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Encyclopedia > Pluto
Pluto   Astronomical symbol of Pluto

Map of Pluto based on Charon eclipses, approximately true colour and giving the highest resolution currently possible
Discovery
Discovered by: Clyde W. Tombaugh
Discovery date: February 18, 1930
Orbital characteristics
Epoch J2000
Aphelion 7,375,927,931 km
49.30503287 AU
Perihelion: 4,436,824,613 km
29.65834067 AU
Semi-major axis: 5,906,376,272 km
39.48168677 AU
Eccentricity: 0.24880766
Orbital period: 90,613.3055 day
248.09 yr
Synodic period: 366.73 day
Avg. orbital speed: 4.666 km/s
Inclination: 17.14175°
11.88° to Sun's equator
Longitude of ascending node: 110.30347°
Argument of perihelion: 113.76329°
Satellites: 3
Physical characteristics
Mean radius: 1,195 km [1]
0.19 Earths
Surface area: 1.795×107 km²
0.033 Earths
Volume: 7.15×109 km³
0.0066 Earths
Mass: 1.305 ± 0.007×1022 kg [1]
0.0021 Earths
Mean density: 2.03 ± 0.06 g/cm³ [1]
Equatorial surface gravity: 0.58 m/s²
0.059 g
Escape velocity: 1.2 km/s
Sidereal rotation period: −6.387230 day
6 d 9 h 17 m 36 s
Rotation velocity at equator: 47.18 km/h
Axial tilt: 119.591 ± 0.014° (to orbit)[1][2]
Right ascension of North pole: 133.046 ± 0.014°[1]
Declination of North pole: -6.145 ± 0.014°[1]
Albedo: 0.49–0.66 (varies by 35%) [2] [3]
Surface temp.:
   Kelvin
min mean max
33 K 44 K 55 K
Apparent magnitude: up to 13.65 (mean is 15.1) [3]
Angular diameter: 0.065" to 0.115" [3][4]
Adjectives: Plutonian
Atmosphere
Surface pressure: 0.30 Pa (summer maximum)
Composition: nitrogen, methane

Pluto (pronounced /ˈpluːtoʊ/, from Latin: Plūto, Greek: Πλούτων), also designated 134340 Pluto, is the second-largest known dwarf planet in the Solar System (after Eris) and the tenth-largest body observed directly orbiting the Sun. Originally classified as a planet, Pluto is now recognised as the largest member of a distinct region called the Kuiper belt. Like other members of the belt, it is composed primarily of rock and ice and is relatively small; approximately a fifth the mass of the Earth's Moon and a third its volume. It has an eccentric orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun, and is highly inclined with respect to the planets. As a result, Pluto occasionally comes closer to the Sun than the planet Neptune does. Pluto is the second-largest dwarf planet in the Solar system. ... Image File history File links Pluto_symbol. ... Image File history File links Pluto. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... An image of Clyde Tombaugh Clyde William Tombaugh (February 4, 1906 – January 17, 1997) was an American astronomer who discovered the dwarf planet Pluto in 1930. ... is the 49th day of the year in the Gregorian calendar. ... Year 1930 (MCMXXX) was a common year starting on Wednesday (link will display 1930 calendar) of the Gregorian calendar. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... The J2000. ... A diagram of Keplerian orbital elements. ... The astronomical unit (AU or au or a. ... A diagram of Keplerian orbital elements. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... For the science fiction novella by William Shunn, see Inclination (novella). ... The Longitude of the ascending node (☊, also noted Ω) is one of the orbital elements used to specify the orbit of an object in space. ... The argument of periapsis (ω) is the orbital element describing the angle between an orbiting bodys ascending node (the point where the body crosses the plane of reference from South to North) and its periapsis (the point of closest approach to the central body), measured in the orbital plane and... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... The planet Pluto has three known moons. ... In mathematics, a spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes. ... For other uses, see Volume (disambiguation). ... For other uses, see Mass (disambiguation). ... For other uses, see Density (disambiguation). ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... The term g force or gee force refers to the symbol g, the force of acceleration due to gravity at the earths surface. ... Space Shuttle Atlantis launches on mission STS-71. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... For other uses, see Albedo (disambiguation). ... For other uses, see Temperature (disambiguation). ... For other uses, see Kelvin (disambiguation). ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... The angular diameter of an object as seen from a given position is the diameter measured as an angle. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... For other uses, see Pascal. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Latin (disambiguation). ... Minor planet names, including those of asteroids and dwarf planets, are managed by the Minor Planet Center, a branch of the IAU. They consist, in their final form, of a number originally assigned in approximate order of discovery, now assigned only after the orbit is determined, coupled with a name... Artists impression of Pluto (background) and Charon (foreground). ... This article is about the Solar System. ... Absolute magnitude: −1. ... Sol redirects here. ... This article is about the astronomical term. ... The Kuiper belt, derived from data from the Minor Planet Center. ... This article is about Earth as a planet. ... This article is about Earths moon. ... (This page refers to eccitricity in astrodynamics. ... The astronomical unit (AU or au or a. ... For other uses, see Neptune (disambiguation). ...


Pluto and its largest moon, Charon, are often treated together as a binary system because the barycentre of their orbits does not lie within either body.[5] The International Astronomical Union (IAU) has yet to formalise a definition for binary dwarf planets, and until it passes such a ruling, Charon is classified as a moon of Pluto.[6] Pluto has two known smaller moons, Nix and Hydra, discovered in 2005.[7] Charon (shair-ən or kair-ən (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... A binary system is an astronomy term referring to two objects in space, usually stars, which are so close that their gravitational forces attract one another into a mutual orbit. ... In physics, the center of mass of a system of particles is a specific point at which, for many purposes, the systems mass behaves as if it were concentrated. ... IAU redirects here. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ...


From the time of its discovery in 1930 until 2006, Pluto was counted as the Solar System's ninth planet. In the late 20th and early 21st centuries, however, many objects similar to Pluto were discovered in the outer solar system, notably the scattered disc object Eris, which is 27% more massive than Pluto.[8] On August 24, 2006 the IAU defined the term "planet" for the first time. This definition excluded Pluto, and reclassified it as a member of the new category of dwarf planets along with Eris and Ceres.[9] After the reclassification, Pluto was added to the list of minor planets and given the number 134340.[10][11] A scattered disk object (or scattered disc object or SDO) is a trans-Neptunian object of the Kuiper belt with a very eccentric orbit. ... is the 236th day of the year (237th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The final definition left the solar system with eight planets. ... Spectral type: G[8] Absolute magnitude: 3. ... Minor planets, or asteroids or planetoids, are minor celestial bodies of the Solar system orbiting the Sun (mostly Small solar system bodies) that are smaller than major planets, but larger than meteoroids (commonly defined as being 10 meters across or less[1]), and that are not comets. ... In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ...

Contents

Discovery

The discovery of Pluto was rooted in a misconception. Before it was found, scientists believed that its existence had been indirectly determined through discrepancies observed in the orbit of Uranus, which was thought to be the result of gravitational interactions with an as-yet-unknown planet. However, Pluto is not massive enough to affect the orbits of the planets, and a re-evaluated increase in the mass of Neptune showed that the supposed gravitational discrepancies do not exist.


Planet X

Main article: Planet X

In the 1840s, using Newtonian mechanics, Urbain Le Verrier predicted the position of the then-undiscovered planet Neptune after analysing perturbations in the orbit of Uranus. Hypothesising that the perturbations were caused by the gravitational pull of another planet, Le Verrier sent his calculations to German astronomer Johann Gottfried Galle. On September 23, 1846, the night following his receipt of the letter, Galle and his student Heinrich d'Arrest found Neptune precisely where Le Verrier had predicted.[12] For other uses, see Planet X (disambiguation). ... It has been suggested that this article or section be merged with Classical mechanics. ... Urbain Le Verrier. ... For other uses, see Neptune (disambiguation). ... For other uses, see Uranus (disambiguation). ... Johann Gottfried Galle Johann Gottfried Galle (June 9, 1812 in Radis, Saxony-Anhalt – July 10, 1910 in Potsdam, Brandenburg) was a German astronomer at the Berlin Observatory who, with the assistance of student Heinrich Louis dArrest, was the first person to view the planet Neptune, and know what he... is the 266th day of the year (267th in leap years) in the Gregorian calendar. ... 1846 was a common year starting on Thursday (see link for calendar). ... Heinrich Louis dArrest (July 13, 1822 – June 14, 1875) was a Prussian astronomer, born in Berlin. ... For other uses, see Neptune (disambiguation). ...


Observations of Neptune in the late 19th century caused astronomers to speculate that Uranus' orbit was being disturbed by another planet in addition to Neptune. In 1905, Percival Lowell, a wealthy Bostonian who had founded the Lowell Observatory in Flagstaff, Arizona in 1894, started an extensive project in search of a possible ninth planet, which he termed "Planet X".[13] Lowell's hope in tracking down Planet X was to establish his scientific credibility, which had been dented due to his extolling the hypothesis that channel-like features visible on the surface of Mars were in fact canals constructed by an intelligent civilisation.[14] By 1909, Lowell and William H. Pickering had suggested several possible celestial coordinates for such a planet.[15] Lowell and his observatory conducted his search from 1905 until his death in 1916, but to no avail. Lowell's disappointment at not locating Planet X, according to one friend, "virtually killed him".[16] Percival Lowell (March 13, 1855 – November 12, 1916) was an author, mathematician, and esteemed astronomer who fueled speculation that there were canals on Mars, founded the Lowell Observatory in Flagstaff, Arizona, and formed the beginning of the work and theories that led to the discovery of Pluto 14 years after... Lowell Observatory Percival observing Mars from the Clark telescope at the Lowell Observatory. ... Nickname: Location in Coconino County the state of Arizona Coordinates: , Country State County Coconino County Government  - Mayor Joseph C. Donaldson Area  - City  98. ... For other uses, see Planet X (disambiguation). ... Adjectives: Martian Atmosphere Surface pressure: 0. ... For a time in the late 19th and early 20th centuries, it was believed that there were canals on Mars. ... William Henry Pickering (February 15, 1858 – January 17, 1938) was an American astronomer, brother of Edward Charles Pickering. ...


Constance Lowell, Percival Lowell's widow, subsequently embroiled the observatory in a decade-long legal battle to wrest the observatory's million-dollar portion of Lowell's legacy for herself, which meant that its search for Planet X could not resume until 1929.[17] In that year, the observatory's director, Vesto Melvin Slipher, summarily handed the job of locating Planet X to Clyde Tombaugh, 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.[17] Vesto Melvin Slipher (November 11, 1875 – November 8, 1969) was an American astronomer. ... An image of Clyde Tombaugh Clyde William Tombaugh (February 4, 1906 – January 17, 1997) was an American astronomer who discovered the dwarf planet Pluto in 1930. ... This article is about the U.S. state. ...

