This page is protected from moves until disputes have been resolved on the discussion page. The reason for its protection is listed at the list of protected pages. The page may still be edited but cannot be moved until unprotected. Protection is not an endorsement of the current page name (136199 Eris). You may also request unprotection.

136199 Eris

Eris (center) and Dysnomia (right of center). Keck Observatory.
Discovery A
Discoverer	M. E. Brown, C. A. Trujillo, D. L. Rabinowitz
Discovery date	October 21, 2003
Alternate designations B	2003 UB313
Category	Trans-Neptunian object (Scattered disc object)
Orbital elements C
Epoch March 6, 2006 (JD 2453800.5)
Eccentricity (e)	0.44177
Semi-major axis (a)	67.6681 AU (10.12 Tm)
Perihelion (q)	37.77 AU (5.65 Tm)
Aphelion (Q)	97.56 AU (14.60 Tm)
Orbital period (P)	203,500 d (557 a)
Mean orbital speed	3.436 km/s
Inclination (i)	44.187°
Longitude of the ascending node (Ω)	35.8696°
Argument of perihelion (ω)	151.4305°
Mean anomaly (M)	197.63427°
Physical characteristics D
Dimensions	2400 km ± 100 km
Mass	?×10? kg
Density	? g/cm³
Surface gravity	? m/s²
Escape velocity	? km/s
Rotation period	> 8 h?
Spectral class	?
Absolute magnitude	−1.12 ± 0.01
Albedo (geometric)	0.86 ± 0.07
Mean surface temperature	~30 K

Eris (IPA /ˈiɹɪs/ or /ˈɛɹɪs/), officially designated 136199 Eris, is the largest known dwarf planet in the solar system. Previously designated 2003 UB₃₁₃, it was initially nicknamed "Xena" by its discoverers. It is a trans-Neptunian object (TNO), orbiting the Sun in a region of space known as the scattered disc, just beyond the Kuiper belt, and accompanied by at least one moon, Dysnomia. Mike Brown, who led the Mount Palomar-based discovery team, announced in April 2006 that the Hubble Telescope has measured Eris's diameter to be 2400 km, slightly larger than that of Pluto.^[1] Image File history File links Padlock. ... Image File history File links Eris_and_dysnomia. ... The Mauna Kea Observatory, an institute of the University of Hawaii, is considered one of the most important land-based observatories in the world for its isolated, unobstructed views of space without interference from man-made light sources. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Chadwick A. Chad Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Kuiper belt and the outer solar system. ... David Lincoln Rabinowitz (born 1960) is a researcher at Yale University studying the Kuiper belt and the outer solar system. ... October 21 is the 294th day of the year (295th in leap years) in the Gregorian Calendar, with 71 days remaining. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Provisional designation of in astronomy is the naming convention applied to astronomical objects immediately following their discovery. ... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... A trans-Neptunian object (TNO) is any object in the solar system that orbits the sun at a greater distance on average than Neptune. ... A scattered disk object (or scattered disc object or SDO) is a trans-Neptunian object of the Kuiper belt with a very eccentric orbit. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... March 6 is the 65th day of the year in the Gregorian Calendar (66th in Leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the number of days that have elapsed since 12 noon Greenwich Mean Time (UT or TT) on Monday, January 1, 4713 BC in the proleptic Julian calendar . ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... The astronomical unit (AU or au or a. ... tera- (symbol: T) is a prefix in the SI system of units denoting 1012, or 1 000 000 000 000. ... metre or meter, see meter (disambiguation) A metre or meter[1] (symbol: m) is a unit of length and the current base unit of length in the International System of Units (SI). ... 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. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Water, Rabbit, and Deer: three of the 20 day symbols in the Aztec calendar, from the Aztec Sun Stone. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... 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. ... Look up second in Wiktionary, the free dictionary. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The Longitude of the ascending node () is one of the orbital elements used to specify the orbit of an object in space. ... The argument of the perihelion is one of the orbital elements describing the orbit of a planet. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... For the majority of numbered asteroids, almost nothing is known apart from a few physical parameters. ... Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... Gravity is a force of attraction that acts between bodies that have mass. ... In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... Asteroids are assigned a type based on spectral shape, color, and sometimes albedo. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us (in the absence of interstellar extinction!). It allows the overall brightnesses of objects to be compared without regard to distance. ... Albedo is a ratio of scattered to incident electromagnetic radiation power, most commonly light. ... The geometric albedo of an astronomical body is the ratio of its total brightness at zero phase angle to that of an idealised fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section. ... In thermodynamics, temperature is the physical property of a system that underlies the common notions of hot and cold —something that is hotter has the greater temperature. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... This is a list of numbered asteroids, in sequential order. ... In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ... Artists impression of Pluto (background) and its satellite Charon (foreground). ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... 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 Sun is the name given to the star of our solar system. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Palomar Observatory is a privately-owned observatory located in San Diego County, California, 90 miles (145 km) southeast of Mount Wilson Observatory, on Palomar Mountain. ... The Hubble Space Telescope (HST) is a telescope orbiting the Earth at the outer edges of the atmosphere. ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ...

