of Kuiper belt objects 817: 408:, a name previously used by Gabriel Dallet. The 173:, an early proponent of a trans-Neptunian planet 98:1990s, when a study of measurements made by the 6094: 5235:. The Wiley science editions. New York: Wiley. 4369: 4367: 4214:Achenbach, Joel; Feltman, Rachel (2016-01-20). 3877:"Japanese scientists eye mysterious 'Planet X'" 1784: 1782: 1780: 1679:Tegler, S. C. & Romanishin, W. (May 2001). 1668:. International Astronomical Union. 2006-08-24. 533:, which by exchanging images quickly created a 449:between 12 and 13—bright enough to be spotted. 5399: 4838:"Astronomers Skeptical Over "Planet X" Claims" 4736: 4322:Brunini, A & M.D. Melita (November 2002). 3868: 3787: 3785: 3783: 3522:"NASA-Funded Scientists Discover Tenth Planet" 2032:Millholland, Sarah; Laughlin, Gregory (2017). 1459:-sized object (95 Earth masses) out to 10,000 875:"; none were found to be Solar System bodies. 133:-sized object (95 Earth masses) out to 10,000 6255: 6066: 5526: 4702: 3350: 3348: 3302: 1032:Subsequently proposed trans-Neptunian planets 583: 392:In 1894, with the help of William Pickering, 5271:Astronomical Society of the Pacific Leaflets 4428: 4373: 4364: 4179: 4122: 3840: 3602:"Biases in cometary catalogues and Planet X" 3581:UCLA - Earth, Planetary & Space Sciences 1863: 1859: 1857: 1777: 1734: 1732: 1040: 932:Discovery of further trans-Neptunian objects 559:on March 13, 1930. The new object was later 4975: 4610: 4315: 3780: 3599: 3203: 2722:. Princeton University Press. p. 141. 2303: 2301: 2299: 2297: 2295: 2293: 2291: 2216: 1976: 67:'s quest for Planet X. Lowell proposed the 6073: 6059: 5533: 5519: 4888:"NASA wants you to help find a new planet" 3941: 3657: 3655: 3345: 3101: 2980: 2978: 2170: 2168: 2166: 1974: 1972: 1970: 1968: 1966: 1964: 1962: 1960: 1958: 1956: 1621: 1619: 604:planets. This led them to assume that its 5501: 5491: 5374: 5249: 5182: 5164: 5131: 5113: 5056: 5017: 4999: 4988:Frontiers in Astronomy and Space Sciences 4950: 4932: 4908: 4871: 4752: 4689:"Can WISE Find the Hypothetical 'Tyche'?" 4646:"Astrophysics Homepage of John J. Matese" 4593: 4583: 4559: 4542: 4524: 4513:Frontiers in Astronomy and Space Sciences 4411: 4393: 4355: 4146: 4105: 4087: 4044: 4026: 3983: 3965: 3807: 3707: 3661: 3635: 3617: 3571: 3328: 3171: 3139: 3033: 2867: 2815: 2771: 2715: 2697: 2646: 2477: 2319: 2067: 2049: 1901: 1883: 1854: 1789:Trujillo, C. A.; Sheppard, S. S. (2014). 1729: 1696: 1523:List of hypothetical Solar System objects 1364: 871:were distant galaxies and the tenth was " 16:Hypothetical planets further than Neptune 7586:Interstellar and circumstellar molecules 5319: 5268: 5230: 5209: 4835: 4831: 4829: 4822:Far-out worlds, just waiting to be found 4434: 3874: 3849:"Large 'Planet X' May Lurk Beyond Pluto" 3548:"Unabashedly Onward to the Ninth Planet" 3407: 3363: 2842:Rawlins, D.; Hammerton, M. (June 1973). 2711: 2709: 2556: 2554: 2464: 2462: 2460: 2458: 2456: 2288: 2257: 2118: 2097:The Swedish Amateur Astronomical Society 1625: 1140: 1050: 969:and his team announced the discovery of 850:studied irregularities in the motion of 587: 545: 503: 337:, by reworking the patterns observed by 165: 43: 7884:Hypothetical bodies of the Solar System 7782:) may be read as "within" or "part of". 6810:Planetary orbit-crossing minor planets 5946: 5348: 4861: 4859: 4616: 4509:ruled out by the Cassini ranging data?" 4237: 4235: 3902:"New planet found in our Solar System?" 3754: 3748: 3689: 3687: 3652: 3088: 3086: 2975: 2386: 2384: 2163: 1980: 1953: 1924: 1616: 1566: 1564: 1562: 1503:Using public data on the orbits of the 1218:(about 60% the mass of Neptune) with a 660:, using the same assumptions. In 1949, 177:In the 1840s, the French mathematician 51:, originator of the Planet X hypothesis 7866: 5465:history behind the search & claims 5146: 4686: 4374:Volk, Kathryn; Malhotra, Renu (2017). 2745: 2595: 2593: 2372: 2177:"Prediction of Pluto by V. P. Ketakar" 2114: 2112: 1738: 1168:argued that the orbital clustering of 998:A number of astronomers, most notably 879:regardless of their separation in the 848:Lawrence Livermore National Laboratory 55:Following the discovery of the planet 6054: 5514: 4981: 4914: 4826: 4500: 4267: 4241: 4185: 4061: 3662:Schilling, Govert (11 January 2008). 3545: 3204:O'Toole, Thomas (December 29, 1983). 3145: 2935:"Pluto: Evidence for methane frost". 2786: 2706: 2620: 2551: 2453: 1672: 1657: 1655: 1570: 1518:Fictional planets of the Solar System 1419:In December 2015, astronomers at the 886: 493: 428:Lowell's first search focused on the 7894:Hypothetical trans-Neptunian objects 4856: 4791: 4680: 4232: 3875:Hasegawa, Kyoko (28 February 2008). 3846: 3684: 3083: 3013: 2601:""Planet X" Orbit Raises More Doubt" 2540:. New Mexico Museum of Space History 2390: 2381: 2184:Indian Journal of History of Science 2121:Journal for the History of Astronomy 2090: 1559: 1528: 1455:have ruled out the possibility of a 1386:University of Louisiana at Lafayette 772:Cruikshank, Pilcher, & Morrison 155: 129:have ruled out the possibility of a 5147:Napier, J. K.; et al. (2021). 4617:Rodgers, Paul (February 13, 2011). 3468:"Astronomers discover 'new planet'" 2590: 2325: 2109: 1546:Wide-field Infrared Survey Explorer 1398:Wide-field Infrared Survey Explorer 79:of the giant planets, particularly 13: 6090: 5290: 5254:. New York, NY: Copernicus Books. 