Discovery photographs of Pluto
Discovery photographs of Pluto

Tombaugh's task was to systematically image the night sky in pairs of photographs taken two weeks apart, then examine each pair and determine if any objects had shifted position in that time. Using a machine called a blink comparator, he rapidly shifted back and forth between views of each of the plates, to create the illusion of movement of any objects that had changed position or appearance between photographs. On February 18, 1930, after nearly a year of searching, Tombaugh discovered a possible moving object on photographic plates taken on January 23 and January 29 of that year. A lesser-quality photograph taken on January 20 helped confirm the movement. Tombaugh walked into Slipher's office and declared, "Doctor Slipher, I have found your Planet X."[18] After the observatory obtained further confirmatory photographs, news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930. The new object would later be found on photographs dating back to March 19, 1915.[15] Image File history File links Download high-resolution version (1779x1101, 674 KB) This image is a faithful digitalization of a unique historic photograph, and the copyright for it is most likely held by the photographer who took the photograph or the agency employing the photographer. ... Image File history File links Download high-resolution version (1779x1101, 674 KB) This image is a faithful digitalization of a unique historic photograph, and the copyright for it is most likely held by the photographer who took the photograph or the agency employing the photographer. ... This blink comparator at Lowell Observatory was used in the discovery of Pluto. ... is the 49th day of the year in the Gregorian calendar. ... Year 1930 (MCMXXX) was a common year starting on Wednesday (link will display 1930 calendar) of the Gregorian calendar. ... is the 23rd day of the year in the Gregorian calendar. ... is the 29th day of the year in the Gregorian calendar. ... is the 20th day of the year in the Gregorian calendar. ... Harvard College Observatory, about 1900. ... is the 72nd day of the year (73rd in leap years) in the Gregorian calendar. ... Year 1930 (MCMXXX) was a common year starting on Wednesday (link will display 1930 calendar) of the Gregorian calendar. ... is the 78th day of the year (79th in leap years) in the Gregorian calendar. ... Year 1915 (MCMXV) was a common year starting on Friday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Thursday[1] of the 13-day-slower Julian calendar). ...


Naming

Venetia Burney, the girl who named Pluto
Venetia Burney, the girl who named Pluto
See also: Pluto (mythology)

The right to name the new object belonged to the Lowell Observatory. Tombaugh urged Slipher to suggest a name for the new object quickly before someone else did.[13] Name suggestions poured in from all over the world. Constance Lowell proposed Zeus, then Lowell, and finally her own first name. These suggestions were disregarded.[19] Image File history File links Venetia_phair. ... Image File history File links Venetia_phair. ... Venetia Phair at age 11 Venetia Katherine Douglas Phair (née Burney) (born 1919) was the first person to suggest the name Pluto for the planet[1] discovered by Clyde W. Tombaugh in 1930. ... For other uses, see Pluto (disambiguation). ... For other uses, see Zeus (disambiguation). ...


The name Pluto was first suggested by Venetia Burney (later Venetia Phair), an eleven-year-old schoolgirl in Oxford, England.[20] Venetia was interested in classical mythology as well as astronomy, and considered the name, one of the alternate names of Hades, the Greek god of the Underworld, appropriate for such a presumably dark and cold world. She suggested it in a conversation with her grandfather Falconer Madan, a former librarian of Oxford University's Bodleian Library. Madan passed the name to Professor Herbert Hall Turner, who then cabled it to colleagues in America.[21] Venetia Phair at age 11 Venetia Katherine Douglas Phair (née Burney) (born 1919) was the first person to suggest the name Pluto for the planet[1] discovered by Clyde W. Tombaugh in 1930. ... Oxford is a city and local government district in Oxfordshire, England, with a population of 134,248 ( 2001 census). ... For other uses, see England (disambiguation). ... Classical or Greco-Roman mythology usually refers to the mythology, and the associated polytheistic rituals and practices, of Classical Antiquity. ... Hades, Greek god of the underworld, enthroned, with his bird-headed staff, on a red-figure Apulian vase made in the 4th century BC. For other uses, see Hades (disambiguation). ... Falconer Madan (15 April 1851-22 May 1935) was Librarian of the Bodleian Library of Oxford University. ... The Librarian, a 1556 painting by Giuseppe Arcimboldo A librarian is an information professional trained in library science and information science: the organization and management of information and service to people with information needs. ... The University of Oxford, located in the city of Oxford in England, is the oldest university in the English-speaking world. ... Entrance to the Library, with the coats-of-arms of several Oxford colleges The Bodleian Library, the main research library of the University of Oxford, is one of the oldest libraries in Europe, and in England is second in size only to the British Library. ... Herbert Hall Turner (August 13, 1861 – August 20, 1930) was a British astronomer and seismologist. ...


The object was officially named on March 24, 1930.[22] Each member of the Lowell Observatory was allowed to vote on a short-list of three: "Minerva" (which was already the name for an asteroid), "Cronus" (which had garnered a bad reputation after being suggested by an unpopular astronomer named Thomas Jefferson Jackson See), and Pluto. Pluto received every vote.[23] The name was announced on May 1, 1930.[20] Upon the announcement, Madan gave Venetia five pounds as a reward.[20] is the 83rd day of the year (84th in leap years) in the Gregorian calendar. ... Year 1930 (MCMXXX) was a common year starting on Wednesday (link will display 1930 calendar) of the Gregorian calendar. ... Head of Minerva by Elihu Vedder, 1896 For other uses, see Minerva (disambiguation). ... Cronus is not to be confused with Chronos, the personification of time. ... Thomas Jefferson Jackson (T. J. J.) See, (1866 to July 4, 1962). ... is the 121st day of the year (122nd in leap years) in the Gregorian calendar. ... Year 1930 (MCMXXX) was a common year starting on Wednesday (link will display 1930 calendar) of the Gregorian calendar. ... GBP redirects here. ...


The name Pluto was intended to evoke the initials of the astronomer Percival Lowell, a desire echoed in the P-L monogram that is Pluto's astronomical symbol ( ♇).[24] Pluto's astrological symbol resembles that of Neptune ( ), but has a circle in place of the middle prong of the trident ( ). Percival Lowell (March 13, 1855 – November 12, 1916) was an author, mathematician, and esteemed astronomer who fueled speculation that there were canals on Mars, founded the Lowell Observatory in Flagstaff, Arizona, and formed the beginning of the work and theories that led to the discovery of Pluto 14 years after... The Chi-Rho, a monogram of the first two letters in the Greek word for Christ E and L embroider for clothes and bedding, for a wife by the initials E L or L E A monogram is a motif made by overlapping or combining two or more letters or... Chinese Celestial symbols on an antique bronze mirror Astronomical symbols are symbols used to represent various celestial objects, theoretical constructs and observational events. ... Image File history File links Pluto_symbol. ... ... For other uses, see Neptune (disambiguation). ... Image File history File links Neptune_symbol. ... Image File history File links Pluto's_astrological_symbol. ...


In the Chinese, Japanese, and Korean languages, the name was translated as underworld king star (冥王星),[25] suggested by Houei Nojiri in 1930.[26] In Vietnamese it is named after Yama (Sao Diêm Vương), the Guardian of Hell in Buddhist mythology. Yama (Devanāgarī यम) is also used in India, as it is the deity of Hell in Hindu mythologies. Houei Nojiri (15 November 1885 – 30 October 1977) was a Japanese essayist and astronomer. ... Tibetan Dharmapala at the Field Museum in Chicago, Illinois Yama is the name of the Buddhist god and judge of the dead, who presides over the Buddhist Narakas (Pāli: Nirayas), Hells or Purgatories. Although ultimately based on the god Yama of the Hindu Vedas, the Buddhist Yama has developed... A replica of an ancient statue found among the ruins of a temple at Sarnath Buddhism is a philosophy based on the teachings of the Buddha, Siddhārtha Gautama, a prince of the Shakyas, whose lifetime is traditionally given as 566 to 486 BCE. It had subsequently been accepted by... () is an abugida script used to write several Indo-Aryan languages, including Sanskrit, Hindi, Gujarati,Marathi, Sindhi, Bihari, Bhili, Marwari, Konkani, Bhojpuri, Pahari (Garhwali and Kumaoni), Santhali, Nepali, Newari, Tharu and sometimes Kashmiri and Romani. ...

Demise of Planet X

Once found, Pluto's faintness and lack of a visible disc cast doubt on the idea that it could be Lowell's Planet X. Throughout the mid-20th century, estimates of Pluto's mass were continually revised downward. In 1978, the discovery of Pluto's moon Charon allowed the precise measurement of Pluto's mass for the first time. Its mass, roughly 2 percent that of the Earth, was far too small to account for the discrepancies in Uranus. Subsequent searches for an alternate Planet X, notably by Robert Harrington,[27] failed. In 1993, Miles Standish used data from Voyager 2's 1989 flyby of Neptune, which had revised the planet's total mass downward by 0.5 percent, to recalculate its gravitational effect on Uranus. With the new figures added in, the discrepancies, and with them Planet X, vanished.[28] Today the overwhelming consensus among astronomers is that Planet X, as Lowell defined it, does not exist. Lowell had made a prediction of Planet X's position in 1915 which was fairly close to Pluto's actual position at that time; however, Ernest W. Brown concluded almost immediately that this was a coincidence, a view still held today, which makes Tombaugh's discovery even more surprising.[29] Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... There are a number of people named Robert Harrington, including two astronomers: Robert G. Harrington (? – ?) astronomer, discovered or co-discovered numerous comets and globular cluster Palomar 12. ... Signing of the Mayflower Compact Myles Standish (c. ... Trajectory Voyager 2 is an unmanned interplanetary spacecraft, launched on August 20, 1977. ... For other uses, see Neptune (disambiguation). ... Ernest William Brown (November 29, 1866 – July 22, 1938) was a British astronomer. ...


Physical characteristics

The largest plutinos compared in size, albedo and colour.
The largest plutinos compared in size, albedo and colour.
Possible structure of Pluto.
1. Frozen nitrogen
2. Water ice
3. Silicate and water ice

Pluto's distance from Earth makes in-depth investigation difficult. Many details about Pluto will remain unknown until 2015, when the New Horizons spacecraft is expected to arrive there.[30] Image File history File links ThePlutinos_Size_Albedo_Color2. ... Image File history File links ThePlutinos_Size_Albedo_Color2. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... For other uses, see Albedo (disambiguation). ... In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ...


Appearance and composition

Pluto's apparent magnitude is 15.1 on average, brightening to 13.65 at perihelion.[3] To see it, a telescope is required; around 30 cm aperture desirable.[31] It looks indistinct and star-like even in very large telescopes because its angular diameter is only 0.11". The colour of Pluto is light brown with a very slight tint of yellow.[32] The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... The angular diameter of an object as seen from a given position is the diameter measured as an angle. ...


Spectroscopic analysis of Pluto's surface reveals it to be composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide.[33][34] Distance and limits on telescope technology make it currently impossible to directly photograph surface details on Pluto. Images from the Hubble Space Telescope barely show any distinguishable surface definitions or markings.[35] Spectroscopy is the study of spectra, ie. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ...


The best images of Pluto derive from brightness maps created from close observations of eclipses by its largest moon, Charon. Using computer processing, observations are made in brightness factors as Pluto is eclipsed by Charon. For example, eclipsing a bright spot on Pluto makes a bigger total brightness change than eclipsing a gray spot. Using this technique, one can measure the total average brightness of the Pluto-Charon system and track changes in brightness over time.[36] Maps composed by the Hubble Space Telescope reveal that Pluto's surface is remarkably heterogeneous, a fact also evidenced by its lightcurve, and by periodic variations in its infrared spectra. The face of Pluto oriented toward Charon contains more methane ice, while the opposite face contains more nitrogen and carbon monoxide ice. This makes Pluto the second most contrasted body in the Solar System after Iapetus.[37] The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... Look up Heterogeneous in Wiktionary, the free dictionary. ... Methane is a chemical compound with the molecular formula . ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... R-phrases , , , , S-phrases , , , , Flash point Flammable gas Related Compounds Related oxides carbon dioxide; carbon suboxide; dicarbon monoxide; carbon trioxide Supplementary data page Structure and properties n, εr, etc. ... Iapetus (eye-ap-É™-tÉ™s, IPA , Greek Ιαπετός) is the third-largest moon of Saturn, discovered by Giovanni Domenico Cassini in 1671. ...