Eris's size resulted in its discoverers and NASA labelling it the solar system's tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, stimulated the International Astronomical Union (IAU) to define the term "planet" more precisely. Under a new definition approved on August 24, 2006, Eris was designated a "dwarf planet".^[2] Brown has since stated his approval of the new "dwarf planet" label.^[3] NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... Ever since the discovery of Pluto, the existence of a tenth planet has been speculated by astronomers and the general public alike. ... Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... The planet Neptune and its moon Triton, taken by Voyager 2 as it entered the outer solar system The definition of planet has proven elusive despite the term being one of the best-known astronomical words. ... 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. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ...

Discovery

Animation showing the movement of Eris on the images used to discover it. Eris is located on the left side, slightly above the middle of the image. The three frames were taken over a period of three hours.

Eris was discovered by the team of Michael E. Brown, Chad Trujillo, and David Rabinowitz on January 5, 2005, from images taken on October 21, 2003. The discovery was announced on July 29, 2005, the same day as two other large TNOs, (136108) 2003 EL₆₁ and (136472) 2005 FY₉. The search team has been systematically scanning for large outer solar system bodies for several years, and had previously been involved in the discovery of several other very large TNOs, including 50000 Quaoar, 90482 Orcus, and 90377 Sedna. Image File history File links Animation of the images from which 2003 UB313 was discovered. ... Image File history File links Animation of the images from which 2003 UB313 was discovered. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Chadwick A. Chad Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Kuiper belt and the outer solar system. ... David Lincoln Rabinowitz (born 1960) is a researcher at Yale University studying the Kuiper belt and the outer solar system. ... January 5 is the 5th day of the year in the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... October 21 is the 294th day of the year (295th in leap years) in the Gregorian Calendar, with 71 days remaining. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... July 29 is the 210th day (211th in leap years) of the year in the Gregorian Calendar, with 155 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... (136108) 2003 EL61 (also written (136108) 2003 EL61), is a large (roughly one-third the mass of Pluto) and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... (136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object discovered on March 31, 2005 by the team led by Michael Brown. ... Artists impression by G. Bacon of STScI / NASA 50000 Quaoar (pronounced kwah·war, kwah·wor, or kwow·ur, Tongva ) [1] is a Trans-Neptunian object orbiting the Sun in the Edgeworth-Kuiper belt. ... 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. ... 90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. ...

Routine observations were taken by the team on October 21, 2003, using the 48-inch (122 cm) Samuel Oschin reflecting telescope at Mount Palomar Observatory, California, but the object captured on the images was not discovered at that point due to its very slow motion across the sky: the team's automatic image-searching software excluded all objects moving at less than 1.5 arcseconds per hour to reduce the number of false positives returned. When 90377 Sedna was discovered, it was moving at 1.75 arcsec/h, and in light of that the team reanalyzed their old data with a lower limit on the angular motion, sorting through the false positives by eye. In January 2005, the re-analysis revealed Eris' slow motion against the background stars. October 21 is the 294th day of the year (295th in leap years) in the Gregorian Calendar, with 71 days remaining. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... The Samuel Oschin telescope is a 48-inch (1. ... Ritchey 24 reflecting telescope A reflecting telescope (reflector) is an optical telescope which uses a combination of curved and plane (flat) mirrors to reflect light and form an image, rather than lenses to refract or bend light to form an image. ... Palomar Observatory is a privately-owned observatory located in San Diego County, California, 90 miles (145 km) southeast of Mount Wilson Observatory, on Palomar Mountain. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... A false positive, also called false alarm, exists when a test reports, incorrectly, that it has found a signal where none exists in reality. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ...

Follow-up observations were then carried out to make a preliminary determination of its orbit, which allowed its distance and size to be estimated. The team had planned to delay announcing their discovery until further observations had been made which would have allowed more accurate determinations of the body's size and mass, but were forced to bring forward the announcement when the discovery of another object they had been tracking (2003 EL₆₁) was announced by another group in Spain. Brown's group later accused the Spanish group of a serious breach of ethics in connection with the discovery of 2003 EL₆₁ and asked that they be stripped of credit for its discovery (see the 2003 EL₆₁ or Michael E. Brown articles for details). In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... 2003 EL61 (also written 2003 EL61), nicknamed Santa (non-official designation), 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), nicknamed Santa (non-official designation), is a large and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ...

