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90482 Orcus ( , , originally known by the provisional designation 2004 DW) is a Kuiper Belt
Kuiper belt

The Kuiper belt , sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 55 Astronomical unit from the Sun....
 object (KBO) and a likely dwarf planet
Dwarf planet

A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not Clearing the neighbourhood of planetesimals and is not a natural satellite....
 that was discovered by Michael Brown
Michael E. Brown

Michael E. Brown has been a professor of planetary astronomy at the California Institute of Technology since 2003. He was previously an associate professor at Caltech from 2002-2003 and an assistant professor at Caltech from 1997?2002....
 of Caltech
California Institute of Technology

The California Institute of Technology is a private university research university located in Pasadena, California, United States. Caltech maintains a strong emphasis on the natural sciences and engineering....
, Chad Trujillo
Chad Trujillo

Chadwick A. "Chad" Trujillo , is an astronomer and the co-discoverer of the dwarf planet Eris .Trujillo works with computer software and has examined the orbits of the numerous trans-Neptunian objects , which is the outer area of the solar system that he specialized in....
 of the Gemini Observatory
Gemini Observatory

The Gemini Observatory is an astronomical observatory consisting of two telescopes at different sites. The Northern Operations Center is located in Hilo, Hawaii, and the Southern Operations Center is in La Serena, Chile....
, and David Rabinowitz
David L. Rabinowitz

David Lincoln Rabinowitz is a researcher at Yale University. He has built Charge-coupled device cameras and software for the detection of near-Earth asteroids and Kuiper Belt Objects, and his research has helped reduce the assumed number of near-Earth asteroids by half, from 1,000-2,000 to 500-1,000 He has also assisted in the detection of...
 of Yale University
Yale University

Yale University is a private university in New Haven, Connecticut. Founded in 1701 as the Collegiate School, Yale is the Colonial Colleges institution of higher education in the United States and is a member of the Ivy League....
. The discovery images of this object were acquired on February 17, 2004. Precovery
Precovery

Precovery is a term used in astronomy that describes the process of finding the of an object in old archived images or photographic plates, for the purpose of calculating a more accurate orbit....
 images as early as November 8, 1951 were later identified.

s is a large plutino
Plutino

In astronomy, a plutino is a trans-Neptunian object in 2:3 orbital resonance with Neptune . For every 2 orbits that a Plutino makes, Neptune orbits 3 times....
 (an object in 2:3 orbital resonance
Orbital resonance

In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers....
 with Neptune
NEPTUNE

=Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
).






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90482 Orcus ( , , originally known by the provisional designation 2004 DW) is a Kuiper Belt
Kuiper belt

The Kuiper belt , sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 55 Astronomical unit from the Sun....
 object (KBO) and a likely dwarf planet
Dwarf planet

A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not Clearing the neighbourhood of planetesimals and is not a natural satellite....
 that was discovered by Michael Brown
Michael E. Brown

Michael E. Brown has been a professor of planetary astronomy at the California Institute of Technology since 2003. He was previously an associate professor at Caltech from 2002-2003 and an assistant professor at Caltech from 1997?2002....
 of Caltech
California Institute of Technology

The California Institute of Technology is a private university research university located in Pasadena, California, United States. Caltech maintains a strong emphasis on the natural sciences and engineering....
, Chad Trujillo
Chad Trujillo

Chadwick A. "Chad" Trujillo , is an astronomer and the co-discoverer of the dwarf planet Eris .Trujillo works with computer software and has examined the orbits of the numerous trans-Neptunian objects , which is the outer area of the solar system that he specialized in....
 of the Gemini Observatory
Gemini Observatory

The Gemini Observatory is an astronomical observatory consisting of two telescopes at different sites. The Northern Operations Center is located in Hilo, Hawaii, and the Southern Operations Center is in La Serena, Chile....
, and David Rabinowitz
David L. Rabinowitz

David Lincoln Rabinowitz is a researcher at Yale University. He has built Charge-coupled device cameras and software for the detection of near-Earth asteroids and Kuiper Belt Objects, and his research has helped reduce the assumed number of near-Earth asteroids by half, from 1,000-2,000 to 500-1,000 He has also assisted in the detection of...
 of Yale University
Yale University

Yale University is a private university in New Haven, Connecticut. Founded in 1701 as the Collegiate School, Yale is the Colonial Colleges institution of higher education in the United States and is a member of the Ivy League....
. The discovery images of this object were acquired on February 17, 2004. Precovery
Precovery

Precovery is a term used in astronomy that describes the process of finding the of an object in old archived images or photographic plates, for the purpose of calculating a more accurate orbit....
 images as early as November 8, 1951 were later identified.