4244:"Pluto and the outer solar system" 4186:Chang, Kenneth (20 January 2016). 4135:Astronomy and Astrophysics Letters 2621:Brown, Ernest W. (November 1931). 1652: 809:. This enabled him, together with 439:Memoir of a Trans-Neptunian Planet 396:(a wealthy Bostonian) founded the 14: 7930: 4435:Osbourne, Hannah (23 June 2017). 3546:Stern, Alan (September 8, 2006). 2746:Kuiper, Gerard P. (August 1950). 1925:Burdick, Alan (20 January 2016). 1593:10.5479/ADS/bib/1931LicOB.15.171B 1440:Constraints on additional planets 1133:or detached orbits like Sedna's. 7849: 7837: 7825: 7813: 7801: 7673: 7661: 7649: 6080: 5816: 5810: 5804: 5034: 4242:Brown, Michael (11 April 2007). 3637:10.1046/j.1365-8711.2002.05649.x 1081:Excitement of Kuiper belt orbits 1059: 111:International Astronomical Union 105:its neighbours should, like the 7549:Gravitationally rounded objects 5349:Quinlan, Gerald D. (May 1993). 5203: 4811: 4785: 4659: 4648:. Ucs.louisiana.edu. 2011-09-21 4638: 4494: 4476: 4456: 4295: 4278:from the original on 2021-11-14 4261: 4207: 3923: 3894: 3593: 3577:"Dave Jewitt: Planets IX and X" 3565: 3539: 3514: 3485: 3460: 3434: 3401: 3392: 3357: 3296: 3246: 3197: 3188: 3130: 3095: 3074: 2928: 2780: 2614: 2570:The Solar System Beyond Neptune 2530: 2505: 2496: 2478:Schindler, Kevin (2015-05-14). 2471: 2444: 2347: 2338: 2310: 2251: 2084: 2025: 1944: 1535:Large Synoptic Survey Telescope 1505:extreme trans-Neptunian objects 1198:On January 20, 2016, Brown and 432:, the plane encompassed by the 341:in the planetary satellites of 242:United States Naval Observatory 146:extreme trans-Neptunian objects 4687:Clavin, Whitney (2011-02-18). 3664:"The mystery of Planet X" 3206:"Possibly as Large as Jupiter" 2949:10.1126/science.194.4267.835-a 1918: 1607: 1421:Atacama Large Millimeter Array 1376:proposed to be located in the 1229: 1136: 550:Discovery photographs of Pluto 240:, Assistant Astronomer at the 1: 7909:Solar System dynamic theories 7083: 5153:The Planetary Science Journal 3755:Schwamb, Megan (2007-09-18). 2684:(4): 380–385. February 1931. 1552: 1425:fast-moving messenger goddess 1249:Kuiper cliff and "Planet Ten" 846:In 1972, Joseph Brady of the 818:Further searches for Planet X 32:Tenth planet (disambiguation) 28:Ninth planet (disambiguation) 7899:Early scientific cosmologies 4820:, 23 July 2005, issue 2509, 4771:10.1016/j.icarus.2010.11.009 3826:10.1088/0004-6256/135/4/1161 3441:Minor Planet Center (1992). 3416:. New York: Walker. p. 2716:Weintraub, David A. (2014). 1634:. New York: Walker. p. 1613:Tombaugh (1946), p. 73. 1317:(120 AU) or well beyond it ( 993:cleared their neighbourhoods 644:asserted (in agreement with 320:Thomas Jefferson Jackson See 7: 7919:Planets of the Solar System 7644:Outline of the Solar System 7407:Interplanetary medium/space 5075:10.1051/0004-6361/201628227 4268:Brown, Mike (August 2008). 4165:10.1051/0004-6361/202140311 3136:Croswell (1997), pp. 62–63. 3080:Croswell (1997), pp. 57–58. 2468:Croswell (1997), pp. 32–55. 1511: 1186:In 2014 astronomers at the 557:Harvard College Observatory 490:; none were ever detected. 372: 325:In 1911, Indian astronomer 297:Harvard College Observatory 10: 7935: 7879:Astronomical controversies 7360:Extraterrestrial materials 5351:"Planet X: A Myth Exposed" 5250:Schilling, Govert (2009). 5044:Astronomy and Astrophysics 3847:Than, Ker (18 June 2008). 3238:: CS1 maint: url-status ( 2326:Ley, Willy (August 1956). 2141:10.1177/002182869903000102 2069:10.3847/1538-3881/153/3/91 1903:10.3847/0004-6256/151/2/22 1573:Lick Observatory Bulletins 1222:of approximately 400–1500 1044: 938:History of the Kuiper belt 935: 584:Pluto loses Planet X title 580:, but no further planets. 540:apparent retrograde motion 497: 376: 367:2:3 resonance with Neptune 159: 36: 25: 18: 7680:Earth sciences portal 7639: 7594: 7531: 7402:Interplanetary dust cloud 7281: 7117: 7047: 6758: 6700: 6393: 6246: 6088: 6022: 5977: 5939: 5913: 5892: 5885: 5865: 5825: 5802: 5784: 5768: 5750: 5734: 5686: 5586: 5571: 5548: 5540: 5476:"Oort cloud (Exo)planets" 5306:. 2016-02-17 – via 3762:. Caltech. Archived from 3696:The Astrophysical Journal 3262:The Astrophysical Journal 3146:Brady, Joseph L. (1972). 2354:Govert Schilling (2009). 1927:"Discovering Planet Nine" 1763:10.1088/0004-637X/781/1/4 1742:The Astrophysical Journal 1474:Using modern data on the 1469:Backyard Worlds: Planet 9 1210:near 113° of six distant 1041:Orbits of distant objects 989:2006 definition of planet 982:Jet Propulsion Laboratory 783:Christy & Harrington 706:Mass estimates for Pluto 666:Mount Palomar Observatory 387:Planet X (disambiguation) 39:Shridhar Venkatesh Ketkar 7693:Local Interstellar Cloud 6411:other near-Earth objects 5905:IAU definition of planet 5322:The Astronomical Journal 5216:. New York: Free Press. 5019:10.3389/fspas.2017.00028 4544:10.3389/fspas.2017.00028 4413:10.3847/1538-3881/aa79ff 4381:The Astronomical Journal 3795:The Astronomical Journal 3366:The Astronomical Journal 3104:The Astronomical Journal 3022:The Astronomical Journal 2987:The Astronomical Journal 2674:"The Discovery of Pluto" 2358:. Springer. p. 34. 2330:. For Your Information. 2038:The Astronomical Journal 1871:The Astronomical Journal 1471:citizen science project. 946:(TNOs) were found until 811:Robert Sutton Harrington 69:Planet X hypothesis 7914:Trans-Neptunian objects 7656:Solar System portal 7382:Giant-impact hypothesis 6989:Trans-Neptunian objects 5231:Littmann, Mark (1990). 