The Hubble Space Telescope places Pluto's density at between 1.8 and 2.1 g/cm³, suggesting its internal composition consists of roughly 50–70 percent rock and 30–50 percent ice.[34] Because decay of radioactive minerals would eventually heat the ices enough for them to separate from rock, scientists expect that Pluto's internal structure is differentiated, with the rocky material having settled into a dense core surrounded by a mantle of ice. It is also possible that such heating may continue into the present time, creating a subsurface ocean of liquid water.[38] The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... Earth cutaway from core to exosphere. ... Earth cutaway from core to exosphere. ...


Mass and size

Pluto's volume is about 0.21% that of Earth
Pluto's volume is about 0.21% that of Earth

Astronomers, assuming Pluto to be Lowell's Planet X, initially calculated its mass on the basis of its presumed effect on Neptune and Uranus. In 1955, Pluto was calculated to be roughly the mass of the Earth, with further calculations in 1971 bringing the mass down to roughly that of Mars.[39] However, in 1976, David Cuikshank, Carl Pilcher and David Morrison of the University of Hawaii calculated Pluto's albedo for the first time, and found it matched that for methane ice, which meant Pluto had to be exceptionally bright, and therefore could not be more than 1 percent the mass of the Earth.[39][40] Image File history File linksMetadata Download high resolution version (1500x1501, 716 KB)Rough comparison of the sizes of Earth and Pluto. ... Image File history File linksMetadata Download high resolution version (1500x1501, 716 KB)Rough comparison of the sizes of Earth and Pluto. ... This article is about the University of Hawaii system. ... For other uses, see Albedo (disambiguation). ... Methane is a chemical compound with the molecular formula . ...


The discovery of its satellite Charon in 1978 enabled a determination of the mass of the Pluto–Charon system by application of Newton's formulation of Kepler's third law. Once Charon's gravitational effect on Pluto was measured, estimates of Pluto's mass fell to 1.31×1022 kg; less than 0.24 percent that of the Earth.[41] Observations of Pluto in occultation with Charon were able to fix Pluto's diameter at roughly 2,390 km.[42] With the invention of adaptive optics astronomers were able to accurately determine its shape.[43] Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ... A deformable mirror can be used to correct wavefront errors in an astronomical telescope. ...


Ganymede Titan Callisto Io Moon Europa Triton Pluto

Pluto (bottom right) compared in size to the largest satellites in the solar system (from left to right and top to bottom): Ganymede, Titan, Callisto, Io, the Moon, Europa, and Triton
Pluto (bottom right) compared in size to the largest satellites in the solar system (from left to right and top to bottom): Ganymede, Titan, Callisto, Io, the Moon, Europa, and Triton

Among the objects of the Solar System, Pluto is not only smaller and much less massive than any planet, but at less than 0.2 lunar masses it is also smaller than seven of the moons: Ganymede, Titan, Callisto, Io, Earth's Moon, Europa and Triton. Pluto is more than twice the diameter and a dozen times the mass of Ceres, a dwarf planet in the asteroid belt. However, it is smaller than the dwarf planet Eris, a trans-Neptunian object discovered in 2005. Image File history File links Pluto_compared2. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... This article is about the natural satellite of Jupiter. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... There is also an asteroid named 204 Kallisto. ... Atmosphere Surface pressure: trace Composition: 90% sulfur dioxide Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter and, with a diameter of 3,642 kilometers, is the fourth largest moon in the Solar System. ... This article is about Earths moon. ... Apparent magnitude: 5. ... Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ... 1 Ceres (IPA , Latin: ) is a dwarf planet in the asteroid belt. ... Artists impression of Pluto (background) and Charon (foreground). ... For other uses, see Asteroid (disambiguation). ... Absolute magnitude: −1. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ...


Atmosphere

Artist's conception of the New Horizons spacecraft passing over Pluto, showing its tenuous atmosphere
Artist's conception of the New Horizons spacecraft passing over Pluto, showing its tenuous atmosphere

Pluto's atmosphere consists of a thin envelope of nitrogen, methane, and carbon monoxide, derived from the ices on its surface.[44] As Pluto moves away from the Sun, its atmosphere gradually freezes and falls to the ground. As it edges closer to the Sun, the temperature of Pluto's solid surface increases, causing the ices to sublimate into gas. This creates an anti-greenhouse effect; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. Scientists have recently discovered,[45] by use of the Submillimeter Array, that Pluto's temperature is 10 kelvins colder than expected. Image File history File links Size of this preview: 750 × 600 pixel Image in higher resolution (1500 × 1200 pixel, file size: 407 KB, MIME type: image/jpeg) Source File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Pluto New... Image File history File links Size of this preview: 750 × 600 pixel Image in higher resolution (1500 × 1200 pixel, file size: 407 KB, MIME type: image/jpeg) Source File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Pluto New... New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Methane is a chemical compound with the molecular formula . ... R-phrases , , , , S-phrases , , , , Flash point Flammable gas Related Compounds Related oxides carbon dioxide; carbon suboxide; dicarbon monoxide; carbon trioxide Supplementary data page Structure and properties n, εr, etc. ... For other uses, see Atmosphere (disambiguation). ... Sublimation of an element or substance is a conversion between the solid and the gas phases with no intermediate liquid stage. ... The Anti-Greenhouse Effect describes the cooling effect an atmosphere has on the ambient temperature of the planet. ... SWEAT is an OLN/TSN show hosted by Julie Zwillich that aired in 2003-2004. ... For other uses, see Skin (disambiguation). ... The submillimeter array under construction in 2002 The Submillimeter Array consists of 8 6 m diameter radio telescopes arranged as an interferometer for submillimeter wavelength observations. ... For other uses, see Kelvin (disambiguation). ...


Pluto was found to have an atmosphere from an occultation observation in 1985; the finding was confirmed and significantly strengthened by extensive observations of another occultation in 1988. When an object with no atmosphere occults a star, the star abruptly disappears; in the case of Pluto, the star dimmed out gradually.[46] From the rate of dimming, the atmospheric pressure was determined as 0.15 pascal, roughly 1/700,000 that of Earth.[47] In this July, 1997 still frame captured from video, the bright star Aldebaran has just reappeared on the dark limb of the waning crescent moon in this predawn occultation. ... For other uses, see Pascal. ...


In 2002, another occultation of a star by Pluto was observed and analysed by teams led by Bruno Sicardy of the Paris Observatory[48] and by James L. Elliot of MIT[49] and Jay Pasachoff of Williams College.[50] Surprisingly, the atmosphere was estimated to have had a pressure of 0.3 pascal, even though Pluto was farther from the Sun than in 1988, and hence should have been colder and had a less dense atmosphere. One explanation for this discrepancy is that in 1987 the south pole of Pluto came out of shadow for the first time in 120 years; as a result extra nitrogen sublimated from a polar cap. It will take decades for the excess nitrogen to condense out of the atmosphere.[51] Another stellar occultation was observed by the MIT-Williams College team of James Elliot and Jay Pasachoff and a Southwest Research Institute team led by Leslie Young on 12 June 2006 from sites in Australia.[52] This article does not cite any references or sources. ... James L. Elliot is a Professor of Physics; Professor of Earth, Atmospheric, and Planetary Sciences; and the Director, George R. Wallace, Jr. ... Mapúa Institute of Technology (MIT, MapúaTech or simply Mapúa) is a private, non-sectarian, Filipino tertiary institute located in Intramuros, Manila. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Williams College is a private, liberal arts college located in Williamstown, Massachusetts. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Southwest Research Institute (SwRI) is an independent, nonprofit applied research and development organization. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...


In October 2006, Dale Cruikshank of NASA/Ames Research Center (a New Horizons co-investigator) and his colleagues announced the spectroscopic discovery of ethane on Pluto's surface. This ethane is produced from the photolysis or radiolysis (i.e., the chemical conversion driven by sunlight and charged particles) of frozen methane on Pluto's surface and suspended in its atmosphere.[53] This article is about a chemical compound. ...


Orbit

Orbit of Pluto – ecliptic view. This 'side view' of Pluto's orbit (in red) shows its large inclination to Neptune's orbit (in blue). The ecliptic is horizontal
Orbit of Pluto – ecliptic view. This 'side view' of Pluto's orbit (in red) shows its large inclination to Neptune's orbit (in blue). The ecliptic is horizontal

Pluto's orbit is markedly different to those of the planets. The planets all orbit the Sun close to a flat reference plane called the ecliptic, and have nearly circular orbits. In contrast, Pluto's orbit is highly inclined relative to the ecliptic (over 17°) and highly eccentric (elliptical). This high eccentricity leads to a small region of Pluto's orbit lying closer to the Sun than Neptune's. Pluto was last interior to Neptune's orbit between February 7, 1979 and February 11, 1999. Detailed calculations indicate that the previous such occurrence lasted only fourteen years from July 11, 1735 to September 15, 1749, whereas between April 30, 1483 and July 23, 1503, it had again lasted for 20 years. Image File history File links TheKuiperBelt_Orbits_Pluto_Ecliptic. ... Image File history File links TheKuiperBelt_Orbits_Pluto_Ecliptic. ... Inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit and is the angular distance of the orbital plane from the plane of the reference (usually planets equator or the ecliptic), stated in degrees. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... This article is about the mathematical construct. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... Inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit and is the angular distance of the orbital plane from the plane of the reference (usually planets equator or the ecliptic), stated in degrees. ... (This page refers to eccitricity in astrodynamics. ... Elliptical may refer to: Ellipse: a shape and mathematical construct Elliptical trainer: an exercise machine This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... For other uses, see Neptune (disambiguation). ... is the 38th day of the year in the Gregorian calendar. ... Also: 1979 by Smashing Pumpkins. ... is the 42nd day of the year in the Gregorian calendar. ... This article is about the year. ... is the 192nd day of the year (193rd in leap years) in the Gregorian calendar. ... Events April 16 - The London premiere of Alcina by George Frideric Handel, his first the first Italian opera for the Royal Opera House at Covent Garden. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... Events While in debtors prison, John Cleland writes Fanny Hill (Memoirs of a Woman of Pleasure). ... is the 120th day of the year (121st in leap years) in the Gregorian calendar. ... Events The São Tomé settlement is founded. ... is the 204th day of the year (205th in leap years) in the Gregorian calendar. ... Year 1503 (MDIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. ...


Although this repeating pattern may suggest a regular structure, in the long term Pluto's orbit is in fact chaotic. While computer simulations can be used to predict its position for several million years (both forwards and backwards in time), after intervals longer than the Lyapunov time of 10–20 million years, it is impossible to determine exactly where Pluto will be because its position becomes too sensitive to unmeasurably small details of the present state of the solar system.[54][55] For example, at some specific time many millions of years from now, Pluto may be at aphelion or perihelion (or anywhere in between), with no way for us to predict which. This does not mean that the orbit of Pluto itself is unstable, however; only that its position along that orbit is impossible to determine far into the future. In fact, several resonances and other dynamical effects conspire to keep Pluto's orbit stable, safe from planetary collision or scattering. For other uses, see Chaos Theory (disambiguation). ... Time reversibility is an attribute of some stochastic processes. ... Categories: Wikipedia cleanup | Stub | Dynamical systems ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...


Neptune-avoiding orbit

Orbit of Pluto — polar view. This 'view from above' shows how Pluto's orbit (in red) is less circular than Neptune's (in blue), and how Pluto is sometimes closer to the Sun than Neptune. The darker halves of both orbits show where they pass below the plane of the ecliptic. The positions of both bodies are as on April 16, 2006; by April 2007 they had changed by about three pixels (~1 AU).
Orbit of Pluto — polar view. This 'view from above' shows how Pluto's orbit (in red) is less circular than Neptune's (in blue), and how Pluto is sometimes closer to the Sun than Neptune. The darker halves of both orbits show where they pass below the plane of the ecliptic. The positions of both bodies are as on April 16, 2006; by April 2007 they had changed by about three pixels (~1 AU).