Yet more observations released in October 2005 revealed that the object had a moon, Dysnomia, nicknamed "Gabrielle" at the time. Scientists plan to use this information to determine the mass of Eris.
Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... For the singer Gabrielle, please see Gabrielle (singer) Gabrielle is also a speculative name for the recently-discovered 2003 UB313s moon, S/2005 (2003 UB313) 1. ...

Classification

Distribution of trans-Neptunian Objects.

Eris is classified as a dwarf planet and a scattered disk object (SDO).^[4]The latter is a category of the trans-Neptunian objects that are believed to have been "scattered" from the Kuiper belt into more distant and unusual orbits following gravitational interactions with Neptune as the solar system was forming. Although its high orbital inclination is unusual among the known SDOs, theoretical models suggest that objects that were originally near the inner edge of the Kuiper belt are scattered into orbits with higher inclinations than objects from the outer belt. Inner-belt objects are expected to be generally more massive than outer-belt objects, and so astronomers expect to discover more large objects like Eris in high-inclination orbits. Image File history File links TheTransneptunians_73AU.svg // Summary (voir plus loin pour la description en français) The distribution and classification of the trans-Neptunian Objects. ... Image File history File links TheTransneptunians_73AU.svg // Summary (voir plus loin pour la description en français) The distribution and classification of the trans-Neptunian Objects. ... Artists impression of Pluto (background) and its satellite Charon (foreground). ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ...

As Eris is larger than Pluto, it was initially described as the "tenth planet" by NASA and in media reports of its discovery. In response to the uncertainty over its status, and because of continuing debate over whether Pluto should be classified as a planet, the IAU delegated a group of astronomers to develop a new definition of the term planet. This definition was clarified under the new International Astronomical Union definition of a planet, adopted on 24 August 2006. Eris has been termed a dwarf planet by the IAU. It may also be under consideration as a member of "a new class of trans-Neptunian objects" yet to be defined by that body. It is not, however, considered to be a planet. Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... The planet Neptune and its moon Triton, taken by Voyager 2 as it entered the outer solar system The definition of planet has proven elusive despite the term being one of the best-known astronomical words. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... Artists impression of Pluto (background) and its satellite Charon (foreground). ...

Name

Eris (ca. 520 BC)

136199 Eris is named after the goddess Eris (Greek Ἔρις"), a personification of strife and discord.^[5] This name was assigned on September 13, 2006 following an unusually long period in which it was best known by the provisional designation 2003 UB₃₁₃, granted automatically according to the International Astronomical Union's naming protocols for minor planets. The delay in assigning a name was due to uncertainty over whether the nomenclature of the object should reflect prior practices associated with planetary nomenclature or the procedures applied to asteroids and other minor planets.^[6] The permanent name was assigned within a few weeks of the August 24, 2006 IAU ruling defining it as a dwarf planet.^[7] The name in part reflects the discord in the astronomy community caused by the debate over the object's nature.^[8] Image File history File linksMetadata Eris_(Discordia). ... Image File history File linksMetadata Eris_(Discordia). ... Eris (ca. ... September 13 is the 256th day of the year (257th in leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The provisional designation of comets and asteroids are similar to each other: they both follow a pattern set in 1925 by the Minor Planet Center of the IAU. Historical designations At first, astronomers strove to assign symbols to the minor planets: 1 Ceres a stylized sickle 2 Pallas a lozenge... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... Our solar system: the Sun, the eight planets and the three dwarf planets. ... An asteroid is a predominantly rocky body that orbits around its star. ... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... 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. ... Artists impression of Pluto (background) and its satellite Charon (foreground). ...

Unofficial names used in popular media for the object included:

• "Lila", a misunderstanding of planetlila, which forms part of the URL of the discovery web page, named after Michael E. Brown's daughter, Lilah.
• "Xena", an informal name used by the discovery team, inspired by the television series Xena: Warrior Princess. This name was reportedly saved for the first body discovered that was larger than Pluto. The team has said that they chose the name because "We have always wanted to name something Xena",^[9] apparently implying that the name was chosen without any reference to Planet X.

These names were not among those proposed to the IAU. Brown's speculation on the name to be given the object included Persephone (already used for the asteroid 399 Persephone),^[10] or a name from a figure in the creation mythology of an unspecified tradition.^[11] It appears that Brown's proposals along these lines were not accepted, and that the name Eris represents a new approach under different rules.^[12] A Uniform Resource Locator (URL) is a Uniform Resource Identifier which, “in addition to identifying a resource, [provides] a means of locating the resource by describing its primary access mechanism (e. ... Xena. ... Planet X is a large hypothetical planet orbiting beyond the orbit of Neptune. ... Persephone, the Maiden: the late Archaic Kore of Antenor from the Acropolis, Athens In Greek mythology, Persephone (Greek Περσεφόνη, Persephónē) was the queen of the Underworld, the Kore or young maiden, and the daughter of Demeter. ... 399 Persephone is a typical Main belt asteroid. ...