5067:2016A&A...587L...8F 4982:Iorio, Lorenzo (2017). 4798:The Norwalk Daily Voice 4501:Iorio, Lorenzo (2017). 4157:2021A&A...646L..14D 3398:Littman (1990), p. 204. 3354:Croswell (1997), p. 66. 3330:10.1093/mnras/235.2.593 3194:Croswell (1997), p. 63. 2972:Croswell (1997), p. 57. 2943:(4267): 835–837. 1976. 2869:10.1093/mnras/162.3.261 2748:"The Diameter of Pluto" 2450:Croswell (1997), p. 49. 2328:"The Demotion of Pluto" 2316:Croswell (1997), p. 43. 1403:The oligarch theory of 1212:trans-Neptunian objects 1188:Universidad Complutense 1092:trans-Neptunian objects 944:trans-Neptunian objects 728:Nicholson & Mayall 301:William Henry Pickering 7544:Possible dwarf planets 7387:Gravitational collapse 7325:Circumstellar envelope 6130: 6005:Trans-Neptunian object 5706:Coleta de Dados Colles 5503:10.1093/mnrasl/slad079 5210:Croswell, Ken (1997). 5133:10.1093/mnrasl/slac012 4836:Billings, Lee (2015). 4595:10.1093/mnrasl/slad132 4348:10.1006/icar.2002.6935 3908:. 2012. Archived from 3881:BibliotecaPleyades.net 3408:Standage, Tom (2000). 2699:10.1093/mnras/91.4.380 2515:. NASA. Archived from 2502:Tombaugh (1946), p. 79 2344:Littman (1990), p. 70. 2332:Galaxy Science Fiction 2245:10.1006/icar.2002.6939 2093:"Hypothetical Planets" 1950:Croswell (1997), p. 43 1626:Standage, Tom (2000). 1365:Other proposed planets 1242: 1170:arguments of perihelia 1146: 1056: 596: 551: 515:Abbott Lawrence Lowell 509: 508:Clyde William Tombaugh 385:. For other uses, see 263:noted that the comets 188:Johann Gottfried Galle 174: 73:apparent discrepancies 52: 21:Trans-Neptunian object 7753:Laniakea Supercluster 7370:Sample-return mission 6129: 5299:Planet X Discovered?? 4952:10.1093/mnrasl/slu116 4107:10.1093/mnrasl/slx106 4046:10.1093/mnrasl/slw077 3985:10.1093/mnrasl/slu084 2648:10.1093/mnras/92.1.80 2356:The Hunt For Planet X 1410:free-floating planets 1237: 1144: 1054: 1002:, the head of NASA's 860:P. Kenneth Seidelmann 791:0.00218 (1/459 Earth) 591: 549: 507: 169: 47: 7889:Hypothetical planets 7668:Astronomy portal 7569:Solar System objects 7315:Circumplanetary disk 5900:Definition of planet 5893:Official definitions 5663:Tombaugh "The Heart" 4667:"Daniel P. Whitmire" 1476:anomalous precession 965:In 2005, astronomer 805:discovered its moon 682:University of Hawaii 658:US Naval Observatory 519:Vesto Melvin Slipher 339:Pierre-Simon Laplace 327:Venkatesh P. Ketakar 215:Peter Andreas Hansen 162:Discovery of Neptune 7767:Observable universe 7564:Solar System models 7494:Protoplanetary disk 7417:Interstellar medium 7377:Frost/Ice/Snow line 5931:Neil deGrasse Tyson 5414:1985Natur.313...36W 5367:1993Natur.363...18Q 5334:1993AJ....105.2000S 5283:1946ASPL....5...73T 5175:2021PSJ.....2...59N 5124:2022MNRAS.512L...6D 5010:2017FrASS...4...28I 4943:2014MNRAS.444L..78I 4843:Scientific American 4763:2011Icar..211..926M 4669:. Ucs.louisiana.edu 4535:2017FrASS...4...28I 4404:2017AJ....154...62V 4340:2002Icar..160...32B 4220:The Washington Post 4098:2017MNRAS.471L..61D 4037:2016MNRAS.460L..64D 3976:2014MNRAS.443L..59D 3906:National Geographic 3818:2008AJ....135.1161L 3718:2004ApJ...617..645B 3628:2002MNRAS.335..641H 3503:on February 5, 2007 3494:"Circular No. 8747" 3443:"Circular No. 5611" 3378:1993AJ....105.2000S 3321:1988MNRAS.235..593J 3274:1985ApJ...290L...5H 3164:1972PASP...84..314B 3116:1988AJ.....96.1476H 3092:Croswell, pp. 56–71 3044:2006AJ....132..290B 2999:1978AJ.....83.1005C 2898:1966PASP...78..113H 2860:1973MNRAS.162..261R 2808:1934PASP...46..218B 2764:1950PASP...62..133K 2690:1931MNRAS..91..380. 2639:1931MNRAS..92...80B 2538:"Clyde W. Tombaugh" 2282:1998ASPC..149...37M 2237:2002Icar..159..500M 2196:1984InJHS..19...18C 2133:1999JHA....30...25S 2060:2017AJ....153...91M 1894:2016AJ....151...22B 1818:10.1038/nature13156 1810:2014Natur.507..471T 1755:2014ApJ...781....4L 1585:1931LicOB..15..171B 1372:was a hypothetical 1096:Neptune's migration 895:had used data from 873:interstellar cirrus 841:Minor Planet Center 780:0.002 (1/500 Earth) 707: 629:Harvard Observatory 592:Discovery image of 219:Seeberg Observatory 211:George Biddell Airy 183:Newtonian mechanics 7904:Pluto's planethood 7747:Virgo Supercluster 7728:Milky Way subgroup 7559:Natural satellites 7442:Nebular hypothesis 7422:Interstellar space 7412:Interstellar cloud 7320:Circumstellar disc 6910:Near-Earth objects 6794:names and meanings 6131: 5952:Lowell Observatory 5914:Scientist opinions 5184:10.3847/PSJ/abe53e 4915:Iorio, L. (2014). 4896:. 16 February 2017 4193:The New York Times 2608:The New York Times 2484:Astronomy Magazine 1390:long-period comets 1284:such as Sedna and 1200:Konstantin Batygin 1147: 1057: 887:Planet X disproved 769:0.01 (1/100 Earth) 758:0.025 (1/40 Earth) 705: 701: Earth mass. 624:Armin O. Leuschner 619:The New York Times 597: 552: 510: 494:Discovery of Pluto 447:apparent magnitude 402:Flagstaff, Arizona 398:Lowell Observatory 295:In 1900 and 1901, 275:of 47 and 49 261:Camille Flammarion 248:, director of the 217:, director of the 203:Thomas John Hussey 175: 53: 7789: 7788: 7634: 7633: 7630: 7629: 7607:Lagrangian points 7579:by discovery date 7177:Human spaceflight 7148:historical models 7041: 7040: 6666:S/2015 (136472) 1 6048: 6047: 6018: 6017: 5800: 5799: 5701:Challenger Colles 5261:978-0-387-77804-4 5242:978-0-471-51053-6 5223:978-0-684-83252-4 3427:978-0-8027-1363-6 2729:978-1-4008-5297-0 2610:. April 14, 1930. 2334:. pp. 79–91. 