Despite Pluto's orbit apparently crossing that of Neptune when viewed from directly above the ecliptic, the two objects cannot collide. This is because their orbits are aligned so that Pluto and Neptune can never approach closely. Several factors contribute to this. Image File history File links TheKuiperBelt_Orbits_Pluto_Polar. ... Image File history File links TheKuiperBelt_Orbits_Pluto_Polar. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... is the 106th day of the year (107th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...


At the simplest level, one can examine the two orbits and see that they do not intersect. When Pluto is closest to the Sun, and hence closest to Neptune's orbit as viewed in a top-down projection (right), it is also the farthest above the ecliptic. This means Pluto's orbit actually passes above that of Neptune, preventing a collision.[56] Indeed, the part of Pluto's orbit that lies as close or closer to the Sun than that of Neptune lies about 8 AU above the ecliptic,[57] and so a similar distance above Neptune's orbit.[58] Pluto's ascending node, the point at which the orbit crosses the ecliptic, is currently separated from Neptune's by over 21°;[59] their descending nodes are separated by a similar angular distance (see diagram). Since Neptune's orbit is almost flat with respect to the ecliptic, Pluto is far above it by the time the two orbits cross. The astronomical unit (AU or au or a. ... An orbital node is one of the two points where an inclined orbit crosses a plane of reference (e. ...


However, this alone is not enough to protect Pluto; perturbations from the planets, particularly Neptune, would adjust Pluto's orbit (e.g. orbital precession), so that over millions of years a collision could be possible. Some other effect(s) must therefore be in place. The most significant of these is a mean motion resonance with Neptune. Perturbation is a term used in astronomy to describe alterations to an objects orbit caused by gravitational interactions with other bodies. ... Precession redirects here. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ...

This diagram shows the relative positions of Pluto (red) and Neptune (blue) on selected dates. The size of Neptune and Pluto is depicted as inversely proportional to the distance between them to emphasise the closest approach in 1896.
This diagram shows the relative positions of Pluto (red) and Neptune (blue) on selected dates. The size of Neptune and Pluto is depicted as inversely proportional to the distance between them to emphasise the closest approach in 1896.

Pluto lies in the 3:2 mean motion resonance of Neptune: for every three orbits of Neptune around the Sun, Pluto makes two. The two objects then return to their initial positions and the cycle repeats, each cycle lasting about 500 years. This pattern is configured so that, in each 500-year cycle, the first time that Pluto is near perihelion Neptune is over 50° behind Pluto. By Pluto's second perihelion, Neptune will have completed a further one and a half of its own orbits, and so will be a similar distance ahead of Pluto. In fact, the minimum separation of Pluto and Neptune is over 17 AU; Pluto actually comes closer (11 AU) to Uranus than it does to Neptune.[58] Image File history File links TheKuiperBelt_Orbits_Pluto_Neptune2. ... Image File history File links TheKuiperBelt_Orbits_Pluto_Neptune2. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... For other uses, see Uranus (disambiguation). ...


The 3:2 resonance between the two bodies is highly stable, and is preserved over millions of years.[60] This prevents their orbits from changing relative to one another — the cycle always repeats in the same way — and so the two bodies can never pass near to each other. Thus, even if Pluto's orbit were not highly inclined, the two bodies could never collide.[58]


Other factors governing Pluto's orbit

diagram of the argument of perihelion
diagram of the argument of perihelion

Numerical studies have shown that over periods of millions of years, the general nature of the alignment between Pluto's and Neptune's orbits does not change.[56][61] However, there are several other resonances and interactions which govern the details of their relative motion, and enhance Pluto's stability. These arise principally from two additional mechanisms (in addition to the 3:2 mean motion resonance). Image File history File links Orbit. ... Image File history File links Orbit. ...


First, Pluto's argument of perihelion, the angle between the point where it crosses the ecliptic and the point where it is closest to the Sun, librates around 90°.[61] This means that when Pluto is nearest the Sun, it is at its farthest above the plane of the solar system, preventing encounters with Neptune. This is a direct consequence of the Kozai mechanism,[56] which relates the eccentricity of an orbit to its inclination, relative to a larger perturbing body — in this case Neptune. Relative to Neptune, the amplitude of libration is 38°, and so the angular separation of Pluto's perihelion to the orbit of Neptune is always greater than 52° (= 90°–38°). The closest such angular separation occurs every 10,000 years.[60] The argument of the perihelion is one of the orbital elements describing the orbit of a planet. ... Not to be confused with Liberation. ... In celestial mechanics, the Kozai mechanism is a secular perturbative effect resulting in the periodic sychronised changes of the eccentricity and the inclination of the orbit of the perturbed body. ...


Second, the longitudes of ascending node of the two bodies - the points where they cross the ecliptic - are in near-resonance with the above libration. When the two longitudes are the same —that is, when one could draw a straight line through both nodes and the Sun —Pluto's perihelion lies exactly at 90°, and it comes closest to the Sun at its peak above Neptune's orbit. In other words, when Pluto most closely intersects the plane of Neptune's orbit, it must be at its farthest beyond it. This is known as the 1:1 superresonance.[56]


To understand the nature of the libration, imagine a polar point of view, looking down on the ecliptic from a distant vantage point where the planets orbit counter-clockwise. After passing the ascending node, Pluto is interior to Neptune's orbit and moving faster, approaching Neptune from behind. The strong gravitational pull between the two causes angular momentum to be transferred to Pluto, at Neptune's expense. This moves Pluto into a slightly larger orbit, where it travels slightly slower, in accordance with Kepler's third law. As its orbit changes, this has the gradual effect of changing the pericentre and longitudes of Pluto (and, to a lesser degree, of Neptune). After many such repetitions, Pluto is sufficiently slowed, and Neptune sufficiently speeded up, that Neptune begins to catch Pluto at the opposite side of its orbit (near the opposing node to where we began). The process is then reversed, and Pluto loses angular momentum to Neptune, until Pluto is sufficiently speeded up that it begins to catch Neptune once again at the original node. The whole process takes about 20,000 years to complete.[58][60] A clockwise motion is one that proceeds like the clocks hands: from the top to the right, then down and then to the left, and back to the top. ... This gyroscope remains upright while spinning due to its angular momentum. ... Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...


Moons

Main article: Moons of Pluto
Pluto and its three known moons. Pluto and Charon are the bright objects in the center, the two smaller moons are at the right and bottom, farther out.
Pluto and its three known moons. Pluto and Charon are the bright objects in the center, the two smaller moons are at the right and bottom, farther out.
The Pluto system. The region around Pluto and Charon was reduced in brightness so that all four objects could be shown individually in a single image. Photo by David Tholen.
The Pluto system. The region around Pluto and Charon was reduced in brightness so that all four objects could be shown individually in a single image. Photo by David Tholen.

Pluto has three known natural satellites: Charon, first identified in 1978 by astronomer James Christy; and two smaller moons, Nix and Hydra, both discovered in 2005.[62] Hubble image of the Plutonian system Pluto has three known moons. ... Image File history File linksMetadata Download high-resolution version (1085x1095, 118 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Solar System Pluto User:Wahkeenah Plutos natural satellites Talk:Plutos natural satellites User:Appraiser User:JohnnyBGood... Image File history File linksMetadata Download high-resolution version (1085x1095, 118 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Solar System Pluto User:Wahkeenah Plutos natural satellites Talk:Plutos natural satellites User:Appraiser User:JohnnyBGood... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Charon (shair-ən or kair-ən (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... James Walter Christy (born 1938) is an American astronomer. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ...


The Plutonian moons are unusually close to Pluto, compared to other observed systems. Moons could potentially orbit Pluto up to 53% (or 69%, if retrograde) of the Hill sphere radius, the stable gravitational zone of Pluto's influence. For example, Psamathe orbits Neptune at 40% of the Hill radius. In the case of Pluto, only the inner 3% of the zone is known to be occupied by satellites. In the discoverers’ terms, the Plutonian system appears to be "highly compact and largely empty."[63] A Hill sphere approximates the gravitational sphere of influence of one astronomical body in the face of perturbations from another heavier body around which it orbits. ... Psamathe (sam-a-thee, Greek Ψαμαθεια, Latin PsamathÄ“) is an irregular natural satellite of Neptune. ...


Charon

The Pluto-Charon system is noteworthy for being the largest of the solar system's few binary systems, defined as those whose barycentre lies above the primary's surface (617 Patroclus is a smaller example).[64] This and the large size of Charon relative to Pluto has led some astronomers to call it a dwarf double planet.[65] The system is also unusual among planetary systems in that they are both tidally locked to each other: Charon always presents the same face to Pluto, and Pluto also always presents the same face to Charon. If one were standing on Pluto's near side, Charon would hover in the sky without moving; if one were to travel to the far side, one would never see Charon at all.[66] In 2007, observations by the Gemini Observatory of patches of ammonia hydrates and water crystals on the surface of Charon suggested the presence of active cryo-geysers.[67] In physics, the center of mass of a system of particles is a specific point at which, for many purposes, the systems mass behaves as if it were concentrated. ... 617 Patroclus is the second Jovian Trojan asteroid to be discovered. ... Pluto and Charon are sometimes informally considered to be a double (dwarf) planet. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ... The Gemini Observatory is an astronomical observatory consisting of two 8-metre telescopes at different sites. ...

Pluto and Charon, compared to Earth's Moon[1]
Name

(Pronunciation key)

Diameter (km) Mass (kg) Orbital radius (km)
(barycentric)
Orbital period (d)
Pluto /ˈpluːtəʊ/ 2306
(65% Moon)
1.305 (7)×1022
(18% Moon)
2,040 (100)
(0.6% Moon)
6.3872
(25% Moon)
Charon /ˈʃɛərən, ˈkɛərən/ 1205
(35% Moon)
1.52 (7)×1021
(2% Moon)
17,530 (90)
(5% Moon)

Charon (shair-ən or kair-ən (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ...

Nix and Hydra

Artist's concept of the surface of Hydra. Pluto with Charon (right) and Nix (bright dot on left).
Artist's concept of the surface of Hydra. Pluto with Charon (right) and Nix (bright dot on left).
Diagram of the Plutonian system. P 1 is Hydra, and P 2 is Nix.

Two additional moons of Pluto were imaged by astronomers working with the Hubble Space Telescope on May 15, 2005, and received provisional designations of S/2005 P 1 and S/2005 P 2. The International Astronomical Union officially named Pluto's newest moons Nix (or Pluto II, the inner of the two moons, formerly P 2) and Hydra (Pluto III, the outer moon, formerly P 1), on June 21, 2006.[68] Image File history File linksMetadata Download high resolution version (4000x3000, 1051 KB)The artists concept above shows the Pluto system from the surface of one of the candidate moons. ... Image File history File linksMetadata Download high resolution version (4000x3000, 1051 KB)The artists concept above shows the Pluto system from the surface of one of the candidate moons. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Image File history File links Pluto_system. ... Image File history File links Pluto_system. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... is the 135th day of the year (136th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ... is the 172nd day of the year (173rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...


These small moons orbit Pluto at approximately two and three times the distance of Charon: Nix at 48,700 kilometres and Hydra at 64,800 kilometres from the barycenter of the system. They have nearly circular prograde orbits in the same orbital plane as Charon, and are very close to (but not in) 4:1 and 6:1 mean motion orbital resonances with Charon.[69] Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ...