Orbit

Position of Eris on 29 July 2005. On the left is the view from "above" the plane of the solar system, while on the right is the view from "in front". Darker blue indicates the part of the orbit below the ecliptic plane. Also shown are Saturn, Uranus, Neptune, and Pluto.

Eris has an orbital period of 556.7 years, and currently lies at almost its maximum possible distance from the Sun (aphelion). It is currently the most distant known solar system object from the Sun at a distance of roughly 97 AU. Its semimajor axis is 67.669 astronomical units, its perihelion distance is 37.78 AU, and its aphelion distance is 97.56 AU. Approximately forty known TNOs (most notably 2000 OO₆₇ and Sedna), while currently closer to the Sun than Eris, have greater average orbital distances.^[13] Image File history File links Orbit of 2003 UB313 on 29 July 2005 (NASA) source: http://neo. ... Image File history File links Orbit of 2003 UB313 on 29 July 2005 (NASA) source: http://neo. ... July 29 is the 210th day (211th in leap years) of the year in the Gregorian Calendar, with 155 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... The Sun is the name given to the star of our solar system. ... The astronomical unit (AU or au or a. ... 2000 OO67 is a Trans Neptunian Object notable for its highly eccentric orbit. ... 90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. ...

Its orbit is highly eccentric, and brings it to within 37.8 AU of the Sun (a typical perihelion for scattered objects), still safe from direct interaction with Neptune (at ~30 AU). For comparison, Pluto, like other plutinos, follows a less inclined and less eccentric orbit and, protected by orbital resonance, it can cross Neptune’s orbit. Unlike the terrestrial planets and gas giants, whose orbits all lie roughly in the same plane as the Earth's, Eris' orbit is very inclined — it is tilted at an angle of about 44 degrees to the ecliptic. (This page refers to eccitricity in astrodynamics. ... The Sun is the name given to the star of our solar system. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... A terrestrial planet or telluric planet is a planet which is primarily composed of silicate rocks. ... A gas giant is a large planet that is not composed mostly of rock or other solid matter. ... Two intersecting planes in R3 In mathematics, a plane is a fundamental two-dimensional object. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...

The object currently has an apparent magnitude of about 19, making it bright enough to be detectable even in some amateur telescopes. While it would be a difficult object to spot visually, a telescope with an 8" lens or mirror and a CCD can image Eris in dark skies.^[14] The reason it had not been noticed until now is because of its steep orbital inclination: most searches for large outer solar system objects concentrate on the ecliptic plane, in which most solar system material is found. // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... 50 cm refracting telescope at Nice Observatory. ... A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...

Size

Optical measurement from HST pictures

The diameter of Eris has been measured to be 2400 km using images from the Hubble Space Telescope. The brightness of an object depends both on its size and the amount of light it reflects (its albedo). At a distance of 67 AU, an object with a radius of 3000 km would have an angular size of 40 milliarcseconds, which is directly measurable with HST; although resolving such small objects is at the very limit of Hubble's capabilities,^[15] sophisticated image processing techniques such as deconvolution can be used to measure such angular sizes fairly accurately.^[16] Diameter is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. ... Albedo is a ratio of scattered to incident electromagnetic radiation power, most commonly light. ... Angular size is a measurement of how large or small something is using rotational measurement (degrees of arc, arc_minutes, and arc-seconds). ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... Deconvolution is a process used to reverse the effects of convolution on recorded data. ...

Eris compared to Pluto, 2005 FY₉, 2003 EL₆₁, Sedna, Orcus, Quaoar, Varuna, and Earth.

This revised estimate of the diameter makes Eris only 4% larger than Pluto (According to Hubble, Eris' diameter measures 2,397 km (1,490 mi), give or take 100 km (60 mi). Pluto is about 2,306 km (1,433 mi) across. It also indicates that the albedo is 0.86, higher than any other large body in the Solar system other than Enceladus. It is speculated that the high albedo is due to the surface ices being replenished due to temperature fluctuations as Eris' eccentric orbit takes it closer and farther from the Sun. 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. ... 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. ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... (136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object discovered on March 31, 2005 by the team led by Michael Brown. ... (136108) 2003 EL61 (also written (136108) 2003 EL61), is a large (roughly one-third the mass of Pluto) and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... 90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) 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. ... Artists impression by G. Bacon of STScI / NASA 50000 Quaoar (pronounced kwah·war, kwah·wor, or kwow·ur, Tongva ) [1] is a Trans-Neptunian object orbiting the Sun in the Edgeworth-Kuiper belt. ... 20000 Varuna (VAR oo na) is a Kuiper Belt object about 1060 km in diameter, estimated from a combination of thermal and optical measurements. ... Earth (often referred to as the Earth, or the earth) whose Latin name is Tellus (often incorrectly referred to as Terra, meaning soil) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... [5] Atmospheric characteristics Pressure trace, significant spatial variability [6], [7] Water vapour 91% [8] Carbon dioxide 3. ...