1804:(7493): 471–474. 1691:(6836): 423–424. 1681:"Almost Planet X" 1645:978-0-8027-1363-6 1529:Survey telescopes 893:E. Myles Standish 798: 797: 576:, as well as two 363:Laplace resonance 192:Heinrich d'Arrest 179:Urbain Le Verrier 156:Early speculation 7926: 7854: 7853: 7842: 7841: 7840: 7830: 7829: 7828: 7818: 7817: 7806: 7805: 7797: 7783: 7781: 7772: 7765: 7758: 7751: 7745: 7739: 7733: 7726: 7719: 7712: 7705: 7698: 7691: 7678: 7677: 7676: 7666: 7665: 7664: 7654: 7653: 7652: 7355:Exozodiacal dust 7045: 7044: 7011:Detached objects 6253: 6252: 6249: 6248: 6093: 6075: 6068: 6061: 6052: 6051: 5926:Michael E. Brown 5890: 5889: 5820: 5814: 5808: 5742:Sputnik Planitia 5584: 5583: 5535: 5528: 5521: 5512: 5511: 5507: 5505: 5495: 5460: 5458: 5457: 5451: 5441: 5422:10.1038/313036a0 5396: 5378: 5376:10.1038/363018b0 5345: 5315:SEDS on Planet X 5311: 5286: 5265: 5246: 5227: 5197: 5196: 5186: 5168: 5144: 5138: 5137: 5135: 5117: 5093: 5087: 5086: 5060: 5038: 5032: 5031: 5021: 5003: 4979: 4973: 4972: 4954: 4936: 4912: 4906: 4905: 4903: 4901: 4884: 4878: 4877: 4875: 4863: 4854: 4853: 4851: 4850: 4833: 4824: 4815: 4809: 4808: 4806: 4804: 4792:Helhoski, Anna. 4789: 4783: 4782: 4756: 4734: 4728: 4727: 4725: 4723: 4706: 4700: 4699: 4697: 4696: 4684: 4678: 4677: 4675: 4674: 4663: 4657: 4656: 4654: 4653: 4642: 4636: 4635: 4633: 4631: 4614: 4608: 4607: 4597: 4587: 4578:(1): L110–L114. 4563: 4557: 4556: 4546: 4528: 4508: 4507: 4498: 4492: 4491: 4480: 4474: 4473: 4460: 4454: 4453: 4451: 4449: 4432: 4426: 4425: 4415: 4397: 4371: 4362: 4361: 4359: 4319: 4313: 4312: 4299: 4293: 4291: 4285: 4283: 4265: 4259: 4258: 4256: 4255: 4239: 4230: 4229: 4227: 4226: 4211: 4205: 4204: 4202: 4200: 4183: 4177: 4176: 4150: 4126: 4120: 4119: 4109: 4091: 4065: 4059: 4058: 4048: 4030: 4004: 3998: 3997: 3987: 3969: 3945: 3939: 3938: 3937:. 26 March 2014. 3927: 3921: 3920: 3918: 3917: 3898: 3892: 3891: 3889: 3887: 3872: 3866: 3865: 3863: 3861: 3844: 3838: 3837: 3811: 3802:(4): 1161–1200. 3789: 3778: 3777: 3775: 3774: 3768: 3761: 3752: 3746: 3745: 3711: 3709:astro-ph/0404456 3691: 3682: 3681: 3679: 3677: 3672:. pp. 30–33 3659: 3650: 3649: 3639: 3621: 3619:astro-ph/0205150 3597: 3591: 3590: 3588: 3587: 3573:C. Jewitt, David 3569: 3563: 3562: 3560: 3559: 3543: 3537: 3536: 3534: 3533: 3518: 3512: 3511: 3509: 3508: 3499:. Archived from 3498: 3489: 3483: 3482: 3480: 3479: 3464: 3458: 3457: 3455: 3454: 3445:. Archived from 3438: 3432: 3431: 3415: 3405: 3399: 3396: 3390: 3389: 3361: 3355: 3352: 3343: 3342: 3332: 3300: 3294: 3293: 3259: 3250: 3244: 3243: 3237: 3229: 3227: 3226: 3201: 3195: 3192: 3186: 3185: 3175: 3158:(498): 314–322. 3143: 3137: 3134: 3128: 3127: 3099: 3093: 3090: 3081: 3078: 3072: 3071: 3037: 3035:astro-ph/0512491 3017: 3011: 3010: 2982: 2973: 2970: 2961: 2960: 2932: 2926: 2925: 2881: 2871: 2839: 2830: 2829: 2819: 2784: 2778: 2777: 2775: 2758:(366): 133–137. 2743: 2734: 2733: 2713: 2704: 2703: 2701: 2670: 2661: 2660: 2650: 2618: 2612: 2611: 2605: 2597: 2588: 2587: 2585: 2584: 2578: 2567: 2558: 2549: 2548: 2546: 2545: 2534: 2528: 2527: 2525: 2524: 2509: 2503: 2500: 2494: 2493: 2491: 2490: 2475: 2469: 2466: 2451: 2448: 2442: 2440: 2388: 2379: 2376: 2370: 2369: 2351: 2345: 2342: 2336: 2335: 2323: 2317: 2314: 2308: 2307:Tombaugh (1946). 2305: 2286: 2285: 2267: 2255: 2249: 2248: 2220: 2214: 2213: 2211: 2210: 2204: 2198:. Archived from 2181: 2172: 2161: 2160: 2116: 2107: 2106: 2104: 2103: 2091:Schlyter, Paul. 2088: 2082: 2081: 2071: 2053: 2029: 2023: 2022: 1978: 1951: 1948: 1942: 1941: 1939: 1937: 1922: 1916: 1915: 1905: 1887: 1861: 1852: 1851: 1849: 1848: 1842: 1836:. Archived from 1795: 1786: 1775: 1774: 1736: 1727: 1726: 1700: 1698:10.1038/35078164 1676: 1670: 1669: 1667: 1659: 1650: 1649: 1633: 1623: 1614: 1611: 1605: 1604: 1579:(437): 171–178. 1568: 1499: 1498: 1497: 1405:planet formation 1360: 1358: 1357: 1349: 1347: 1346: 1338: 1336: 1335: 1327: 1325: 1324: 1294: 1292: 1291: 1282:detached objects 1178: 1159: 1157: 1156: 1132: 1130: 1129: 1121: 1119: 1118: 1114:(308933) 2006 SQ 1088: 1075:planetary system 975: 856:retrograde orbit 837:Brian G. Marsden 803:James W. Christy 747:0.1 (1/10 Earth) 708: 704: 700: 699: 695: 531:blink comparator 379:Nibiru cataclysm 250:Hamilton College 93:'s discovery of 7934: 7933: 7929: 7928: 7927: 7925: 7924: 7923: 7864: 7863: 7860: 7848: 7838: 7836: 7826: 7824: 7812: 7800: 7792: 7790: 7785: 7779: 7777: 7776: 7770: 7763: 7756: 7749: 7743: 7737: 7731: 7724: 7717: 7710: 7703: 7696: 7689: 7674: 7672: 7662: 7660: 7650: 7648: 7635: 7626: 7590: 7527: 7511:vs. Hill sphere 7437:Molecular cloud 7365:Sample curation 7345:Detached object 7284: 7277: 7121: 7113: 7050: 7037: 6982:Neptune trojans 6765: 6763: 6761: 6754: 6696: 6389: 6260: 6242: 6128: 6091: 6084: 6079: 6049: 6044: 6014: 5973: 5957:Percival Lowell 5935: 5909: 5881: 5861: 5821: 5815: 5809: 5796: 5780: 5764: 5752: 5746: 5730: 5688: 5682: 5575: 5567: 5544: 5539: 5455: 5453: 5449: 5408:(5997): 36–38. 5296: 5293: 5291:Further reading 5262: 5243: 5224: 5206: 5201: 5200: 5145: 5141: 5094: 5090: 5039: 5035: 4980: 4976: 4913: 4909: 4899: 4897: 4886: 4885: 4881: 4864: 4857: 4848: 4846: 4834: 4827: 4816: 4812: 4802: 4800: 4790: 4786: 4735: 4731: 4721: 4719: 4707: 4703: 4694: 4692: 4685: 4681: 4672: 4670: 4665: 4664: 4660: 4651: 4649: 4644: 4643: 4639: 4629: 4627: 4624:The Independent 4615: 4611: 4564: 4560: 4505: 4504: 4499: 4495: 4488:www.science.org 4482: 4481: 4477: 4472:. 