Observations of Nix and Hydra to determine individual characteristics are ongoing. Hydra is sometimes brighter than Nix, suggesting either that it is larger or that different parts of its surface may vary in brightness. Sizes are estimated from albedos. The moons' spectral similarity with Charon suggests a 35% albedo similar to Charon's; this results in diameter estimates of 46 kilometres for Nix and 61 kilometres for brighter Hydra. Upper limits on their diameters can be estimated by assuming the 4% albedo of the darkest Kuiper Belt objects; these bounds are 137 ± 11 km and 167 ± 10 km respectively. At the larger end of this range, the inferred masses are less than 0.3% that of Charon, or 0.03% of Pluto's.[70]


The discovery of the two small moons suggests that Pluto may possess a variable ring system. Small body impacts can create debris that can form into planetary rings. Data from a deep optical survey by the Advanced Camera for Surveys on the Hubble Space Telescope suggests that no ring system is present. If such a system exists, it is either tenuous like the Rings of Jupiter, or it is tightly confined to less than 1000 km in width.[71] A planetary ring is a ring of dust and other small particles orbiting around a planet in a flat disc-shaped region. ... Introduction The Advanced Camera for Surveys (ACS) is a third generation axial instrument aboard the Hubble Space Telescope (HST). ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... A schema of Jupiters ring system showing the four main components The rings of Jupiter are a system of planetary rings around the planet Jupiter. ...


In imaging the Plutonian system, observations from Hubble placed limits on any additional moons. With 90% confidence, no additional moons larger than 12 km (or a maximum of 37 km with an albedo of 0.041) exist beyond the glare of Pluto 5 arcseconds from the dwarf planet. This assumes a Charon-like albedo of 0.38; at a 50% confidence level the limit is 8 kilometres.[72]


Kuiper belt

Main article: Kuiper belt
Plot of all known Kuiper belt objects, set against the four outer planets
Plot of all known Kuiper belt objects, set against the four outer planets

Pluto's origin and identity have long puzzled astronomers. In the 1950s it was suggested that Pluto was an escaped moon of Neptune, knocked out of orbit by its largest current moon, Triton. This notion has been heavily criticised since, as explained above, Pluto never actually comes near the planet in its orbit.[73] The Kuiper belt, derived from data from the Minor Planet Center. ... Image File history File links Size of this preview: 611 × 599 pixelsFull resolution (2708 × 2656 pixel, file size: 314 KB, MIME type: image/png) Legend Red = The Sun Aquamarine = Giant Planet Green = Kuiper Belt Object Orange = Scattered Disk object or Centaur Pink = Trojan of Jupiter Yellow = Trojan of Neptune Axes... Image File history File links Size of this preview: 611 × 599 pixelsFull resolution (2708 × 2656 pixel, file size: 314 KB, MIME type: image/png) Legend Red = The Sun Aquamarine = Giant Planet Green = Kuiper Belt Object Orange = Scattered Disk object or Centaur Pink = Trojan of Jupiter Yellow = Trojan of Neptune Axes... Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ...


Beginning in 1992, astronomers began to discover a large population of small icy objects beyond Neptune that were similar to Pluto not only in orbit but also in size and composition. This belt, known as the Kuiper belt after one of the astronomers who first speculated on the nature of a trans-Neptunian population, is believed to be the source for many short-period comets. Astronomers now believe Pluto to be the largest of the Kuiper belt objects (KBOs). Like other KBOs, Pluto shares features in common with comets; the solar wind is gradually blowing Pluto's surface into space, in the manner of a comet.[74] If Pluto were placed near the Sun, it would develop a tail, as comets do.[75] The Kuiper belt, derived from data from the Minor Planet Center. ... Gerard Kuiper, circa 1963. ... The following is the IAUs list of periodic comets that have a number designation. ... The Kuiper belt (KYE per) is an area of the solar system extending from within the orbit of Neptune (at 30 AU) to 50 AU from the sun, at inclinations consistent with the ecliptic. ... Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small astronomical object similar to an asteroid but composed largely of ice. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


Though Pluto is the largest of the Kuiper belt objects discovered so far, Triton, which is slightly larger than Pluto, shares many atmospherical and geological composition similarities with Pluto and is believed to be a captured Kuiper belt object.[76] Eris (see below) is also larger than Pluto but is not strictly considered a member of the Kuiper belt population. Rather, it is considered a member of a linked population called the scattered disc. Eris, the largest known scattered disc object (center), and its moon Dysnomia (left of center). ...


A large number of Kuiper belt objects, like Pluto, possess a 3:2 orbital resonance with Neptune. KBOs with this orbital resonance are called "plutinos", after Pluto.[77] In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ...


Exploration of Pluto

Main article: New Horizons

Pluto presents significant challenges for spacecraft because of its small mass and great distance from Earth. Voyager 1 could have visited Pluto, but controllers opted instead for a close flyby of Saturn's moon Titan, which resulted in a trajectory incompatible with a Pluto flyby. Voyager 2 never had a plausible trajectory for reaching Pluto.[78] No serious attempt to explore Pluto via spacecraft occurred until the last decade of the 20th century. In August, 1992, JPL scientist Robert Staehle telephoned Pluto's discoverer, Clyde Tombaugh, requesting permission to visit his planet. "I told him he was welcome to it," Tombaugh later remembered, "though he's got to go one long, cold trip."[79] Despite this early momentum, in 2000, NASA cancelled the Pluto Kuiper Express mission, citing increasing costs and launch vehicle delays.[80] New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... Image File history File links Download high resolution version (1516x1696, 453 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (1516x1696, 453 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... is the 19th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... For the album by The Verve, see Voyager 1 (album). ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Trajectory Voyager 2 is an unmanned interplanetary spacecraft, launched on August 20, 1977. ... The JPL complex in Pasadena, Ca. ... The Pluto Kuiper Express mission, originally designated the Pluto Fast Flyby, was designed to fly by and make studies of the planet Pluto and its satellite Charon in 2012 and fly on to encounter one or more of the large bodies in the Kuiper belt beyond the orbit of Pluto. ...


After an intense political battle, a revised mission to Pluto, dubbed New Horizons, was granted funding from the US government in 2003.[81] New Horizons was launched successfully on January 19, 2006. The mission leader, S. Alan Stern, confirmed that some of the ashes of Clyde Tombaugh, who died in 1997, had been placed aboard the spacecraft.[82] New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... is the 19th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... S. Alan Stern is a planetary scientist at the Southwest Research Institute. ...


In early 2007 the craft made use of a gravity assist from Jupiter, and its closest approach to Pluto will be on July 14, 2015. Scientific observations of Pluto will begin 5 months prior to closest approach and will continue for at least a month after the encounter. New Horizons captured its first images of Pluto in late September 2006, during a test of the Long Range Reconnaissance Imager (LORRI).[83] The images, taken from a distance of approximately 4.2 billion kilometres, confirm the spacecraft's ability to track distant targets, critical for maneuvering toward Pluto and other Kuiper Belt objects. In orbital mechanics and aerospace engineering, a gravitational slingshot or gravity assist is the use of the gravity of a planet or other celestial body to alter the path and speed of a spacecraft. ... For other uses, see Jupiter (disambiguation). ... is the 195th day of the year (196th in leap years) in the Gregorian calendar. ... For the video game developer, see 2015, Inc. ...

First Pluto sighting from New Horizons
First Pluto sighting from New Horizons

New Horizons will use a remote sensing package that includes imaging instruments and a radio science investigation tool, as well as spectroscopic and other experiments, to characterise the global geology and morphology of Pluto and its moon Charon, map their surface composition and analyse Pluto's neutral atmosphere and its escape rate. New Horizons will also photograph the surfaces of Pluto and Charon. Image File history File links Download high-resolution version (900x900, 541 KB) (sourced from http://pluto. ... Image File history File links Download high-resolution version (900x900, 541 KB) (sourced from http://pluto. ...


Discovery of moons Nix and Hydra may present unforeseen challenges for the probe. With the relatively low escape velocity of Nix and Hydra, collisions with Kuiper belt debris may produce a tenuous dusty ring. Were New Horizons to fly through such a ring system, there would be an increased potential for micrometeorite damage that could potentially disable the probe.[71]


Planetary status controversy

See also: Definition of planet

Pluto's official status as a planet has been a subject of controversy since at least 1992, when the first Kuiper Belt Object, (15760) 1992 QB1, was discovered. Since then, further discoveries intensified the debate in the 21st century. Photograph of the planet Neptune and its moon Triton, taken by Voyager 2 as it entered the outer solar system. ... The Kuiper belt (KYE per) is an area of the solar system extending from within the orbit of Neptune (at 30 AU) to 50 AU from the sun, at inclinations consistent with the ecliptic. ... (15760) 1992 QB1 (also written (15760) 1992 QB1) was the first trans-Neptunian object to be discovered after Pluto and Charon. ...


Commemoration as a planet

Pluto is shown as a planet on the Pioneer plaque, an inscription on the space probes Pioneer 10 and Pioneer 11, launched in the early 1970s. The plaque, intended to give information about the origin of the probes to any alien civilization that might in the future encounter the vehicles, includes a diagram of our solar system, showing nine planets.[84] Similarly, an analog image contained within the Voyager Golden Record included on the probes Voyager 1 and Voyager 2 (also launched in the 1970s) includes data regarding Pluto and again shows it as the ninth planet.[85] The Disney character Pluto, introduced in 1930, was also named in honour of the planet.[86] In 1941, Glenn T. Seaborg named the newly created element plutonium in Pluto's honour, in keeping with the tradition of naming elements after newly discovered planets (uranium after Uranus, cerium after Ceres, palladium after Pallas, and neptunium after Neptune).[87] The illustration on the Pioneer plaque The Pioneer plaques are a pair of aluminum plaques which were placed on board the Pioneer 10 and Pioneer 11 spacecraft, featuring a pictorial message from humanity, in case either Pioneer 10 or 11 are intercepted by extraterrestrial beings. ... Pioneer 10 was the first spacecraft to travel through the asteroid belt, and was the first spacecraft to make direct observations of Jupiter. ... Position of Pioneer 10 and 11 Pioneer 11 was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. ... The Voyager Golden Record. ... For the album by The Verve, see Voyager 1 (album). ... Trajectory Voyager 2 is an unmanned interplanetary spacecraft, launched on August 20, 1977. ... Pluto (also known as Pluto the Pup) is an animated cartoon made famous in a series of Disney short cartoons. ... Glenn Theodore Seaborg (April 19, 1912 – February 25, 1999) won the 1951 Nobel Prize in Chemistry for discoveries in the chemistry of the transuranium elements,[1] contributed to the discovery and isolation of ten elements, developed the actinide concept and was the first to propose the actinide series which led... Look up element in Wiktionary, the free dictionary. ... This article is about the radioactive element. ... This article is about the chemical element. ... For other uses, see Uranus (disambiguation). ... General Name, Symbol, Number cerium, Ce, 58 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Standard atomic weight 140. ... Spectral type: G[8] Absolute magnitude: 3. ... For other uses, see Palladium (disambiguation). ... 2 Pallas (pal-us, Greek Παλλάς) was the first asteroid discovered after 1 Ceres. ... General Name, Symbol, Number neptunium, Np, 93 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery metallic Standard atomic weight (237) g·mol−1 Electron configuration [Rn] 5f4 6d1 7s2 Electrons per shell 2, 8, 18, 32, 22, 9, 2 Physical properties Phase solid Density (near r. ... For other uses, see Neptune (disambiguation). ...


