(136108) 2003 EL₆₁ (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. of the Instituto de Astrofísica de Andalucía at Sierra Nevada Observatory in Spain and Mike Brown's group at Caltech in the United States. The MPC currently gives formal discovery credit to Ortiz's group, who were first to announce the object. Image File history File links 2003EL61art. ... José-Luís Ortiz Moreno is an astronomer at the Instituto de Astrofísica de Andalucía, Spain. ... Michael (Mike) E. Brown (born c. ... is the 362nd day of the year (363rd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday 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. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 230th day of the year (231st in leap years) in the Gregorian calendar. ... JD is the IATA code for Japan Airlines domestic service JD or jd may also stand for: Juris Doctor, a law degree possessed by most lawyers in the United States of America John Dorian, the fictional lead character of the sitcom Scrubs John Davidson (ice hockey) Former player for the... A diagram of Keplerian orbital elements. ... 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. ... Look up giga- in Wiktionary, the free dictionary. ... This article is about the unit of length. ... The astronomical unit (AU or au or a. ... (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. ... Look up day in Wiktionary, the free dictionary. ... 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. ... This article is about the unit of time. ... 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 science fiction novella by William Shunn, see Inclination (novella). ... This article describes the unit of angle. ... 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. ... For other uses, see Mass (disambiguation). ... “Kg” redirects here. ... For other uses, see Density (disambiguation). ... 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. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Space Shuttle Atlantis launches on mission STS-71. ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... For other uses, see Temperature (disambiguation). ... For other uses, see Kelvin (disambiguation). ... 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. ... The Kuiper belt, derived from data from the Minor Planet Center. ... For other uses, see Pluto (disambiguation). ... José-Luís Ortiz Moreno is an astronomer at the Instituto de Astrofísica de Andalucía, Spain. ... The Sierra Nevada Observatory (OSN) (37° 03′ 51″ N 03° 23′ 05″ W 2896m) is located at Loma de Dilar in the Sierra Nevada mountain range, in the province of Granada. ... Michael (Mike) E. Brown (born c. ... California Institute of Technology The California Institute of Technology (commonly known as Caltech) is a private, coeducational university located in Pasadena, California, in the United States. ...

Its two moons, rapid rotation, extreme elongation, and high albedo due to crystalline water ice on the surface, make it exceptional among the known cubewanos. It is thought to be the largest member of a collisional family, created in a single break-up event that is responsible for its other unusual characteristics. Albedo is the ratio of reflected to incident electromagnetic radiation. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ...

Name

Before the discovery of the object was published and designated, the Caltech team used the nickname "Santa", which stems from its discovery just after Christmas, on December 28, 2004, although the team had acquired images of it from May 6, 2004. Following IAU guidelines, the object should be formally named after a deity related to a creation myth. The Caltech team submitted formal names from Hawaiian mythology in September 2006 for (136108) 2003 EL₆₁ and both of its satellites "to pay homage to the place where the satellites were discovered." However, since the discoverers of a body are generally given the right to name it, and the Spanish team now has formal credit for (136108) 2003 EL₆₁ itself, while the Caltech team has credit for the moons, it is not clear if the submitted names will be accepted. For other uses, see Christmas (disambiguation). ... is the 362nd day of the year (363rd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... is the 126th day of the year (127th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... IAU redirects here. ...

Discovery controversy

(136108) 2003 EL₆₁ is circled in red

[[Pi * e]], an astronomer at the Sierra Nevada Observatory in Spain, and colleagues Francisco José Aceituno Castro and Pablo Santos-Sanz announced the discovery of the object on July 25, 2005, when they re-analysed observations they had made on March 7, 2003. They then scoured older archives (a process known as precovery) and found the object in images dating back to 1955. Ortiz's group announced their discovery on July 27, 2005, and it was published two days later by the MPC. Image File history File links 41354795_object_203. ... Image File history File links 41354795_object_203. ... The Sierra Nevada Observatory (OSN) (37° 03′ 51″ N 03° 23′ 05″ W 2896m) is located at Loma de Dilar in the Sierra Nevada mountain range, in the province of Granada. ... is the 206th day of the year (207th 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 66th day of the year (67th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Precovery is a term used in astronomy that describes the process of finding the image of an object (usually a minor planet) in old archived images or photographic plates, for the purpose of calculating a more accurate orbit. ... is the 208th day of the year (209th 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. ... The Minor Planet Center operates at the Smithsonian Astrophysical Observatory (SAO), which is part of the Center for Astrophysics (CfA) along with the Harvard College Observatory (HCO). ...