22 June 2017. 4462: 4461: 4457: 4447: 4445: 4433: 4429: 4372: 4365: 4320: 4316: 4311:. 22 June 2017. 4301: 4300: 4296: 4281: 4279: 4266: 4262: 4253: 4251: 4240: 4233: 4224: 4222: 4212: 4208: 4198: 4196: 4184: 4180: 4127: 4123: 4066: 4062: 4005: 4001: 3946: 3942: 3929: 3928: 3924: 3915: 3913: 3912:on May 14, 2012 3900: 3899: 3895: 3885: 3883: 3873: 3869: 3859: 3857: 3845: 3841: 3790: 3781: 3772: 3770: 3766: 3759: 3753: 3749: 3692: 3685: 3675: 3673: 3660: 3653: 3598: 3594: 3585: 3583: 3570: 3566: 3557: 3555: 3544: 3540: 3531: 3529: 3520: 3519: 3515: 3506: 3504: 3496: 3490: 3486: 3477: 3475: 3466: 3465: 3461: 3452: 3450: 3439: 3435: 3428: 3406: 3402: 3397: 3393: 3362: 3358: 3353: 3346: 3301: 3297: 3257: 3251: 3247: 3231: 3230: 3224: 3222: 3211:Washington Post 3202: 3198: 3193: 3189: 3144: 3140: 3135: 3131: 3100: 3096: 3091: 3084: 3079: 3075: 3018: 3014: 2983: 2976: 2971: 2964: 2934: 2933: 2929: 2840: 2833: 2785: 2781: 2744: 2737: 2730: 2714: 2707: 2672: 2671: 2664: 2619: 2615: 2603: 2599: 2598: 2591: 2582: 2580: 2576: 2565: 2559: 2552: 2543: 2541: 2536: 2535: 2531: 2522: 2520: 2511: 2510: 2506: 2501: 2497: 2488: 2486: 2476: 2472: 2467: 2454: 2449: 2445: 2389: 2382: 2377: 2373: 2366: 2352: 2348: 2343: 2339: 2324: 2320: 2315: 2311: 2306: 2289: 2265: 2256: 2252: 2221: 2217: 2208: 2206: 2202: 2179: 2173: 2164: 2117: 2110: 2101: 2099: 2089: 2085: 2030: 2026: 1979: 1954: 1949: 1945: 1935: 1933: 1923: 1919: 1862: 1855: 1846: 1844: 1840: 1793: 1787: 1778: 1737: 1730: 1677: 1673: 1665: 1661: 1660: 1653: 1646: 1624: 1617: 1612: 1608: 1569: 1560: 1555: 1531: 1514: 1495: 1493: 1492: 1490: 1442: 1367: 1355: 1354: 1351: 1344: 1343: 1340: 1333: 1332: 1329: 1322: 1321: 1318: 1305: 1302: 1289: 1288: 1285: 1279: 1276: 1271:Kobe University 1251: 1232: 1208:ascending nodes 1177: 1173: 1154: 1153: 1150: 1139: 1127: 1126: 1125:(87269) 2000 OO 1123: 1116: 1115: 1112: 1108: 1100:Kozai mechanism 1086: 1083: 1062: 1049: 1043: 1034: 974: 970: 940: 934: 889: 831:, and strongly 820: 799: 697: 693: 692: 642:Ernest W. Brown 586: 502: 496: 394:Percival Lowell 390: 375: 286:David Peck Todd 252:Observatory in 230:Jacques Babinet 171:Jacques Babinet 164: 158: 65:Percival Lowell 49:Percival Lowell 42: 35: 24: 17: 12: 11: 5: 7932: 7922: 7921: 7916: 7911: 7906: 7901: 7896: 7891: 7886: 7881: 7876: 7859: 7858: 7846: 7834: 7822: 7810: 7787: 7786: 7683: 7682: 7670: 7658: 7646: 7640: 7637: 7636: 7632: 7631: 7628: 7627: 7625: 7624: 7619: 7614: 7609: 7604: 7598: 7596: 7592: 7591: 7589: 7588: 7583: 7582: 7581: 7576: 7566: 7561: 7556: 7551: 7546: 7541: 7535: 7533: 7529: 7528: 7526: 7525: 7523:Scattered disc 7520: 7515: 7514: 7513: 7503: 7498: 7497: 7496: 7491: 7490: 7489: 7479: 7474: 7469: 7464: 7454: 7449: 7444: 7439: 7434: 7429: 7424: 7419: 7414: 7409: 7404: 7399: 7394: 7389: 7384: 7379: 7374: 7373: 7372: 7367: 7357: 7352: 7347: 7342: 7337: 7332: 7327: 7322: 7317: 7312: 7311: 7310: 7308:Excretion disk 7303:Accretion disk 7300: 7295: 7293:Star formation 7289: 7287: 7279: 7278: 7276: 7275: 7270: 7265: 7260: 7255: 7250: 7245: 7240: 7239: 7238: 7228: 7223: 7218: 7217: 7216: 7206: 7201: 7196: 7195: 7194: 7189: 7184: 7182:space stations 7174: 7173: 7172: 7167: 7157: 7156: 7155: 7150: 7145: 7135: 7129: 7127: 7115: 7114: 7112: 7111: 7106: 7101: 7096: 7091: 7086: 7081: 7076: 7071: 7066: 7061: 7055: 7053: 7042: 7039: 7038: 7036: 7035: 7030: 7029: 7028: 7023: 7021:Scattered disc 7018: 7013: 7008: 7007: 7006: 7001: 6986: 6985: 6984: 6979: 6969: 6968: 6967: 6962: 6957: 6952: 6947: 6942: 6937: 6932: 6927: 6917: 6912: 6907: 6906: 6905: 6900: 6895: 6890: 6889: 6888: 6883: 6873: 6868: 6863: 6853: 6852: 6851: 6846: 6841: 6836: 6831: 6826: 6821: 6816: 6808: 6803: 6802: 6801: 6796: 6786: 6781: 6776: 6770: 6768: 6756: 6755: 6753: 6752: 6747: 6742: 6737: 6732: 6727: 6722: 6712: 6706: 6704: 6698: 6697: 6695: 6694: 6693: 6692: 6682: 6681: 6680: 6670: 6669: 6668: 6658: 6657: 6656: 6646: 6645: 6644: 6639: 6629: 6628: 6627: 6622: 6617: 6612: 6607: 6597: 6596: 6595: 6585: 6584: 6583: 6578: 6573: 6568: 6558: 6557: 6556: 6551: 6546: 6541: 6536: 6531: 6521: 6520: 6519: 6514: 6509: 6504: 6499: 6494: 6489: 6484: 6479: 6474: 6464: 6463: 6462: 6457: 6452: 6447: 6442: 6432: 6431: 6430: 6425: 6415: 6414: 6413: 6408: 6399: 6397: 6391: 6390: 6388: 6387: 6386: 6385: 6380: 6375: 6370: 6365: 6360: 6355: 6350: 6345: 6335: 6334: 6333: 6332: 6331: 6326: 6316: 6315: 6314: 6309: 6294: 6293: 6292: 6287: 6282: 6277: 6266: 6264: 6247: 6244: 6243: 6241: 6240: 6233: 6226: 6219: 6212: 6205: 6198: 6191: 6184: 6179: 6174: 6169: 6164: 6157: 6152: 6147: 6142: 6137: 6089: 6086: 6085: 6078: 6077: 6070: 6063: 6055: 6046: 6045: 6043: 6042: 6040:Venetia Burney 6037: 6032: 6026: 6024: 6020: 6019: 6016: 6015: 6013: 6012: 6007: 6002: 5997: 5992: 5987: 5981: 5979: 5975: 5974: 5972: 5971: 5970: 5969: 5964: 5962:Clyde Tombaugh 5959: 5949: 5943: 5941: 5937: 5936: 5934: 5933: 5928: 5923: 5917: 5915: 5911: 5910: 5908: 5907: 5902: 5896: 5894: 5887: 5883: 5882: 5880: 5879: 5871: 5869: 5863: 5862: 5860: 5859: 5854: 5849: 5844: 5839: 5831: 5829: 5823: 5822: 5803: 5801: 5798: 5797: 5795: 5794: 5788: 5786: 5782: 5781: 5779: 5778: 5772: 5770: 5766: 5765: 5763: 5762: 5756: 5754: 5748: 5747: 5745: 5744: 5738: 5736: 5732: 5731: 5729: 5728: 5723: 5721:Tenzing Montes 5718: 5713: 5711:Hillary Montes 5708: 5703: 5698: 5692: 5690: 5684: 5683: 5681: 5680: 5675: 5670: 5665: 5660: 5655: 5650: 5645: 5640: 5635: 5630: 5629: 5628: 5626:Meng-pʻo 5623: 5618: 5613: 5608: 5603: 5595:Brass Knuckles 5590: 5588: 5581: 5569: 5568: 5566: 5565: 5560: 5555: 5549: 5546: 5545: 5538: 5537: 5530: 5523: 5515: 5509: 5508: 5471: 5461: 5442: 5397: 5346: 5342:10.1086/116575 5317: 5312: 5304:PBS Space Time 5292: 5289: 5288: 5287: 5277:(209): 73–80. 