New discoveries ignite debate

Earth Dysnomia (136199) Eris Charon (134340) Pluto (136472) 2005 FY9 (136108) 2003 EL61 (90377) Sedna (90482) Orcus (50000) Quaoar (20000) Varuna

Pluto compared to Eris, (136472) 2005 FY9, (136108) 2003 EL61, Sedna, Orcus, Quaoar, and Varuna compared to Earth (artist's impressions; no detailed photographs exist).
Pluto compared to Eris, (136472) 2005 FY9, (136108) 2003 EL61, Sedna, Orcus, Quaoar, and Varuna compared to Earth (artist's impressions; no detailed photographs exist).

The discovery of the Kuiper belt and Pluto's relation to it led many to question whether Pluto could be considered separately from others in its population. In 2002, the KBO 50000 Quaoar was discovered, with a diameter of roughly 1,280 kilometres, about half that of Pluto.[88] In 2004, the discoverers of 90377 Sedna placed an upper limit of 1,800 kilometres on its diameter, near Pluto's diameter of 2,320 kilometres.[89] Just as Ceres eventually lost its planet status after the discovery of the other asteroids, so, it was argued, Pluto should be reclassified as one of the Kuiper belt objects. Image File history File links Download high-resolution version (2750x1995, 1859 KB) Summary Comparison of the eight largest TNOs, based on the public domain NASA image: Image:2006-16-d-print. ... The Kuiper belt, derived from data from the Minor Planet Center. ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... you are abunch of bull | bgcolour=#FFFFC0 | name=90377 Sedna | image= | caption= Sedna is located in the center of the green circle | discovery=yes | discoverer=M. Brown, C. Trujillo, D. Rabinowitz | discovered=November 14, 2003 | mp_name=90377 Sedna | alt_names= | mp_category=Trans-Neptunian object | epoch=September 26, 1990 (JD 2448160. ... Spectral type: G[8] Absolute magnitude: 3. ... For other uses, see Asteroid (disambiguation). ...


On July 29, 2005, the discovery of a new Trans-Neptunian object was announced. Named Eris, it is now known to be slightly larger than Pluto.[90] This was the largest object discovered in the solar system since Triton in 1846. Its discoverers and the media initially called it the "tenth planet", although there was no official consensus at the time on whether to call it a planet or not.[91] Others in the astronomical community considered the discovery to be the strongest argument for reclassifying Pluto as a minor planet.[92] is the 210th day of the year (211th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... Absolute magnitude: −1. ... Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ...


The last remaining distinguishing features of Pluto were now its large moon, Charon, and its atmosphere; these characteristics are probably not unique to Pluto: several other Trans-Neptunian objects have satellites; and Eris' spectrum suggests that its surface has a composition similar to Pluto's.[93] It also possesses a moon, Dysnomia, discovered in September 2005. Trans-Neptunian object 2003 EL61 (nicknamed "Santa") has two moons (one of which is nicknamed "Rudolph") and is the fourth largest TNO behind Eris, Pluto, and 2005 FY9 (nicknamed "Easterbunny"). Charon (shair-ən or kair-ən (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Absolute magnitude: −1. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... (also written (136108) 2003 EL61), nicknamed Easter Bunny, is a large Kuiper belt object, roughly one-third the mass of Pluto, discovered by J. L. Ortiz et al. ... Absolute magnitude: −1. ... (also written (136472) 2005 FY9) is a very large Kuiper belt object, and one of the two largest among the population in the classical KBO orbits. ...


Museum and planetarium directors occasionally created controversy by omitting Pluto from planetary models of the solar system. Some omissions were intentional; the Hayden Planetarium reopened after renovation in 2000 with a model of 8 planets without Pluto. The controversy made headlines in the media at the time.[94] Hayden Planetarium is a public planetarium located on Central Park West, New York City, next to the famous American Museum of Natural History. ...


IAU decision to reclassify Pluto

The debate came to a head in 2006 with an IAU resolution that created an official definition for the term "planet". According to this resolution, there are three main conditions for an object to be considered a 'planet': The final definition left the solar system with eight planets, pictured above (not to scale) Displays the remaining eight planets with the celestial bodies that have now been designated as dwarf planets. ... The final definition left the solar system with eight planets, pictured above (not to scale) Displays the remaining eight planets with the celestial bodies that have now been designated as dwarf planets. ...

  1. The object must be in orbit around the Sun.
  2. The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium.
  3. It must have cleared the neighbourhood around its orbit.[95]

Pluto fails to meet the third condition, since its mass was only 0.07 times that of the mass of the other objects in its orbit (Earth's mass, by contrast, is 1.7 million times the remaining mass in its own orbit).[96][97] The IAU further resolved that Pluto be classified in the simultaneously created dwarf planet category, and that it act as prototype for a yet-to-be-named category of trans-Neptunian objects, in which it would be separately, but concurrently, classified. Sol redirects here. ... Hydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient which creates a pressure gradient force in the opposite direction. ... This article or section may be confusing or unclear for some readers, and should be edited to rectify this. ... Artists impression of Pluto (background) and Charon (foreground). ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ...


There has been some resistance amongst the astronomical community towards the reclassification.[98][99][100] Alan Stern, principal investigator with NASA's "New Horizons" mission to Pluto, has publicly derided the IAU resolution, stating that "the definition stinks, for technical reasons."[101] Stern's current contention is that by the terms of the new definition Earth, Mars, Jupiter, and Neptune, all of which share their orbits with asteroids, would be excluded.[102] His other claim is that, since less than 5 percent of astronomers voted for it, the decision was not representative of the entire astronomical community.[102] Marc W. Buie of the Lowell observatory has voiced his opinion on the new definition on his website and is one of the petitioners against the definition.[103] Others have supported the IAU. Mike Brown, the astronomer who discovered Eris, said "through this whole crazy circus-like procedure, somehow the right answer was stumbled on. It’s been a long time coming. Science is self-correcting eventually, even when strong emotions are involved."[104] This page may meet Wikipedias criteria for speedy deletion. ... The National Aeronautics and Space Administration (NASA) (IPA [ˈnæsÉ™]) is an agency of the United States government, responsible for the nations public space program. ... New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... Marc W. Buie is an astronomer at Lowell Observatory in Flagstaff, Arizona. ... Absolute magnitude: −1. ...


Among the general public, reception is mixed amidst widespread media coverage. Some have accepted the reclassification, while some are seeking to overturn the decision, with online petitions urging the IAU to consider reinstatement. A resolution introduced by some members of the California state assembly light-heartedly denounces the IAU for "scientific heresy," among other crimes.[105] The U.S. state of New Mexico's House of Representatives passed a resolution declaring that, in honour of Tombaugh, a longtime resident of that state, Pluto will always be considered a planet while in New Mexican skies, with March 13 being known as "Pluto Planet Day".[106] Others reject the change for sentimental reasons, citing that they have always known Pluto as a planet and will continue to do so regardless of the IAU decision.[107] Some observers view this rejection as an attempt to bend the rules in order to keep the only planet discovered by an American classified as such. [108] Capital Santa Fe Largest city Albuquerque Largest metro area Albuquerque metropolitan area Area  Ranked 5th  - Total 121,665 sq mi (315,194 km²)  - Width 342 miles (550 km)  - Length 370 miles (595 km)  - % water 0. ... is the 72nd day of the year (73rd in leap years) in the Gregorian calendar. ...


"Plutoed"

The verb "pluto" (preterite and past participle: "plutoed") is a neologism coined in the aftermath of the decision. In January 2007, the American Dialect Society chose "plutoed" as its 2006 Word of the Year, defining "to pluto" as "to demote or devalue someone or something", an example being "as happened to the former planet Pluto when the General Assembly of the International Astronomical Union decided Pluto no longer met its definition of a planet."[109][110] [111] The preterite (also praeterite, in American English also preterit, or past historic) is the grammatical tense expressing actions which took place in the past. ... In linguistics, a participle is a non-finite verb form that can be used in compound tenses or voices, or it can be used as a modifier. ... A neologism is a word, term, or phrase which has been recently created (or coined), often to apply to new concepts, to synthesize pre-existing concepts, or to make older terminology sound more contemporary. ... According to its web site, the American Dialect Society, founded in 1889, is dedicated to the study of the English language in North America, and of other languages, or dialects of other languages, influencing it or influenced by it. ...


Society president Cleveland Evans stated the reason for the organization's selection of "plutoed". "Our members believe the great emotional reaction of the public to the demotion of Pluto shows the importance of Pluto as a name. We may no longer believe in the Roman god Pluto, but we still have a sense of connection with the former planet", he said.[112] For other uses, see Pluto (disambiguation). ...


See also

Solar System Portal

Image File history File links Download high resolution version (1024x1274, 113 KB) Original caption released with image This is a montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars... Artists impression of Pluto and its tidally locked near-twin Charon. ... Planets in astrology have a different meaning to the modern astronomical understanding of what a planet is. ... The Sun disappears behind Charons surface during the total solar eclipse on Pluto of 23rd December 2111 Eclipses of the Sun on Pluto are caused when its natural satellite, Charon passes infront of the Sun, blocking its light. ... On August 24, 2006, the International Astronomical Union (IAU) decided to reclassify Pluto as a dwarf planet, requiring that a planet must clear the neighbourhood around its orbit. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ...

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arXiv (pronounced archive, as if the X were the Greek letter χ) is an archive for electronic preprints of scientific papers in the fields of physics, mathematics, computer science and quantitative biology which can be accessed via the Internet. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 83rd day of the year (84th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 72nd day of the year (73rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 72nd day of the year (73rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 72nd day of the year (73rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 307th day of the year (308th in leap years) in the Gregorian calendar. ... 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Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 178th day of the year (179th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 86th day of the year (87th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 13th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 102nd day of the year (103rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 288th day of the year (289th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 84th day of the year (85th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 308th day of the year (309th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 308th day of the year (309th in leap years) in the Gregorian calendar. ... Year 1994 (MCMXCIV) The year 1994 was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by the United Nations. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... This article is about the day. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 19th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 104th day of the year (105th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 84th day of the year (85th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 84th day of the year (85th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 88th day of the year (89th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 87th day of the year (88th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... This article is about the year. ... is the 42nd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 88th day of the year (89th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 83rd day of the year (84th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 117th day of the year (118th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... This article is about the day. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... This article is about the day. ... Also see: 2002 (number). ... is the 282nd day of the year (283rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 190th day of the year (191st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 102nd day of the year (103rd in leap years) in the Gregorian calendar. ... This page may meet Wikipedias criteria for speedy deletion. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 43rd day of the year in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 87th day of the year (88th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 90th day of the year (91st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 87th day of the year (88th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 107th day of the year (108th in leap years) in the Gregorian calendar. ... ... is the 305th day of the year (306th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 283rd day of the year (284th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 199th day of the year (200th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 172nd day of the year (173rd in leap years) in the Gregorian calendar. ... For information on Wikipedia press releases, see Wikipedia:Press releases. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 43rd day of the year in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 43rd day of the year in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 93rd day of the year (94th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 174th day of the year (175th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 174th day of the year (175th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 103rd day of the year (104th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 103rd day of the year (104th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 103rd day of the year (104th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 332nd day of the year (333rd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 221st day of the year (222nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... March 26 is the 85th day of the year (86th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 53rd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 228th day of the year (229th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 236th day of the year (237th in leap years) in the Gregorian calendar. ... is the 228th day of the year (229th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 145th day of the year (146th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... USA Today is a national American daily newspaper published by the Gannett Company. ... is the 6th day of the year in the Gregorian calendar. ... This article is about the year. ... is the 325th day of the year (326th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 335th day of the year (336th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 236th day of the year (237th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 103rd day of the year (104th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 305th day of the year (306th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 281st day of the year (282nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 7th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 7th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 20th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 10th day of the year in the Gregorian calendar. ...