A Caltech team consisting of Michael E. Brown, Chad Trujillo, and David Rabinowitz had been observing the object for half a year with the 1.3 m SMARTS Telescope, but had not yet made the data public. Brown and his collaborators initially supported giving Ortiz and his group credit for the discovery, but withdrew support when they found reason to suspect that Ortiz may have used discovery data from Brown's team, which had inadvertently been made publicly available on the web. California Institute of Technology The California Institute of Technology (commonly known as Caltech) is a private, coeducational university located in Pasadena, California, in the United States. ... Michael (Mike) E. Brown (born c. ... Chadwick A. Chad Trujillo (born November 22, 1973), is the co-discoverer of Eris, which he claims to be the Tenth Planet. ... David L. Rabinowitz (born 1960) is a professor at Yale University researching the Kuiper belt and the outer solar system. ...

A week before Ortiz's discovery announcement, on July 20, Brown's team had published an abstract of a report they intended to use to announce the discovery, in which the object was referred to by the internal code name K40506A. Typing this code into internet search engines allowed anyone to find the observation logs of Brown's group, including the observed positions of the object. Third-party web server logs indicated that the page in question had been accessed by an IP address used by computers at the Instituto de Astrofísica de Andalucía where Ortiz's group worked.^[1] Brown's group accused Ortiz's group of a serious breach of scientific ethics and asked the Minor Planet Center to strip them of discovery status.^[2] is the 201st day of the year (202nd in leap years) in the Gregorian calendar. ... The Minor Planet Center operates at the Smithsonian Astrophysical Observatory (SAO), which is part of the Center for Astrophysics (CfA) along with the Harvard College Observatory (HCO). ...

Ortiz later admitted he accessed the internet telescope logs with the relevant information a day before making his announcement, but denied any wrongdoing.^[3] According to him they did not use the data, other than checking them out of curiosity whether it could be the same object they had found in their 2003 images that same month. This after they realized the object in the abstract by Brown et al. seemed to be an object with similar characteristics. Googling the informal designation mentioned in the abstract, they ended up at the telescope log.

The ambiguity in who discovered the object stems from the fact that the Caltech group of Brown did not submit their discovery to the Minor Planet Center for a year after detecting it in their images. Standing protocol is that the one who first does submit a report to the MPC with enough positional data for a decent orbit determination, gets discovery credit. This is what Ortiz' group did, thus following correct protocol, using their 2003 imagery, 2005 follow-up imagery, and "precovery" positions from historic archives. The Minor Planet Center operates at the Smithsonian Astrophysical Observatory (SAO), which is part of the Center for Astrophysics (CfA) along with the Harvard College Observatory (HCO). ...

The Minor Planet Center's discovery circumstances database gives the group of Ortiz et al. as the formal discoverers of the object.

On July 29, 2005, shortly after the Ortiz discovery announcement, Brown's group announced the discovery of another Kuiper belt object, Eris, which is more distant and is thought to be larger than the dwarf planet Pluto. The announcement was made earlier than planned, at the urging of the Minor Planet Center, to forestall the possibility of that discovery leaking out as well. 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. ... Absolute magnitude: −1. ... Artists impression of Pluto (background) and Charon (foreground). ... For other uses, see Pluto (disambiguation). ... The Minor Planet Center operates at the Smithsonian Astrophysical Observatory (SAO), which is part of the Center for Astrophysics (CfA) along with the Harvard College Observatory (HCO). ...

Size and composition

(136108) 2003 EL₆₁ compared to Eris, Pluto, (136472) 2005 FY₉, Sedna, Orcus, Quaoar, Varuna, and Earth.