Orbit

Thekuiperbelt Orbits Orcus2
Orcus is a large plutino
Plutino

In astronomy, a plutino is a trans-Neptunian object in 2:3 orbital resonance with Neptune . For every 2 orbits that a Plutino makes, Neptune orbits 3 times....
 (an object in 2:3 orbital resonance
Orbital resonance

In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers....
 with Neptune
NEPTUNE

=Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
). Orcus's 247 year orbit is shaped similarly to Pluto
Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
's (both have perihelia above the ecliptic
Ecliptic

The ecliptic is the apparent path that the Sun traces out in the sky during the year. As it appears to move in the sky in relation to the stars, the apparent path aligns with the planets throughout the course of the year....
), but is differently oriented. Although at one point its orbit approaches that of Neptune
NEPTUNE

=Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
, the resonance between the two bodies means that Orcus itself is always a great distance away from Neptune (there is always an angular separation of over 60 degrees between them). Over the next 14,000 years Orcus will stay more than 18 AU from Neptune.


Physical characteristics


Size and magnitude


Image:EightTNOs.png|thumb|250px|left|Orcus compared to Eris, Pluto, Makemake, Haumea, Sedna, Varuna, Quaoar, and Earth.
  1. Earth
rect 646 1714 2142 1994 The Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
  1. Eris and Dysnomia
circle 226 412 16 Dysnomia
Dysnomia (moon)

'Dysnomia' , officially ' Eris I Dysnomia', is the only known natural satellite of the dwarf planet Eris . It was discovered in 2005 by Michael E....
 circle 350 626 197 (136199) Eris
Eris (dwarf planet)

'Eris' , Minor planet names '136199 Eris', is the largest known dwarf planet in the Solar System and the ninth-largest body known to orbit the Sun directly....
  1. Pluto and Charon
circle 1252 684 86 Charon
Charon (moon)

'Charon' , discovered in 1978, is the largest moon of the dwarf planet Pluto. Following the 2005 discovery of two other natural satellites of Pluto , Charon may also referred to as 'Pluto I'....
 circle 1038 632 188 (134340) Pluto
Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
  1. Makemake
circle 1786 614 142 (136472) Makemake
  1. Haumea
circle 2438 616 155 (136108) Haumea
  1. Sedna
circle 342 1305 137 (90377) Sedna
90377 Sedna

90377 Sedna is a trans-Neptunian object and a likely dwarf planet, discovered by Michael E. Brown , Chad Trujillo and David L. Rabinowitz on November 14, 2003....
  1. Orcus
circle 1088 1305 114 (90482) Orcus
90482 Orcus

90482 Orcus is a Kuiper Belt object and a likely dwarf planet that was discovered by Michael E. Brown of California Institute of Technology, Chad Trujillo of the Gemini Observatory, and David L....
  1. Quaoar
circle 1784 1305 97 (50000) Quaoar
50000 Quaoar

50000 Quaoar is a Trans-Neptunian object and potential dwarf planet orbiting the Sun in the Kuiper belt. It was discovered on June 4, 2002 by astronomers Chad Trujillo and Michael E....
  1. Varuna
circle 2420 1305 58 (20000) Varuna
20000 Varuna

'20000 Varuna' is a large Classical Kuiper belt object Kuiper Belt object and a Plutoid candidate. It previously had the provisional designation and has been precovery in plates dating back to 1953....
  1. link to image (under all other links)
rect 0 0 2749 1994
Eighttnos
desc none
  1. - setting this to "bottom-right" will display a (rather large) icon linking to the graphic, if desired


  1. Notes:
  2. Details on the new coding for clickable images is here: mw:Extension:ImageMap
  3. While it may look strange, it's important to keep the codes for a particular system in order. The clickable coding treats the first object created in an area as the one on top.
  4. Moons should be placed on "top" so that their smaller circles won't disappear "under" their respective primaries.
The absolute magnitude
Absolute magnitude

In astronomy, absolute magnitude measures a celestial object's intrinsic brightness. To derive the absolute magnitude from the observed apparent magnitude of a celestial object its value is corrected for distance to the observer....
 of Orcus is 2.3 (comparable with the 2.6 of another KBO, 50000 Quaoar
50000 Quaoar

50000 Quaoar is a Trans-Neptunian object and potential dwarf planet orbiting the Sun in the Kuiper belt. It was discovered on June 4, 2002 by astronomers Chad Trujillo and Michael E....
). In the first quarter of 2007 a paper was published, showing the Spitzer space telescope
Spitzer Space Telescope

The Spitzer Space Telescope is an infrared space observatory. It is the fourth and final of NASA's Great Observatories program.The planned nominal mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted....
 had detected Orcus in the far infrared, during its first three years in operation, constraining the diameter to 946.3 km. Orcus
Orcus

Orcus was a Roman god of the underworld.Orcus can also refer to:* Orcus , a demon prince in the Dungeons & Dragons role-playing game...
 appears to have a high albedo
Albedo

The albedo of an object is the extent to which it diffusely reflects light from the Sun. It is therefore a more specific form of the term reflectivity....
 of ~ 20 %.