Thermal measures

Previous observations of the thermal emission of Eris at a wavelength of 1.2 mm, where the object's brightness depends only on temperature and surface area, indicated a diameter of 3000⁺²⁷⁰_-100 km, about a third larger than Pluto.^[17] If the object rotates quickly, resulting in a more even heat distribution and a temperature of 23 to 24 kelvins, a likely diameter would be in the higher portion of the range (best fit 3090 km); if it rotates slowly, the visible surface would be warmer (about 27 K) and a likely diameter would be in the smaller end of the range (best fit 2860 km). The 2860 km figure implies a Pluto-like albedo of 60%, consistent with its Pluto-like spectral signature. The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ...

Possible explanation of the inconsistent results

The apparent inconsistence of the HST PSF results (2400 ± 100 km) with the above IRAM results (3000 ± 370 km) will be certainly studied in more length. Brown explains it by a slightly lower magnitude than the one assumed by Bertoldi (−1.12 ± 0.01 versus −1.16 ± 0.1, resulting by itself in almost 100 km difference in diameter). Assuming further the highest diameter (2500 km) and pole-on position of the object^[18] the difference between the results would appear consistent with 1.1-σ error margin. In probability and statistics, the standard deviation is a measure of the mean distance of values in a data set from their mean. ...

Another possible explanation for the IRAM results is offered by the Max-Planck Institut für Radioastronomie. The ratio between the bolometric albedo (representing the total reflected energy and used in the thermal method) and the geometric albedo (representing the reflection in some visual wavelength and used to calculate the diameter from HST pictures) is not known with high precision and depends on many factors. By itself, this uncertainty could bridge the gap between the two measures.^[17] The Institut de radioastronomie millimétrique (IRAM) operates two observatories at millimetre wavelengths, which are open to the international astronomical community: The 30-m single-dish telescope on Pico Veleta (2850 m), located in Sierra Nevada (Spain), and the six-antenna interferometer on the Plateau de Bure (2550 m) in... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standardized distance away. ...

Surface

The infrared spectrum of Eris, compared to that of Pluto, shows the marked similarities between the two bodies. Arrows denote methane absorption lines.

The discovery team followed up their initial identification of Eris with spectroscopic observations made at the 8 m Gemini North Telescope in Hawaiʻi on January 25, 2005. Infrared light from the object revealed the presence of methane ice, indicating that the surface of Eris is rather similar to Pluto, which was the only TNO already known to show the presence of methane. Neptune's moon Triton is probably related to Kuiper Belt objects, and also has methane on its surface. Image File history File links Near infrared spectrum of possible new planet 2003 UB313, taken with the Gemini 8m telescope. ... Image File history File links Near infrared spectrum of possible new planet 2003 UB313, taken with the Gemini 8m telescope. ... The simplest hydrocarbon, methane, is a gas (at standard temperature and pressure (STP)) with a chemical formula of CH4. ... High resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines). ... The Gemini Observatory is an astronomical observatory consisting of 8-metre telescopes at two different sites. ... This article or section does not cite its references or sources. ... January 25 is the 25th day of the year in the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The simplest hydrocarbon, methane, is a gas (at standard temperature and pressure (STP)) with a chemical formula of CH4. ... Triton (trye-tÉ™n, IPA , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ...

Unlike the somewhat reddish Pluto and Triton, however, Eris appears almost grey. Pluto's reddish color is believed to be due to deposits of tholins on its surface, and where these deposits darken the surface, the lower albedo leads to higher temperatures and the evaporation of methane deposits. In contrast, Eris is far enough away from the Sun that methane can condense onto its surface even where the albedo is low. The condensation of methane uniformly over the surface reduces any albedo contrasts and would cover up any deposits of red tholins. Tholin is a heteropolymer formed by solar ultraviolet irradiation of simple organic compounds such as methane or ethane. ... Condensation is the change in matter1 of a substance to a denser phase, such as a puppy gas (or vapor) to a liquid. ...

Methane is very volatile and its presence shows either that Eris has always resided in the distant reaches of the solar system where it is cold enough for methane ice to persist, or that it has an internal source of methane to replenish gas that escapes from its atmosphere. This contrasts with observations of another recently discovered trans-Neptunian object, 2003 EL₆₁, which reveal the presence of water ice but not methane. Volatile is the name of more than one concept: A financial instrument with high volatility is considered volatile in economics. ... 2003 EL61 (also written 2003 EL61), nicknamed Santa (non-official designation), is a large and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... Impact of a drop of water. ...