The only method to estimate the size of a small trans-Neptunian object is its magnitude assuming a value for the albedo. For larger objects, thermal emission can provide a size directly. (136108) 2003 EL₆₁ is exceptional because its two moons provide the means to determine directly the mass of the system from Kepler's third law. The estimated mass is 4.2 × 10²¹ kg, 28% the mass of the Plutonian system.^[4] Because (136108) 2003 EL₆₁ rotates roughly once every four hours, faster than any other known body in the solar system larger than 100 km in diameter, it should be distorted into a triaxial ellipsoid. (136108) 2003 EL₆₁ displays large fluctuations in brightness. Although these fluctuations could be due to a mottled surface, it is thought that this fluctuation is due to an elongated shape. Rapid rotation and elongated shape result in constraints on the density (the denser the object, the less elongated), estimated at 2.6–3.3 g/cm³, suggesting substantial non-ice content (compare with Pluto's density of 2.0 g/cm³ and Moon's density of 3.3 g/cm³). These limits on the density, together with the known mass, give another way to constrain the dimensions of the object.^[5] (136108) 2003 EL₆₁ has approximately the diameter of Pluto along its longest dimension, and half that along its shortest. This would make it one of the largest trans-Neptunian objects discovered so far; possibly fourth after Eris, Pluto and arguably (136472) 2005 FY₉, larger than Sedna, Orcus, and Quaoar. 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. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ... A triaxial ellipsoid is an ellipsoid with all three axes having positive lengths, which cannot be neglected as insignificant. ... 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. ... For other uses, see Pluto (disambiguation). ... (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. ... 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. ... 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. ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ...

The short rotation period of (136108) 2003 EL₆₁ may have been caused by a giant impact, which also created its satellites. (136108) 2003 EL₆₁ may not be the only elongated, rapidly rotating, large object in the Kuiper Belt. In 2002, Jewitt and Sheppard suggested that Varuna should be elongate, based on its rapid rotation (see the references there). The Kuiper belt, derived from data from the Minor Planet Center. ... 20000 Varuna (VAR oo na) is a large classical Kuiper Belt object (KBO). ... 20000 Varuna (VAR oo na) is a large classical Kuiper Belt object (KBO). ...

2003 EL61, 2002 TX₃₀₀ and four smaller Kuiper belt objects are traveling in similar orbits and all have a similar color and proportion of water ice to it. Mike Brown and his team have postulated that they are the remnants of a past impact and their surfaces were once ejected from the mantle of the original object.^[6] (See Collisional family below). (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 Kuiper belt, derived from data from the Minor Planet Center. ... Mike Brown can refer to the following people: Michael E. Brown the astronomer. ...

Surface

Gemini telescope obtained spectra of (136108) 2003 EL₆₁, which show strong water ice features similar to the surface of Pluto's moon Charon. Trujillo, Brown, et al. report crystalline water ice.^[7] The Gemini Observatory is an astronomical observatory consisting of two 8-metre telescopes at different sites. ... In most modern usages of the word spectrum, there is a unifying theme of between extremes at either end. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about water ice. ... 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. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... What may be Americas most common name crossing all races. ...

Water ice has been reported on many trans-Neptunian objects but typically in the form of amorphous ice. Crystalline ice is unstable on timescales of 10 million years under conditions in the Kuiper Belt. This discovery hints at resurfacing processes producing fresh ice. As surprising as the crystalline form is the inferred amount of ice. Following the report, the surface of (136108) 2003 EL₆₁ appears to be ⅔ to ⅘ pure ice, with the remainder of the surface material of unknown composition. Everyday ice is a crystal, which means its molecules are lined up in a repeating pattern. ...

(136108) 2003 EL₆₁ has an albedo approaching that of pure snow, consistent with crystalline ice on the surface. This very high albedo does not appear to be unique among large TNOs. Recent measurements of Eris imply an even higher (inferred) albedo (0.86) for that object. Eris (IPA or ), officially designated 136199 Eris, is the largest known dwarf planet in the solar system. ...