External links

Find more information on Pluto by searching Wikipedia's sister projects
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  • Nunberg, G. (August 28, 2006). Dwarfing Pluto. NPR. An examination of the redefinition of Pluto from a linguistic perspective.
  • Pluto Profile by NASA's Solar System Exploration
  • Lowell Observatory (2007). Website of the observatory that discovered Pluto
  • Williams, D. R. (September 7, 2006). Pluto Fact Sheet. NASA.
  • Dunn, T. (2006). Pluto's 3:2 Resonance with Neptune. Gravity Simulator.
  • Fraknoi, A. (2006). Teaching What a Planet Is: A Roundtable on the Educational Implications of the New Definition of a Planet. Astronomy Education Review. Series of personal articles written by astronomers involved in the debate.
  • "plutoed" - entries in the Urban Dictionary
  • "pluto" v. - entries in the UrbanDictionary
 v  d  e The Solar System
The Sun Mercury Venus The Moon Earth Phobos and Deimos Mars Ceres The asteroid belt Jupiter Moons of Jupiter Saturn Moons of Saturn Uranus Moons of Uranus Moons of Neptune Neptune Moons of Pluto Pluto The Kuiper Belt Dysnomia Eris The Scattered Disc The Oort Cloud
The Sun · Mercury · Venus · Earth · Mars · Ceres · Jupiter · Saturn · Uranus · Neptune · Pluto · Eris
Planets · Dwarf planets · Moons: Terrestrial · Martian · Jovian · Saturnian · Uranian · Neptunian · Plutonian · Eridian
Small bodies:   Meteoroids · Asteroids/Asteroid moons (Asteroid belt) · Centaurs · TNOs (Kuiper belt/Scattered disc) · Comets (Oort cloud)
See also astronomical objects, the solar system's list of objects, sorted by radius or mass, and the Solar System Portal