Atmosphere

Even though Eris can be up to three times further from the Sun than Pluto, it approaches close enough that some of the various ices that exist on the surface might become warm enough to sublimate and form a fine atmosphere; however, it is unclear whether this actually happens on Eris. Sublimation of an element or substance is a conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage. ...

Due to its orbit, surface temperatures vary between about −232 and −248 degrees Celsius.

Moon

Main article: Dysnomia (moon)

During 2005, the adaptive optics team at the Keck telescopes in Hawaii carried out observations of the four brightest trans-Neptunian object (Pluto, 2005 FY₉, 2003 EL₆₁, and Eris, using the newly commissioned laser guide star adaptive optics system. Observations taken on September 10 revealed a moon in orbit around Eris, which received its name (Dysnomia) at the same time as its primary. In keeping with the "Xena" nickname already in use for Eris, the moon was previously nicknamed Gabrielle by its discoverers, after the television warrior princess's sidekick. The name Dysnomia is taken from a mythological demon of lawlessness who was Eris' daughter; this is also an acknowledgement of the former nicknames, as the character of Xena was played by Lucy Lawless. Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... A deformable mirror can be used to correct wavefront errors in an astronomical telescope. ... The W. M. Keck Observatory is home to the two largest optical/near-infrared telescopes at the 4,145 meter (13,600 ft) summit of Mauna Kea in Hawaii. ... This article or section does not cite its references or sources. ... Lick Observatory laser guide star, built by LLNL. Laser guide stars are a form of artificial star created for use in astronomical adaptive optics imaging. ... September 10 is the 253rd day of the year (254th in leap years). ... Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ... Dysnomia (officially designated (136199) Eris I Dysnomia) is a moon of the dwarf planet Eris. ... Lucy Lawless as Xena on Xena: Warrior Princess, holding her characters trademark chakram. ...

See also

• Astronomical naming conventions
• Definition of planet (for the major points of debate on the definition of a "planet")
• International Astronomical Union (International body responsible for naming planets)
• Minor planet
• Planet (for the generally accepted definition)
• Planet X
• Tenth planet

In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ... The planet Neptune and its moon Triton, taken by Voyager 2 as it entered the outer solar system The definition of planet has proven elusive despite the term being one of the best-known astronomical words. ... Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... Our solar system: the Sun, the eight planets and the three dwarf planets. ... Planet X is a large hypothetical planet orbiting beyond the orbit of Neptune. ... Ever since the discovery of Pluto, the existence of a tenth planet has been speculated by astronomers and the general public alike. ...

References

• M. E. Brown, C. A. Trujillo, D. L. Rabinowitz Discovery of a Planetary-sized Object in the Scattered Kuiper Belt, The Astrophysical Journal, 635 (Dec. 2005), Issue 1, pp. L97-L100. Preprint on arXiv. DOI:10.1086/499336
• M. E. Brown, E.L. Schaller, H.G. Roe, D. L. Rabinowitz, C. A. Trujillo Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope To appear in The Astronomical Journal. Preprint (pdf) on Brown's site. DOI:10.1086/504843
• J. Licandro, W.M. Grundy, N. Pinilla-Alonso, J. de Leon Visible spectroscopy of 2003 UB313: Evidence for N2 ice on the surface of the largest TNO?. Accepted in A&A. Preprint on arXiv.
• M. E. Brown, M. A. van Dam, A. H. Bouchez, D. LeMignant, C. A. Trujillo, R. Campbell, J. Chin, Conrad A, .S. Hartman, E. Johansson, R. Lafon, D. L. Rabinowitz, P. Stomski, D. Summers, P. L. Wizinowich Satellites of the largest Kuiper belt objects, The Astrophysical Journal (2006), 639, Issue 1, pp. L43-L46. Preprint on arXiv. DOI:10.1086/501524
• Gomes R. S., Gallardo T., Fernández J. A., Brunini A. (2005), On the origin of the High-Perihelion Scattered Disk: the role of the Kozai mechanism and mean motion resonances, Celestial Mechanics and Dynamical Astronomy, Vol. 91, pp. 109-129 DOI:10.1007/s10569-004-4623-y
• Bertoldi F., Altenhoff W., Weiss A., Menten K. M., Thum C. (2006). The trans-neptunian object UB₃₁₃ is larger than Pluto, Nature, 2 February 2006;439(7076):563-4 DOI:10.1038/nature04494
• M. E. Brown and C. A. Trujillo Direct Measurement of the Size of the Large Kuiper Belt Object (50000) Quaoar The Astronomical Journal, 127 (2004), pages 2413 – 2417 DOI:10.1086/382513 Reprint (pdf) on Brown's site. Describing in detail the method applied to the recent measure of 2003 UB₃₁₃
• SpaceDaily Report on IAU Draft Definition of Planets and Plutons
• IAU Circular 8747 - Official publication of the IAU reporting the naming of Eris and Dysnomia (PDF file)

Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... David Lincoln Rabinowitz (born 1960) is a researcher at Yale University studying the Kuiper belt and the outer solar system. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... David Lincoln Rabinowitz (born 1960) is a researcher at Yale University studying the Kuiper belt and the outer solar system. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... David Lincoln Rabinowitz (born 1960) is a researcher at Yale University studying the Kuiper belt and the outer solar system. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... February 2 is the 33rd day of the year in the Gregorian Calendar. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... Dr. Michael (Mike) E. Brown has been an associate professor of planetary astronomy at the California Institute of Technology (Caltech) since 2002. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... IAU is a three-letter acronym that denotes: International Astronomical Union International American University International Association of Universities International Association of Ultra Runners for ultramarathoners. ...

Notes

IAU is a three-letter acronym that denotes: International Astronomical Union International American University International Association of Universities International Association of Ultra Runners for ultramarathoners. ... A news release, press release or press statement is a written or recorded communication directed at members of the news media for the purpose of announcing something claimed as having news value. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... August 16 is the 228th day of the year (229th in leap years) in the Gregorian Calendar. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... August 1 is the 213th day of the year in the Gregorian Calendar (214th in leap years), with 152 days remaining. ... August 24 is the 236th day of the year in the Gregorian Calendar (237th in leap years), with 129 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... Introduction The Advanced Camera for Surveys (ACS) is a third generation axial instrument aboard the Hubble Space Telescope (HST). ... The point spread function (PSF) defines the propagation of electromagnetic radiation from a point source. ...

External links

• Michael Brown's webpage about 2003 UB₃₁₃
• Brown's webpage about 2003 UB₃₁₃'s satellite
• compiled list of data
• MPEC listing for 2003 UB₃₁₃
• Java 3D orbit visualization
• Spaceflight Now article about 2003 UB₃₁₃, 2003 EL₆₁, and 2005 FY₉
• Slacker Astronomy Interview With Co-Discoverer Trujillo
• NASA - new planet discovered
• Trans-Neptunian Object 2003 UB₃₁₃ — IAU statement regarding the planetary status of 2003 UB₃₁₃
• Simulation of 2003 UB₃₁₃'s orbit — 2003 UB₃₁₃ is in a 17:5 resonance with Neptune
• Keck observatory page about the discovery of 2003 UB₃₁₃'s moon
• Parade Magazine on the spacecraft New Horizons
• M. E. Brown et al., Satellites of the largest Kuiper belt objects, Astrophysics Journal Letters, December 25, 2005 preprint

December 25 is the 359th day of the year (360th in leap years) in the Gregorian Calendar, with 6 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...

Observatories involved

• Keck Observatory, Hawaiʻi, US
• Palomar
• Gemini
• IRAM (Institut de Radio Astronomie Millimétrique Institut for Milimetric Radio Astronomy): French-German (Max-Planck Institut fur Radioastronomy, Bonn) and Spanish (where the 30 m telescope is situated) collaborative programme.
• HST

Press releases

• Gemini Observatory Shows That "10th Planet" Has a Pluto-Like Surface
• Caltech Press Release, 7/29/2005 "Planetary Scientists Discover Tenth Planet".
• Jet Propulsion Laboratory News Release
• NASA – Press release on discovery of tenth planet
• Press release on the Spitzer Space Telescope trying to image 2003 UB₃₁₃ again
• Press release of redefined size from Max Planck Institute for Radio Astronomy.

News stories

Wikinews has news related to:

Bigger than Pluto, possible 10th planet found

• 'Tenth Planet' found to be a whopper - Nature (registration required)
• Tenth planet discovered in outer solar system - NewScientistSpace.com
• Astronomers Discover "10th Planet" - Sky & Telescope article
• Tenth Planet Discovered - Astronomy Magazine article
• LARGER THAN PLUTO! 10th Planet Discovered? - Planetary Society
• Tenth planet found! - spaceflightnow.com
• Object Bigger than Pluto Discovered, Called 10th Planet - space.com
• Astronomers detect '10th planet' - BBC News
• You Call That a Planet? How astronomers decide whether a celestial body measures up. - Slate.com
• Sky and Telescope article on the moon of 2003 UB₃₁₃ and the diameter estimate
• Keck Observatory – Gabrielle: a moon of Xena (2003 UB₃₁₃)
• VOA News - Scientists Find '10th Planet' Bigger Than Pluto)
• Downsizing the "Tenth Planet" -- Irion 2006 (127): 1 -- ScienceNOW
• Amateur astronomers make first sighting of '10th planet' through McDonald Observatory telescope
• Hubblesite:Revised diameter (April 2006)
• 10th Planet Slightly Larger than Pluto-Yahoo! News (April 11, 2006)
• A Dwarf Planet Is Named: Eris - New York Times