5266: 5260: 5247: 5241: 5228: 5222: 5205: 5202: 5199: 5198: 5139: 5088: 5033: 4974: 4927:(1): L78–L79. 4907: 4879: 4855: 4825: 4810: 4784: 4747:(2): 926–938. 4729: 4701: 4679: 4658: 4637: 4609: 4558: 4493: 4475: 4455: 4427: 4363: 4314: 4294: 4260: 4231: 4206: 4178: 4141:: L14 (9 pp). 4121: 4082:(1): L61–L65. 4060: 4021:(1): L64–L68. 3999: 3960:(1): L59–L63. 3940: 3922: 3893: 3867: 3839: 3779: 3747: 3726:10.1086/422095 3702:(1): 645–649. 3683: 3651: 3612:(3): 641–654. 3592: 3564: 3552:SpaceDaily.com 3538: 3513: 3484: 3459: 3449:on May 4, 2008 3433: 3426: 3400: 3391: 3386:10.1086/116575 3356: 3344: 3315:(2): 593–601. 3295: 3282:10.1086/184431 3245: 3196: 3187: 3173:10.1086/129290 3138: 3129: 3124:10.1086/114898 3094: 3082: 3073: 3052:10.1086/504422 3028:(1): 290–298. 3012: 3007:10.1086/112284 2974: 2962: 2927: 2906:10.1086/128307 2854:(3): 261–270. 2831: 2817:10.1086/124467 2779: 2773:10.1086/126255 2735: 2728: 2705: 2662: 2613: 2589: 2550: 2529: 2504: 2495: 2470: 2452: 2443: 2405:10.1086/351668 2399:(4): 551–564. 2380: 2378:Croswell p. 50 2371: 2365:978-0387778044 2364: 2346: 2337: 2318: 2309: 2287: 2259:Malhotra, Renu 2250: 2231:(2): 500–504. 2215: 2162: 2108: 2083: 2024: 1995:10.1086/349825 1989:(2): 163–183. 1952: 1943: 1931:The New Yorker 1917: 1853: 1776: 1728: 1671: 1651: 1644: 1615: 1606: 1557: 1556: 1554: 1551: 1550: 1549: 1543: 1538: 1530: 1527: 1526: 1525: 1520: 1513: 1510: 1509: 1508: 1501: 1472: 1441: 1438: 1366: 1363: 1310:ranging data. 1303: 1300: 1277: 1274: 1250: 1247: 1231: 1228: 1220:semimajor axis 1175: 1138: 1135: 1107: 1104: 1082: 1079: 1071:galactic tides 1061: 1058: 1042: 1039: 1033: 1030: 972: 956:ecliptic plane 933: 930: 888: 885: 852:Halley's Comet 819: 816: 796: 795: 792: 789: 785: 784: 781: 778: 774: 773: 770: 767: 763: 762: 759: 756: 752: 751: 748: 745: 741: 740: 737: 734: 730: 729: 726: 723: 719: 718: 715: 712: 703: 654:Lloyd R. Wylie 633:Harlow Shapley 585: 582: 570:variable stars 523:Clyde Tombaugh 498:Main article: 495: 492: 374: 371: 347:Galilean moons 238:James Ferguson 207:Alexis Bouvard 157: 154: 127:WISE telescope 91:Clyde Tombaugh 15: 9: 6: 4: 3: 2: 7931: 7920: 7917: 7915: 7912: 7910: 7907: 7905: 7902: 7900: 7897: 7895: 7892: 7890: 7887: 7885: 7882: 7880: 7877: 7875: 7872: 7871: 7869: 7862: 7857: 7852: 7847: 7845: 7835: 7833: 7823: 7821: 7816: 7811: 7809: 7804: 7799: 7798: 7795: 7784: 7775: 7768: 7761: 7754: 7748: 7742: 7736: 7729: 7722: 7715: 7708: 7701: 7694: 7687: 7681: 7671: 7669: 7659: 7657: 7647: 7645: 7642: 7641: 7638: 7623: 7622:Tidal locking 7620: 7618: 7615: 7613: 7610: 7608: 7605: 7603: 7602:Double planet 7600: 7599: 7597: 7593: 7587: 7584: 7580: 7577: 7575: 7572: 7571: 7570: 7567: 7565: 7562: 7560: 7557: 7555: 7554:Minor planets 7552: 7550: 7547: 7545: 7542: 7540: 7537: 7536: 7534: 7530: 7524: 7521: 7519: 7516: 7512: 7509: 7508: 7507: 7504: 7502: 7499: 7495: 7492: 7488: 7487:Merging stars 7485: 7484: 7483: 7480: 7478: 7475: 7473: 7470: 7468: 7465: 7463: 7460: 7459: 7458: 7455: 7453: 7450: 7448: 7445: 7443: 7440: 7438: 7435: 7433: 7430: 7428: 7425: 7423: 7420: 7418: 7415: 7413: 7410: 7408: 7405: 7403: 7400: 7398: 7395: 7393: 7390: 7388: 7385: 7383: 7380: 7378: 7375: 7371: 7368: 7366: 7363: 7362: 7361: 7358: 7356: 7353: 7351: 7348: 7346: 7343: 7341: 7338: 7336: 7333: 7331: 7328: 7326: 7323: 7321: 7318: 7316: 7313: 7309: 7306: 7305: 7304: 7301: 7299: 7296: 7294: 7291: 7290: 7288: 7286: 7280: 7274: 7271: 7269: 7266: 7264: 7261: 7259: 7256: 7254: 7251: 7249: 7246: 7244: 7241: 7237: 7234: 7233: 7232: 7229: 7227: 7224: 7222: 7219: 7215: 7212: 7211: 7210: 7207: 7205: 7202: 7200: 7197: 7193: 7190: 7188: 7185: 7183: 7180: 7179: 7178: 7175: 7171: 7168: 7166: 7163: 7162: 7161: 7158: 7154: 7151: 7149: 7146: 7144: 7141: 7140: 7139: 7136: 7134: 7131: 7130: 7128: 7125: 7120: 7116: 7110: 7107: 7105: 7102: 7100: 7097: 7095: 7092: 7090: 7089:Subsatellites 7087: 7085: 7082: 7080: 7077: 7075: 7072: 7070: 7067: 7065: 7062: 7060: 7057: 7056: 7054: 7052: 7049:Hypothetical 7046: 7043: 7034: 7031: 7027: 7024: 7022: 7019: 7017: 7014: 7012: 7009: 7005: 7002: 7000: 6997: 6996: 6995: 6992: 6991: 6990: 6987: 6983: 6980: 6978: 6975: 6974: 6973: 6970: 6966: 6963: 6961: 6958: 6956: 6953: 6951: 6948: 6946: 6943: 6941: 6938: 6936: 6933: 6931: 6928: 6926: 6923: 6922: 6921: 6918: 6916: 6915:Asteroid belt 6913: 6911: 6908: 6904: 6901: 6899: 6896: 6894: 6891: 6887: 6884: 6882: 6879: 6878: 6877: 6874: 6872: 6869: 6867: 6864: 6862: 6859: 6858: 6857: 6854: 6850: 6847: 6845: 6842: 6840: 6837: 6835: 6832: 6830: 6827: 6825: 6822: 6820: 6817: 6815: 6812: 6811: 6809: 6807: 6804: 6800: 6797: 6795: 6792: 6791: 6790: 6789:Minor planets 6787: 6785: 6782: 6780: 6777: 6775: 6772: 6771: 6769: 6767: 6757: 6751: 6748: 6746: 6743: 6741: 6738: 6736: 6733: 6731: 6728: 6726: 6723: 6720: 6716: 6713: 6711: 6708: 6707: 6705: 6703: 6699: 6691: 6688: 6687: 6686: 6683: 6679: 6676: 6675: 6674: 6671: 6667: 6664: 6663: 6662: 6659: 6655: 6652: 6651: 6650: 6647: 6643: 6640: 6638: 6635: 6634: 6633: 6630: 6626: 6623: 6621: 6618: 6616: 6613: 6611: 6608: 6606: 6603: 6602: 6601: 6598: 6594: 