Orbit

Orbits of 2003 EL₆₁ (yellow) and Pluto (red).

(136108) 2003 EL₆₁ is classified as a classical trans-Neptunian object with an orbit common for large cubewanos: the perihelion is close to 35 AU and significantly inclined. The diagram shows a view of its orbit in yellow, (Pluto in red, Neptune in grey) and position (as of April 2006). The object passed its aphelion (Q) in 1991, and is currently more than 50 AU from the Sun and takes 285 Earth Years for a complete orbit. Image File history File links TheKuiperBelt_Orbits_2003EL61. ... Image File history File links TheKuiperBelt_Orbits_2003EL61. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ... 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 cubewano is a Kuiper belt object, orbiting beyond Pluto and not controlled by resonances with Neptune. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... 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. ... For other uses, see Pluto (disambiguation). ... For other uses, see Neptune (disambiguation). ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

The inclination of its orbit (~28° to compare with 17° for Pluto) and its current position, far from the ecliptic where most of the early surveys took place, combined with a slow mean motion explain why (136108) 2003 EL₆₁ was only discovered recently, in spite of its magnitude. Mean Motion, , is a measure of how far a satellite has progressed around its orbit, from perigee. ...

Moons

Main article: 2003 EL61's natural satellites

Two small satellites have been discovered orbiting (136108) 2003 EL₆₁. 2003 EL61, a Kuiper Belt object, has two known moons. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ...

S/2005 (136108) 1

S/2005 (2003 EL₆₁) 1 (provisional designation; nicknamed "Rudolph" by the Caltech team), renamed S/2005 (136108) 1 once its primary was numbered, was the first satellite discovered around (136108) 2003 EL₆₁. It orbits once every 49.12 ± 0.03 days with semimajor axis 49,500 ± 400 km and eccentricity 0.050 ± 0.003[1]. Mutual occultations of the moon and the primary, as seen from Earth, occurred in 1999 and will not occur again until 2138. Image File history File links Merge-arrow. ... 2003 EL61, a Kuiper Belt object, has two known moons. ... 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... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... In Islam the occulation is the name given to the disappearance of the Twelfth Imam. ... (Redirected from 2138) (21st century - 22nd century - 23rd century - other centuries) The twenty-second century comprises the years 2101 to 2200. ...

Only the total mass of the system is known, but assuming the moon has the same density and albedo as the primary, the mass of the satellite is 1% of the mass of (136108) 2003 EL₆₁ and it has a diameter of ~310 km.^[8] For other uses, see Satellite (disambiguation). ...

Strong absorption features at 1.5 and 2 micrometres discovered in the infrared spectrum are consistent with absorption due to water ice. Their depth suggests that much of the satellite’s surface is covered with ice.^[9] A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... For other uses, see Infrared (disambiguation). ...

S/2005 (136108) 2

S/2005 (2003 EL₆₁) 2 (provisional designation), later renamed S/2005 (136108) 2, is the smaller inner satellite of (136108) 2003 EL₆₁. The object has been nicknamed "Blitzen".^[10] Image File history File links Merge-arrow. ... 2003 EL61, a Kuiper Belt object, has two known moons. ... 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...

Its discovery was announced on November 29, 2005. It was found 39,300 km away and, with the assumption of a circular orbit, it orbits the primary in 34.7 ± 0.1 days, and is inclined 39 ± 6° from the larger moon. is the 333rd day of the year (334th 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. ...

The measured brightness implies a diameter 12% that of (136108) 2003 EL₆₁, ~170 km, assuming similar albedo.

Collisional family

The collisional family of 2003 EL₆₁ (in green), other classical KBO (blue), Plutinos and other resonant objects (red) and SDO (grey). Radius is semi-major axis, angle orbital inclination.

EL61 is the largest member of a collisional family, similar to asteroid families: a group of objects with similar orbital parameters and common physical characteristics, presumably with a common origin in a disruptive impact of the progenitor object of EL61.^[11] Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... In astronomy, a resonant Trans-Neptunian Object is a Trans-Neptunian Object (TNO) in mean motion orbital resonance with Neptune. ... 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). ... Minor planet is the official term for asteroids and trans-Neptunian objects. ...