The Solar System  v·d·e
Star: The Sun
Planets: Mercury - Venus - Earth - Mars - Jupiter - Saturn - Uranus - Neptune
Dwarf Planets: Ceres - Pluto - Eris
Small Bodies: Asteroids - Centaurs - TNOs - Comets - Meteoroids
Populations: Asteroid belt - Kuiper belt - Scattered disc - Oort cloud - Natural satellites
See also astronomical objects and the solar system's list of objects, sorted by radius or mass.

… | Previous minor planet | 136199 Eris | Next minor planet | … Image File history File links Wikinews-logo. ... Wikinews is a free-content news source and a project of the Wikimedia Foundation. ... Sky & Telescope is a monthly magazine providing articles and information on all aspects of astronomy, space exploration, telescope equipment, and amateur telescope making and use. ... April 11 is the 101st day of the year in the Gregorian calendar (102nd in leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... The New York Times is an internationally known daily newspaper published in New York City and distributed in the United States and many other nations worldwide. ... 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 rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... 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. ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... Media:Example. ... (28978) Ixion (ik·sye·un) is a Kuiper belt object discovered on May 22, 2001 with a diameter of < 822 km and a semimajor axis of about 39. ... The correct title of this article is (55637) 2002 UX25. ... 20000 Varuna (VAR oo na) is a Kuiper Belt object about 1060 km in diameter, estimated from a combination of thermal and optical measurements. ... (55636) 2002 TX300 (Also written as (55636) 2002 TX300) is a large Trans-Neptunian object discovered in October 15, 2002 by the NEAT program. ... (136108) 2003 EL61 (also written (136108) 2003 EL61), is a large (roughly one-third the mass of Pluto) and very unusual Kuiper belt object discovered by Mike Brown at Caltech in the United States. ... Artists impression by G. Bacon of STScI / NASA 50000 Quaoar (pronounced kwah·war, kwah·wor, or kwow·ur, Tongva ) [1] is a Trans-Neptunian object orbiting the Sun in the Edgeworth-Kuiper belt. ... (136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object discovered on March 31, 2005 by the team led by Michael Brown. ... (55565) 2002 AW197 is a trans-Neptunian object. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... (84522) 2002TC302 is a large Scattered Disk Object (SDO), orbiting the sun at a distance of 39. ... 2004 XR190 (also written 2004 XR190) is a newly discovered trans-Neptunian object located in the scattered disc. ... 90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. ... Triton (trye-tÉ™n, IPA , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ... See also Lists of astronomical objects Category: ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... 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... This is a list of solar system objects by radius, in decreasing order. ... 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 ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... Image File history File links Eight_Planets. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... The Sun is the name given to the star of our solar system. ... Our solar system: the Sun, the eight planets and the three dwarf planets. ... Note: This article contains special characters. ... Adjective Venusian or (rarely) Cytherean (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... Earth (often referred to as the Earth, or the earth) whose Latin name is Tellus (often incorrectly referred to as Terra, meaning soil) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Note: This article contains special characters. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Adjective Saturnian Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Adjective Uranian Atmospheric characteristics Atmospheric pressure 120 kPa (at the cloud level) Hydrogen 83% Helium 15% Methane 1. ... Adjective Neptunian Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... Artists impression of Pluto (background) and its satellite Charon (foreground). ... 1 Ceres (seer-eez (key), IPA , Latin CerÄ“s) was the first asteroid to be discovered (indicated by the 1 in its name). ... Adjective Plutonian Atmospheric characteristics Atmospheric pressure 0. ... A small solar system body is a term defined in 2006 by the International Astronomical Union to describe solar system objects which are not planets or dwarf planets: [1] Therefore it refers to these objects that can be further classified based on their orbit or composition: all known minor planets... An asteroid is a predominantly rocky body that orbits around its star. ... 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. ... Comet Hale-Bopp For other uses, see Comet (disambiguation). ... Look up meteoroid in Wiktionary, the free dictionary. ... Image of the main asteroid belt between the orbits of Mars and Jupiter. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... The scattered disc (or scattered disk) is a distant region of our solar system, thinly populated by icy planetoids known as scattered disk objects (SDOs), a subset of the broader family of trans-Neptunian objects (TNOs). ... This image is an artists rendering of the Oort cloud and the Kuiper Belt. ... Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ... See also Lists of astronomical objects Category: ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt, the dwarf planet Pluto, and a comet. ... 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... This is a list of solar system objects by radius, in decreasing order. ... This is a list of Solar system objects by mass, in decreasing order. ...