6591: 6590: 6589: 6586: 6582: 6579: 6577: 6574: 6572: 6569: 6567: 6564: 6563: 6562: 6559: 6555: 6552: 6550: 6547: 6545: 6542: 6540: 6537: 6535: 6532: 6530: 6527: 6526: 6525: 6522: 6518: 6515: 6513: 6510: 6508: 6505: 6503: 6500: 6498: 6495: 6493: 6490: 6488: 6485: 6483: 6480: 6478: 6475: 6473: 6470: 6469: 6468: 6465: 6461: 6458: 6456: 6453: 6451: 6448: 6446: 6443: 6441: 6438: 6437: 6436: 6433: 6429: 6426: 6424: 6421: 6420: 6419: 6416: 6412: 6409: 6407: 6404: 6403: 6401: 6400: 6398: 6396: 6392: 6384: 6381: 6379: 6376: 6374: 6371: 6369: 6366: 6364: 6361: 6359: 6356: 6354: 6351: 6349: 6346: 6344: 6341: 6340: 6339: 6336: 6330: 6327: 6325: 6322: 6321: 6320: 6317: 6313: 6310: 6308: 6305: 6304: 6303: 6300: 6299: 6298: 6295: 6291: 6288: 6286: 6283: 6281: 6278: 6276: 6273: 6272: 6271: 6268: 6267: 6265: 6263: 6258: 6254: 6251: 6250: 6245: 6239: 6238: 6234: 6232: 6231: 6227: 6225: 6224: 6220: 6218: 6217: 6213: 6211: 6210: 6206: 6204: 6203: 6199: 6197: 6196: 6192: 6190: 6189: 6185: 6183: 6180: 6178: 6175: 6173: 6170: 6168: 6165: 6163: 6162: 6158: 6156: 6153: 6151: 6148: 6146: 6143: 6141: 6138: 6136: 6133: 6132: 6087: 6083: 6076: 6071: 6069: 6064: 6062: 6057: 6056: 6053: 6041: 6038: 6036: 6033: 6031: 6028: 6027: 6025: 6021: 6011: 6008: 6006: 6003: 6001: 5998: 5996: 5993: 5991: 5988: 5986: 5985:Double planet 5983: 5982: 5980: 5976: 5968: 5965: 5963: 5960: 5958: 5955: 5954: 5953: 5950: 5948: 5945: 5944: 5942: 5938: 5932: 5929: 5927: 5924: 5922: 5919: 5918: 5916: 5912: 5906: 5903: 5901: 5898: 5897: 5895: 5891: 5888: 5884: 5878: 5877: 5873: 5872: 5870: 5868: 5864: 5858: 5855: 5853: 5850: 5848: 5845: 5843: 5840: 5838: 5837: 5833: 5832: 5830: 5828: 5824: 5819: 5813: 5807: 5793: 5790: 5789: 5787: 5783: 5777: 5774: 5773: 5771: 5767: 5761: 5760:Adlivun Cavus 5758: 5757: 5755: 5749: 5743: 5740: 5739: 5737: 5733: 5727: 5724: 5722: 5719: 5717: 5714: 5712: 5709: 5707: 5704: 5702: 5699: 5697: 5694: 5693: 5691: 5685: 5679: 5676: 5674: 5671: 5669: 5666: 5664: 5661: 5659: 5656: 5654: 5651: 5649: 5646: 5644: 5641: 5639: 5636: 5634: 5631: 5627: 5624: 5622: 5619: 5617: 5614: 5612: 5609: 5607: 5604: 5602: 5599: 5598: 5596: 5592: 5591: 5589: 5585: 5582: 5579: 5574: 5570: 5564: 5561: 5559: 5556: 5554: 5551: 5550: 5547: 5543: 5536: 5531: 5529: 5524: 5522: 5517: 5516: 5513: 5504: 5499: 5494: 5489: 5485: 5481: 5477: 5472: 5470: 5466: 5462: 5448: 5443: 5439: 5435: 5431: 5427: 5423: 5419: 5415: 5411: 5407: 5403: 5398: 5394: 5390: 5386: 5382: 5377: 5372: 5368: 5364: 5360: 5356: 5352: 5347: 5343: 5339: 5335: 5331: 5327: 5323: 5318: 5316: 5313: 5309: 5305: 5301: 5300: 5295: 5294: 5284: 5280: 5276: 5272: 5267: 5263: 5257: 5253: 5248: 5244: 5238: 5234: 5229: 5225: 5219: 5215: 5214: 5208: 5207: 5194: 5190: 5185: 5180: 5176: 5172: 5167: 5162: 5158: 5154: 5150: 5143: 5134: 5129: 5125: 5121: 5116: 5111: 5108:(1): L6–L10. 5107: 5103: 5099: 5092: 5084: 5080: 5076: 5072: 5068: 5064: 5059: 5054: 5050: 5046: 5045: 5037: 5029: 5025: 5020: 5015: 5011: 5007: 5002: 4997: 4993: 4989: 4985: 4978: 4970: 4966: 4962: 4958: 4953: 4948: 4944: 4940: 4935: 4930: 4926: 4922: 4918: 4911: 4895: 4894: 4889: 4883: 4874: 4869: 4862: 4860: 4845: 4844: 4839: 4832: 4830: 4823: 4819: 4818:New Scientist 4814: 4799: 4795: 4788: 4780: 4776: 4772: 4768: 4764: 4760: 4755: 4750: 4746: 4742: 4741: 4733: 4718: 4717: 4712: 4705: 4690: 4683: 4668: 4662: 4647: 4641: 4626: 4625: 4620: 4613: 4605: 4601: 4596: 4591: 4586: 4581: 4577: 4573: 4569: 4562: 4554: 4550: 4545: 4540: 4536: 4532: 4527: 4522: 4518: 4514: 4510: 4497: 4489: 4485: 4479: 4471: 4470: 4465: 4459: 4444: 4443: 4438: 4431: 4423: 4419: 4414: 4409: 4405: 4401: 4396: 4391: 4387: 4383: 4382: 4377: 4370: 4368: 4358: 4353: 4349: 4345: 4341: 4337: 4333: 4329: 4325: 4318: 4310: 4309: 4304: 4298: 4289: 4277: 4273: 4272: 4264: 4250:on 2008-01-03 4249: 4245: 4238: 4236: 4221: 4217: 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128: 122: 120: 116: 115:dwarf planets 112: 108: 103: 102: 96: 92: 88: 86: 82: 78: 74: 70: 66: 62: 58: 50: 46: 40: 33: 29: 22: 7874:Solar System 7861: 7778:Each arrow ( 7700:Local Bubble 7686:Solar System 7684: 7477:Planetesimal 7432:Kuiper cliff 7160:Space probes 7133:Colonization 6972:Kirkwood gap 6893:Saturn Moons 6806:Planetesimal 6270:Terrestrials 6235: 6228: 6221: 6214: 6207: 6200: 6193: 6186: 6159: 6082:Solar System 5990:Dwarf planet 5967:Roger Putnam 5876:New Horizons 5874: 5834: 5716:Piccard Mons 5696:Baret Montes 5483: 5479: 5454:. 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Cowell 451: 438: 427: 409: 405: 391: 349:of Jupiter, 324: 317: 310: 294: 258: 235: 227: 200: 176: 143: 123: 119:Solar System 99: 89: 54: 7844:Outer space 7832:Spaceflight 7741:Local Sheet 7735:Local Group 7518:Rubble pile 7506:Roche limit 7501:Ring system 7452:Outer space 7427:Kuiper belt 7397:Hill sphere 7392:Hills cloud 7340:Debris disk 7335:Cosmic dust 7119:Exploration 7074:Planet Nine 7059:Fifth giant 7033:Hills cloud 6994:Kuiper belt 6965:exceptional 6881:Trojan camp 6010:Kuiper belt 5867:Exploration 5753:depressions 5751:Valleys and 5726:Wright Mons 5486:: L72–L77. 5328:(5): 2000. 4357:11336/37037 3935:Physorg.com 3372:(5): 2000. 2993:(8): 1005. 