The family, the first to be identified among TNOs, includes EL61 and its moons, 2002 TX₃₀₀, (24835) 1995 SM₅₅, (19308) 1996 TO₆₆, (120178) 2003 OP₃₂ and (145453) 2005 RR₄₃. The dispersion of the proper orbital elements of the members is a few percent or less (5% for semi-major axis, 1.4° for the inclination and 0.08 for the eccentricity). The diagram illustrates the orbital elements of the members of the family in relation to other TNOs. (55636) 2002 TX300 (Also written as (55636) 2002 TX300) is a large Trans-Neptunian object discovered in October 15, 2002 by the NEAT program. ... (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. ... (120178) 2003 OP32, also written as (120178) 2003 OP32,is a trans-Neptunian object (TNO) that resides in the Kuiper belt. ... (145453) 2005 RR43, also written as (145453) 2005 RR43, is a trans-Neptunian object (TNO). ... The proper orbital elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. ... 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. ... 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. ...

The objects' common physical characteristics include neutral colours and deep infrared absorption features (at 1.5 and 2.0 μm) typical of water ice.^[12] A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ...

Collisional formation of the family requires a progenitor some 1660 km in diameter, with a density of ~2.0 g/cm³, similar to Pluto and Eris. During the formational collision, EL61 lost roughly 20% of its mass, mostly ice, and became denser.^[11] For other uses, see Pluto (disambiguation). ... Absolute magnitude: −1. ...

The current orbits of the members of the family cannot be accounted for by the formational collision alone. To explain the spread of the orbital elements, an initial velocity dispersion of ~400 m/s is required, but such a velocity spread should have dispersed the fragments much further. This problem applies only to 2003 EL₆₁ itself; the orbital elements of all the other objects in the family require an initial velocity dispersion of ~140 m/s. To explain this mis-match in the required velocity dispersion, Brown et al. suggest that 2003 EL₆₁ initially had orbital elements closer to those of the other members of the family and its orbit (especially the orbital eccentricity), changed after the collision. Unlike the other members of the family, EL61 is in a chaotic orbit, near the 7:12 resonance with Neptune, which would increase EL61's eccentricity to its current value.^[11] In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ...

References

is the 256th day of the year (257th 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. ... 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. ... is the 264th day of the year (265th 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. ... 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. ... Michael (Mike) E. Brown (born c. ... This article or section does not cite its references or sources. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... This article or section does not cite its references or sources. ... Michael (Mike) E. Brown (born c. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... 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 74th day of the year (75th in leap years) in the Gregorian calendar. ... Chadwick A. Trujillo (born November 22, 1973) is a postdoctoral scholar at Caltech researching the Edgeworth-Kuiper belt and the outer solar system. ... What may be Americas most common name crossing all races. ... David L. Rabinowitz (born 1960) is a professor at Yale University researching the Kuiper belt and the outer solar system. ... Michael (Mike) E. Brown (born c. ... 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. ... Michael (Mike) E. Brown (born c. ...

External links

• NASA visualization of the orbit
• Updated data
• MPEC listing for 2003 EL₆₁
• Space.com story: Large new world discovered beyond Neptune
• New Scientist story: New world found in outer solar system
• BBC story: Distant object found orbiting Sun
• Astronomers Discover "10th Planet" - Sky & Telescope article describing the discovery of (136108) 2003 EL₆₁ and 136199 Eris.
• Michael Brown's webpage
• New Scientist story: Distant solar system body may be cigar-shaped
• BBC story: Record spin rate for cosmic body
• news @ nature.com story: Cosmic 'cigar' spins at astonishing pace; Pluto's neighbour has a very unexpected shape, 9 September 2005.
• New York Times story: "One find, two astronomers", September 13, 2005.
• S.C. Tegler, W. Grundy, W. Romanishin, G. Consolmagno, K. Mogren, F. Vilas: Optical Spectroscopy of the Large Kuiper Belt Objects 136472 (2005 FY9) and 136108 (2003 EL61). Preprint