Wikipedia does not have an article with this exact name. ... Image File history File links Wikibooks-logo. ... Image File history File links Wikiquote-logo. ... Image File history File links Wikisource-logo. ... Image File history File links Commons-logo. ... Image File history File links WikiNews-Logo. ... Image File history File links Wikiversity-logo-Snorky. ... Urban Dictionary is an online dictionary whose definitions are written by users. ... A screenshot of Urban Dictionarys front page Urban Dictionary is an online dictionary whose definitions are contributed by users. ... The planet Pluto has three known moons. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ... Image File history File links Pluto. ... This article is about the astronomical term. ... Artists impression of Pluto (background) and Charon (foreground). ... Photograph of the planet Neptune and its moon Triton, taken by Voyager 2 as it entered the outer solar system. ... The final definition left the solar system with eight planets. ... The Kuiper belt, derived from data from the Minor Planet Center. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... New Horizons on the launchpad New Horizons is a robotic spacecraft mission conducted by NASA. It is expected to be the first spacecraft to fly by and study the dwarf planet Pluto and its moons, Charon, Nix and Hydra. ... The Pluto Fast Flyby was a space mission meant to preform a flyby of the dwarf planet Pluto. ... The Pluto Kuiper Express mission, originally designated the Pluto Fast Flyby, was designed to fly by and make studies of the planet Pluto and its satellite Charon in 2012 and fly on to encounter one or more of the large bodies in the Kuiper belt beyond the orbit of Pluto. ... Percival Lowell (March 13, 1855 – November 12, 1916) was an author, mathematician, and esteemed astronomer who fueled speculation that there were canals on Mars, founded the Lowell Observatory in Flagstaff, Arizona, and formed the beginning of the work and theories that led to the discovery of Pluto 14 years after... Venetia Phair at age 11 Venetia Katherine Douglas Phair (née Burney) (born 1919) was the first person to suggest the name Pluto for the planet[1] discovered by Clyde W. Tombaugh in 1930. ... Roger Lowell Putnam (December 19, 1893 - November 24, 1972) was an American politician and businessman. ... An image of Clyde Tombaugh Clyde William Tombaugh (February 4, 1906 – January 17, 1997) was an American astronomer who discovered the dwarf planet Pluto in 1930. ... Artists impression of Pluto and its tidally locked near-twin Charon. ... The Sun disappears behind Charons surface during the total solar eclipse on Pluto of 23rd December 2111 Eclipses of the Sun on Pluto are caused when its natural satellite, Charon passes infront of the Sun, blocking its light. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... Artists impression of Pluto (background) and Charon (foreground). ... The Kuiper belt, derived from data from the Minor Planet Center. ... 90482 Orcus (originally known by the provisional designation 2004 DW) is a Kuiper Belt object (KBO) that was discovered by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. ... 28978 Ixion (IPA pronunciation: , Wiktionary:Ixion) is a Kuiper belt object discovered on May 22, 2001. ... The correct title of this article is (55637) 2002 UX25. ... 20000 Varuna (VAR oo na) is a large classical Kuiper Belt object (KBO). ... (55636) 2002 TX300 (Also written as (55636) 2002 TX300) is a large Trans-Neptunian object discovered in October 15, 2002 by the NEAT program. ... (also written (136108) 2003 EL61), nicknamed Easter Bunny, is a large Kuiper belt object, roughly one-third the mass of Pluto, discovered by J. L. Ortiz et al. ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... (also written (136472) 2005 FY9) is a very large Kuiper belt object, and one of the two largest among the population in the classical KBO orbits. ... is a trans-Neptunian object (TNO). ... Eris, the largest known scattered disc object (center), and its moon Dysnomia (left of center). ... (84522) 2002TC302 is a large Scattered Disk Object (SDO), orbiting the sun at a distance of 39. ... Absolute magnitude: −1. ... 2004 XR190 (also written 2004 XR190) is a newly discovered trans-Neptunian object located in the scattered disc. ... you are abunch of bull | bgcolour=#FFFFC0 | name=90377 Sedna | image= | caption= Sedna is located in the center of the green circle | discovery=yes | discoverer=M. Brown, C. Trujillo, D. Rabinowitz | discovered=November 14, 2003 | mp_name=90377 Sedna | alt_names= | mp_category=Trans-Neptunian object | epoch=September 26, 1990 (JD 2448160. ... Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ... Astronomical objects are significant physical entities, associations or structures which current science has confirmed to exist in space. ... This article is about the Solar System. ... Below is a list of solar system objects with diameter >500km: The Sun, a spectral class G2 star Mercury Venus Earth Moon Mars Jupiter Io Europa Ganymede Callisto complete list of Jupiters natural satellites Saturn Tethys Dione Rhea Titan Iapetus complete list of Saturns natural satellites Uranus Ariel... It has been suggested that Planetary-size comparison be merged into this article or section. ... This is a list of solar system objects by mass, in decreasing order. ... Pronunciation of Centaurs, Kuiper Belt Objects, and other planetoids of the outer solar system Pronunciation key ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... (15788) 1993 SB is a trans-Neptunian object of the Plutino class. ... (15789) 1993 SC is a trans-Neptunian object of the Plutino class. ... (15810) 1994 JR1, also written as 1994 JR1, is a Plutino, with 2:3 resonance with Neptune, similar to Pluto. ... (15820) 1994 TB is a trans-Neptunian object residing in the Kuiper belt. ... (20108) 1995 QZ9, also written (20108) 1995 QZ9, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (19299) 1996 SZ4 (also written (19299) 1996 SZ4) is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (15875) 1996 TP66, also written as (15875) 1996 TP66, is a trans-Neptunian object residing in the Kuiper belt. ... (118228) 1996 TQ66, also written (118228) 1996 TQ66, ia a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (24952) 1997 QJf, also written as 1997 QJ4 is as plutino, so it has a 2:3 resonance with Neptune, simalar to Pluto. ... (91133) 1998 HK151, also written as 1998 HK151 is a plutino, so it has a 2:3 resonance with Neptune, simalar to Pluto. ... (91205) 1998 US43, also written as a 1998 US43 is a plutino, so it has a 2:3 resonance with Neptune, simalar to Pluto. ... (33340) 1998 VG44 is a plutino, so it has a 2:3 resonance with Neptune, simalar to Pluto. ... (69986) 1998 WW24, also written as (69986) 1998 WW24, is a Trans-Neptunian object that resides in the Kuiper Belt. ... (69990) 1998 WU31, also written as (69990) 1998 WU31 is a TNO that resides in the Kuiper belt. ... 38083 Rhadamanthus (formerly known as (38083) 1999 HX11) is a trans-Neptunian object. ... (47171) 1999 TC36 (also written: (47171) 1999 TC36) is a trans-Neptunian object. ... 38628 Huya (original provisional designation: 2000 EB173) is a trans-Neptunian object. ... 28978 Ixion (IPA pronunciation: , Wiktionary:Ixion) is a Kuiper belt object discovered on May 22, 2001. ... (119951) 2002 KX14, also written as 2002 KX14, is a trans-Neptunian object (TNO) residing within the Kuiper belt. ... (also written (84719) 2002 VR128) is a trans-Neptunian object (TNO). ... is a trans-Neptunian object discovered by the Near Earth Asteroid Tracking program on November 14, 2003. ... 90482 Orcus (originally known by the provisional designation 2004 DW) is a Kuiper Belt object (KBO) that was discovered by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. ... 1993 RO is a trans-Neptunian object of the Plutino class. ... 1993 RP is a trans-Neptunian object of the Plutino class. ... , also written as 2003 AZ84, is a Trans-Neptunian object. ... 2001 QF298, also written as 2001 QF298, is a trans-Neptunian object that resides in the Kuiper belt. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ... (15760) 1992 QB1 (also written (15760) 1992 QB1) was the first trans-Neptunian object to be discovered after Pluto and Charon. ... (15807) 1994 GV9 is a trans-Neptunian object of the cubewano class. ... (16684) 1994 JQ1, also written as (16684) 1994 JQ1, is a trans-Neptunian object that resides in the Kuiper belt. ... (19255) 1994 VK8, also written as (19255) 1994 VK8, is a trans-Neptunian object (TNO) that resides in the Kuiper belt beyond Pluto. ... 1995 GJ with an inclination of 22. ... (24835) 1995 SM55, also written (24835) 1995 SM55, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (also written (19308) 1996 TO66) is a trans-Neptunian object. ... 58534 Logos, formerly known as (58534) 1997 CQ29, is a Kuiper belt object, more specifically a cubewano. ... (79360) 1997 CS29, also written as 1997 CS29, is a cubewano. ... (33001) 1997 CU29, also written as (33001) 1997 CU29 is a cubewano. ... (24978) 1998 HJ151, also written as (24978) 1998 HJ151, is a cubewano. ... (85627) 1998 HP151, also written as (85627) 1998 HP151 is a cubewano. ... (52747) 1998 HM151, also written as (52747} 1998 HM151, is a cubewano. ... (85633) 1998 KR65, also written as (85633) 1998 KR65, is a cubewano. ... 19521 Chaos (1998 WH24) is a cubewano, a Kuiper belt object not in resonance with any planet. ... (69987) 1998 WA25, also written as (69987) 1998 WA25, is a cubewano. ... (79983) 1999 DF9, also written as (79983) 1999 DF9, is a cubewano. ... (118378) 1999 HT11, also written as (118378) 1999 HT11, is a cubewano. ... 53311 Deucalion (original provisional designation: 1999 HU11) is a trans-Neptunian object. ... 20000 Varuna (VAR oo na) is a large classical Kuiper Belt object (KBO). ... is a trans-Neptunian object (TNO). ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... (55636) 2002 TX300 (Also written as (55636) 2002 TX300) is a large Trans-Neptunian object discovered in October 15, 2002 by the NEAT program. ... The correct title of this article is (55637) 2002 UX25. ... (also written (136108) 2003 EL61), nicknamed Easter Bunny, is a large Kuiper belt object, roughly one-third the mass of Pluto, discovered by J. L. Ortiz et al. ... (120178) 2003 OP32, also written as (120178) 2003 OP32,is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (90568) 2004 GV9 (also written (90568) 2004 GV9) is a trans-Neptunian object. ... (also written (136472) 2005 FY9) is a very large Kuiper belt object, and one of the two largest among the population in the classical KBO orbits. ... (145452) 2005 RN43, also written as (145452) 2005 RN43, is a large trans-Neptunian object (TNO) orbiting beyond Pluto in the Kuiper belt. ... 88611 Teharonhiawako (de-ha-loon-hee-a-wa-go, Mohawk approximately IPA: ), provisionally , is a trans-Neptunian object and a member of the Kuiper belt. ... 1998 WW31 (also written 1998 WW31) is an object of the solar system located beyond the orbit of Neptune. ... is a Trans-Neptunian object (TNO). ... 2003 MW12, also written 2003 MW12, is a trans-Neptunian object that is in the Kuiper belt. ... 2003 QW90, also written as 2003 QW90, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... While a Plutino completes 2 orbits around the Sun in the time it takes Neptune to complete 3 orbits, a Twotino makes 1 orbit around the Sun in the time it takes Neptune to complete 2 orbits. ... 1996 TR66, also written as 1996 TR66, is a Trans-Neptunian object orbiting beyond Pluto in the Kuiper belt. ... (26308) 1998 SM165, also written as (26308) 1998 SM165, is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (137295) 1999 RB216, also written as 1999 RB216, is a trans-Neptunian object that resides in the Kuiper belt. ... (130391) 2000 JG81, also written as 2000 JG81, is a trans-Neptunian object that resides in the Kuiper belt. ... 2002 WC19, also written as 2002 WC19, is a Trans-Neptunian object orbiting beyond Pluto. ... 1997 SZ10, also written as 1997 SZ10, is a trans-Neptunian object that resides in the Kuiper belt. ... In astronomy, a resonant Trans-Neptunian Object is a Trans-Neptunian Object (TNO) in mean motion orbital resonance with Neptune. ... (15809) 1998 JS is a trans-Neptunian object that resides in the Kuiper belt beyond Pluto. ... (15836) 1995 DA2, also written as (15836) 1995 DA2, is a trans-Neptunian object. ... (69988) 1998 WA31, also written as (69988) 1998 WA31, is a Trans-Neptunian object that resides in the scattered disc region beyond the Kuiper belt. ... (79969) 1999 CP133, also written as (79969) 1999 CP133, is a trans-Neptunian object. ... (26375) 1999 DE9 (also written (26375) 1999 DE9) is an object of the solar system located beyond the orbit of Neptune. ... (38084) 1999 HB12, also written as (38084) 1999 HB12, is a trans-Neptunian object that resides in the scattered disc region of the Solar System. ... (119068) 2001 KC77, also written as (119068) 2001 KC77, is a trans-Neptunian object (TNO) that resides in the scattered disc region of the Solar System. ... (119070) 2001 KP77 (better known as 2001 KP77) is a 4:7 resonant Trans-Neptunian object (TNO) located in the kuiper belt. ... (84522) 2002TC302 is a large Scattered Disk Object (SDO), orbiting the sun at a distance of 39. ... (136120) 2003 LG7, also written as 2003 LG7, is a trans-Neptunian object that resides in the Kuiper belt. ... Eris, the largest known scattered disc object (center), and its moon Dysnomia (left of center). ... Absolute magnitude: −1. ... (48639) 1995 TL8 (also written (48639) 1995 TL8) is a trans-Neptunian object of the Scattered disk object subclass, and posesses a very large satellite. ... (26181) 1996 GQ21, also written as (26181) 1996 GQ21, is a trans-Neptunian object that resides in the scattered disc region of the Solar System. ... (15874) 1996 TL66 is a trans-Neptunian object that resides in the Kuyper belt. ... (79978) 1999 CC158, also written as (79978) 1999 CC158, is a trans-Neptunian object that resides in the scattered disc region of the Solar System. ... (60608) 2000 EE173, also written as (60608) 2000 EE173, is a Trans-Neptunian object discovered in 2000 by N. Wyn Evans, Jane X. Luu and Chadwick A. Trujillo. ... 2000 OO67 is a Trans Neptunian Object notable for its highly eccentric orbit. ... (118702) 2000 OM67, also written as (118702) 2000 OM67, is a trans-Neptunian object (TNO) that resides in the scattered disc region of the Solar System. ... (42301) 2001 UR163, also written as (42301) 2001 UR163, is a trans-Neptunian object (TNO) that resides in the extended Scattered disc. ... (119878) 2002 CY224, also written as (119878) 2002 CY224, is a trans-Neptunian object (TNO) that resides in the scattered disc region of the Solar System. ... (95625) 2002 GX32, also written as (95625) 2002 GX32, is a trans-Neptunian object that resides in the scattered disc region of the Solar System. ... (65407) 2002 RP120 holds the dubious distinction of being the most eccentric of the numbered asteroids (as of July 2004). ... you are abunch of bull | bgcolour=#FFFFC0 | name=90377 Sedna | image= | caption= Sedna is located in the center of the green circle | discovery=yes | discoverer=M. Brown, C. Trujillo, D. Rabinowitz | discovered=November 14, 2003 | mp_name=90377 Sedna | alt_names= | mp_category=Trans-Neptunian object | epoch=September 26, 1990 (JD 2448160. ... (145451) 2005 RM43, also written as (145451) 2005 RM43, is a trans-Neptunian object that resides in the scattered disc region beyond the Kuiper belt. ... , also written as (148209) 2000 CR105, is the fourth most distant known object in the solar system after Eris, and Sedna. ... 2004 XR190 (also written 2004 XR190) is a newly discovered trans-Neptunian object located in the scattered disc. ... 2005 TN74 (also written 2005 TN74) is a possible Trojan asteroid of Neptune which was discovered by Scott S. Sheppard and Chadwick A. Trujillo in 2005. ... 2006 QH181, also written as 2006 QH181, is a trans-Neptunian object. ... (15883) 1997 CR29, also written as (15883) 1997 CR29, is a trans-Neptunian object. ... (35671) 1998 SN165, also written as (35671) 1998 SN165, is a trans-Neptunian object. ... (59358) 1999 CL158, also written as (59358) 1999 CL158, is a trans-Neptunian object that resides in the Kuiper belt. ... (118379) 1999 HC12, also written as (118379) 1999 HC12, is a trans-Neptunian object. ... (40314) 1999 KR16, also written as (40314) 1999 KR16, is a trans-Neptunian object. ... (86047) 1999 OY3, also written as (86047) 1999 OY3, is a trans-Neptunian object that resides in the Kuiper belt beyond Pluto. ... (120132) 2003 FY128, also written as (120132) 2003 FY128, is a trans-Neptunian object. ... (120347) 2004 SB60, also written as (120347) 2004 SB60, is a trans-Neptunian object that resides in the Kuiper belt. ... (120348) 2004 TY364, also written as (120348) 2004 TY364, is a trans-Neptunian object that resides in the Kuiper belt. ... (145453) 2005 RR43, also written as (145453) 2005 RR43, is a trans-Neptunian object (TNO). ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Hydra (formerly known as S/2005 P 1) is a natural satellite of Pluto. ... Nix (formerly known as S/2005 P 2), is a natural satellite of Pluto. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... 1998 WW31 (also written 1998 WW31) is an object of the solar system located beyond the orbit of Neptune. ... 2003 EL61 (also written 2003 EL61), is a large and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... 2003 EL61 (also written 2003 EL61), is a large and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... 58534 Logos, formerly known as (58534) 1997 CQ29, is a Kuiper belt object, more specifically a cubewano. ... (79360) 1997 CS29, also written as (79360) 1997 CS29, is a cubewano. ... (88611) Teharonhiawako I Sawiskera, or simply Sawiskera (za-wee-ske-la, Mohawk approximately IPA: ), is the moon of KBO 88611 Teharonhiawako, and about 2/3 the size of that body. ... Artists impression of Pluto (background) and Charon (foreground). ... Artists rendering of the Oort cloud and the Kuiper Belt. ... Pronunciation of Centaurs, Kuiper Belt Objects, and other planetoids of the outer solar system Pronunciation key ... This article is about the Solar System. ... Sol redirects here. ... This article is about the planet. ... For other uses, see Venus (disambiguation). ... This article is about Earth as a planet. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... Spectral type: G[8] Absolute magnitude: 3. ... For other uses, see Jupiter (disambiguation). ... This article is about the planet. ... For other uses, see Uranus (disambiguation). ... For other uses, see Neptune (disambiguation). ... Absolute magnitude: −1. ... This article is about the astronomical term. ... Artists impression of Pluto (background) and Charon (foreground). ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... This article is about Earths moon. ... The relative sizes of and distance between Mars, Phobos, and Deimos, to scale : Phobos (top) and Deimos (bottom). ... Jupiters 4 Galilean moons, in a composite image comparing their sizes and the size of Jupiter (Great Red Spot visible). ... The Saturnian system (photographic montage) Moons of Saturn (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ... Uranus has twenty-seven known moons. ... Neptune (top) and Triton (bottom), 3 days after the Voyager 2 flyby. ... Hubble image of the Plutonian system Pluto has three known moons. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... A Small Solar System Body (SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that are neither planets nor dwarf planets: [1] This encompasses: all minor planets apart from the dwarf planets, : the classical asteroids, (except for 1 Ceres, the... “Meteor” redirects here. ... For other uses, see Asteroid (disambiguation). ... 243 Ida and its moon Dactyl An asteroid moon is an asteroid that orbits another asteroid. ... For other uses, see Asteroid (disambiguation). ... The centaurs are a class of icy planetoids that orbit the Sun between Jupiter and Neptune, named after the mythical race of centaurs. ... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... The Kuiper belt, derived from data from the Minor Planet Center. ... Eris, the largest known scattered disc object (center), and its moon Dysnomia (left of center). ... Comet Hale-Bopp Comet West For other uses, see Comet (disambiguation). ... Artists rendering of the Oort cloud and the Kuiper Belt. ... Astronomical objects are significant physical entities, associations or structures which current science has confirmed to exist in space. ... Below is a list of solar system objects with diameter >500km: The Sun, a spectral class G2 star Mercury Venus Earth Moon Mars Jupiter Io Europa Ganymede Callisto complete list of Jupiters natural satellites Saturn Tethys Dione Rhea Titan Iapetus complete list of Saturns natural satellites Uranus Ariel... It has been suggested that Planetary-size comparison be merged into this article or section. ... This is a list of solar system objects by mass, in decreasing order. ...


  Results from FactBites:
 
Pluto - Wikipedia, the free encyclopedia (4782 words)
Pluto and its largest satellite Charon have often been considered a binary system because they are more nearly equal in size than any of the planet/moon combinations in the solar system, and because the barycentre of their orbits does not lie within either body.
Pluto's official status as a planet has been a constant subject of controversy, fueled by the past lack of a clear definition of planet, since at least as early as 1992, when the first Kuiper Belt Object, 1992 QB1, was discovered.
Pluto is shown as a planet on the Pioneer plaque, an inscription on the space probes Pioneer 10 and Pioneer 11, launched in the early 1970s.
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