1230:Probability 1204:Planet Nine 1181:super-Earth 1137:Planet Nine 1087:200 AU 1047:Planet Nine 952:Kuiper belt 646:E. C. Bower 383:Planet Nine 290:Planet Nine 150:Planet Nine 71:to explain 7868:Categories 7760:Local Hole 7707:Gould Belt 7447:Oort cloud 7283:Formation, 7273:Deep space 7109:Vulcanoids 7026:Oort cloud 6950:first 1000 6886:Greek camp 6784:Meteoroids 6779:Damocloids 6725:Charikloan 5921:Alan Stern 5776:Luna Linea 5616:Vucub-Came 5611:Harrington 5553:Atmosphere 5493:2306.11109 5456:2009-04-10 5166:2102.05601 5115:2202.01693 5058:1602.06116 4873:1512.02650 4849:2016-01-22 4695:2011-02-19 4691:. NASA/JPL 4673:2013-04-01 4652:2013-04-01 4585:2309.03885 4395:1704.02444 4254:2008-07-13 4225:2016-01-20 4199:22 January 4148:2102.02220 4089:1706.06981 4028:1604.05881 3916:2012-05-21 3773:2010-08-06 3586:2024-09-11 3558:2008-06-25 3532:2007-02-22 3507:2011-07-05 3478:2008-06-20 3453:2011-07-05 3225:2024-09-11 2583:2014-11-05 2544:2008-06-29 2523:2007-03-25 2489:2024-09-11 2209:2008-09-04 2102:2019-12-07 2051:1612.07774 1936:20 January 1885:1601.05438 1847:2016-01-25 1553:References 1541:Pan-STARRS 1414:Oort cloud 1382:Oort cloud 1315:heliopause 1045:See also: 1000:Alan Stern 967:Mike Brown 936:See also: 913:Pioneer 11 907:Pioneer 10 897:Voyager 2' 736:0.91 Earth 561:precovered 535:time lapse 246:CHF Peters 160:See also: 7721:Milky Way 7714:Orion Arm 7482:Formation 7467:Migration 7462:Disrupted 7330:Coatlicue 7298:Accretion 7285:evolution 7231:Asteroids 7143:astronomy 7138:Discovery 6999:Cubewanos 6920:Asteroids 6750:Quaoarian 6740:Neptunian 6730:Chironean 6715:Saturnian 6497:Enceladus 6035:Mythology 5940:Discovery 5886:Astronomy 5689:mountains 5687:Hills and 5573:Geography 5430:0028-0836 5385:0028-0836 5193:231861808 5159:(2): 59. 5083:119116589 5001:1407.5894 4969:118554088 4961:1745-3933 4934:1404.0258 4754:1004.4584 4604:1745-3925 4526:1407.5894 4469:Space.com 4388:(2): 62. 4308:Space.com 4282:2 January 4173:231802033 4055:119110892 3994:118622180 3967:1406.0715 3854:Space.com 3834:118414447 3809:0712.2198 3734:0004-637X 3339:0035-8711 3290:0004-637X 3234:cite news 3220:0190-8286 3182:122053270 3068:119386667 3060:0004-6256 2922:121483531 2914:0004-6280 2878:0035-8711 2826:0004-6280 2788:Baade, W. 2657:0035-8711 2413:0021-1753 2157:117727302 2149:0021-8286 2078:119325788 2044:(3): 91. 2019:144255699 2003:0021-1753 1878:(2): 22. 1771:122930471 1707:0028-0836 1601:0075-9317 1453:telescope 1374:gas giant 1267:eccentric 925:Voyager 2 919:Voyager 1 829:eccentric 638:residuals 631:director 574:asteroids 318:In 1909, 299:director 259:In 1879, 228:In 1848, 107:asteroids 101:Voyager 2 85:perturbed 7774:Universe 7612:Moonlets 7192:programs 7165:timeline 7153:timeline 7084:Planet X 7079:Planet V 7016:Sednoids 7004:Plutinos 6977:Centaurs 6955:families 6690:Dysnomia 6678:Xiangliu 6673:Gonggong 6661:Makemake 6620:Kerberos 6507:Hyperion 6445:Callisto 6440:Ganymede 6373:Gonggong 6368:Makemake 6223:Gonggong 6216:Makemake 5947:Planet X 5847:Kerberos 5643:Hayabusa 5621:Hun-Came 5601:Safronov 5578:features 5469:Planet X 5393:29058579 5028:26844167 4900:11 March 4779:44204219 4553:26844167 4442:Newsweek 4276:Archived 4116:55469849 3646:17110153 3575:(2021). 3472:BBC News 3110:: 1476. 2957:17744185 2790:(1934). 2437:26512655 2261:(1998). 1826:24670765 1749:(1): 4. 1715:11373654 1512:See also 1166:Sheppard 1162:Trujillo 1022:Gonggong 1010:Makemake 833:inclined 761:Rawlins 455:Arequipa 430:ecliptic 373:Planet X 359:Ganymede 269:1889 III 265:1862 III 254:New York 236:In 1850 137:, and a 7856:Science 7808:Physics 7794:Portals 7595:Related 7574:by size 7263:Neptune 7248:Jupiter 7199:Mercury 7124:outline 7069:Phaeton 7064:Nemesis 7051:objects 6903:Neptune 6876:Jupiter 6856:Trojans 6849:Neptune 6834:Jupiter 6814:Mercury 6745:Haumean 6735:Uranian 6717: ( 6637:Hiʻiaka 6571:Proteus 6561:Neptune 6549:Miranda 6539:Umbriel 6529:Titania 6517:all 146 6482:Iapetus 6435:Jupiter 6329:Neptune 6307:Jupiter 6275:Mercury 6257:Planets 6182:Neptune 6167:Jupiter 6140:Mercury 6030:Fiction 6023:Related 6000:Plutino 5978:General 5785:Craters 5678:Voyager 5658:Pioneer 5653:Morgoth 5587:Regions 5563:Geology 5558:Climate 5438:7658694 5410:Bibcode 5363:Bibcode 5330:Bibcode 5308:YouTube 5279:Bibcode 5171:Bibcode 5120:Bibcode 5063:Bibcode 5006:Bibcode 4939:Bibcode 4803:10 July 4759:Bibcode 4722:7 March 4531:Bibcode 4448:23 June 4422:5756310 4400:Bibcode 4336:Bibcode 4288:YouTube 4153:Bibcode 4094:Bibcode 4033:Bibcode 3972:Bibcode 3886:18 July 3860:18 July 3814:Bibcode 3742:7738201 3714:Bibcode 3676:25 June 3624:Bibcode 3374:Bibcode 3317:Bibcode 3270:Bibcode 3160:Bibcode 3112:Bibcode 3040:Bibcode 2995:Bibcode 2937:Science 2894:Bibcode 2856:Bibcode 2804:Bibcode 2760:Bibcode 2686:Bibcode 2635:Bibcode 2441:p. 563. 2278:Bibcode 2233:Bibcode 2192:Bibcode 2129:Bibcode 2056:Bibcode 1912:2701020 1890:Bibcode 1834:4393431 1806:Bibcode 1751:Bibcode 1723:5135498 1581:Bibcode 1482:Cassini 1353:2020 MK 1342:2020 BE 1331:2018 AG 1320:2018 VG 1308:Cassini 1287:2012 VP 1263:plutino 1174:2012 VP 1152:2012 VP 971:2003 UB 839:of the 750:Kuiper 725:1 Earth 696:⁄ 686:methane 656:at the 611:Mercury 602:perturb 343:Jupiter 313:Münster 273:aphelia 139:Jupiter 75:in the 57:Neptune 7769: 7762: 7755: 7730: 7723: 7716: 7709: 7702: 7695: 7688: 7617:Syzygy 7539:Comets 7472:System 7457:Planet 7350:EXCEDE 7258:Uranus 7253:Saturn 7243:Comets 7236:mining 7214:mining 7104:Vulcan 6945:active 6940:Hygiea 6935:Pallas 6898:Uranus 6844:Uranus 6839:Saturn 6774:Comets 6766:bodies 6764:System 6710:Jovian 6654:Weywot 6649:Quaoar 6642:Namaka 6632:Haumea 6605:Charon 6581:all 16 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