Colours and spectra

Observations in infrared
Infrared

Infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves ....
 by the European Southern Observatory
European Southern Observatory

The European Southern Observatory , is an intergovernmental research organization for astronomy, composed and supported by fourteen countries from Europe....
 give results consistent with mixtures of water ice
Water ice

Water Ice can refer to:*Ice, frozen water*A frozen dessert common in the Mid-Atlantic U.S., similar to or used as a synonym for Italian ice...
 and carbonaceous
Carbonaceous

Carbonaceous is the defining attribute of a chemical compound rich in carbon. Particularly, carbonaceous hydrocarbons are very saturation , high-molecular weight hydrocarbons, having an elevated carbon:hydrogen ratio....
 compounds. Further, the infrared spectra
Spectra

spectrum are conditions or values that vary over a continuum.Spectra may also refer to:* Sally Spectra, a fictional character on The Bold and the Beautiful...
 taken with the Gemini telescope confirmed a modest water ice signature, compatible with a cover of 15–30%, but no more than 50% of the surface. This means there is less ice than on Charon
Charon (moon)

'Charon' , discovered in 1978, is the largest moon of the dwarf planet Pluto. Following the 2005 discovery of two other natural satellites of Pluto , Charon may also referred to as 'Pluto I'....
, but a similar amount to that on Triton
Triton (moon)

'Triton' is the largest natural satellite of the planet Neptune, discovered on October 10, 1846 by William Lassell. It is the only large moon in the Solar System with a Retrograde and direct motion, which is an orbit in the opposite direction to its planet's rotation....
. Limitations were also placed on the amount of methane ice (less than 30%) leaving open the possibility for discovery of other components in the future.

KBOs display a diversity of colours and spectra even among objects with similar orbits. Orcus presents a neutral colour in comparison with the redness of an object like Ixion
28978 Ixion

'28978 Ixion' is a Kuiper belt object discovered on May 22, 2001. Ixion is a plutino and a Plutoid candidate; its estimated diameter of 800 km makes it the third largest plutino....
.

Satellite

The discovery of a satellite of Orcus was reported in IAUC 8812 on 22 February 2007. The orbit of this satellite has yet to be determined.

The satellite was found at 0.25 arcsec from Orcus with magnitude
Absolute magnitude

In astronomy, absolute magnitude measures a celestial object's intrinsic brightness. To derive the absolute magnitude from the observed apparent magnitude of a celestial object its value is corrected for distance to the observer....
 difference of 2.7. Assuming an albedo
Albedo

The albedo of an object is the extent to which it diffusely reflects light from the Sun. It is therefore a more specific form of the term reflectivity....
 similar to that of the primary, the magnitude suggests a quite substantial diameter (~220 km) compared with Orcus. The high ice content of Orcus makes Brown think its satellite is not a collisional fragment, but a small captured KBO.

S/2007 90482 Orcus1

Name

Under the guidelines of the International Astronomical Union
International Astronomical Union

The International Astronomical Union is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy....
's naming conventions
Astronomical naming conventions

In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year....
, objects with a similar size and orbit
ORBit

ORBit is a Common Object Request Broker Architecture 2.4 compliant Object Request Broker . It features mature C , C++ and Python bindings, and less developed bindings for Perl, Lisp , Pascal , Ruby , and Tcl....
 to that of Pluto
Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
 are named after underworld
Underworld

In the study of mythology and religion, the underworld is a generic term approximately equivalent to the lay term afterlife, referring to any place to which newly the dead souls go....
 deities. Accordingly, the discoverers suggested naming the object after Orcus
Orcus (mythology)

Orcus was a god of the underworld, punisher of broken oaths in Italic and Roman mythology. He was more equivalent to the Roman Pluto than to the Greek Hades, and later identified with Dis Pater....
, a god of the dead in Roman mythology
Roman mythology

Roman mythology, or more appropriately, Latin mythology, refers to the mythology beliefs of the Italic people inhabiting the region of Latium and its main city, Rome....
. The name was approved and published on November 22, 2004.

External links and sources

  • announcing the discovery but attributing it to Raymond J. Bambery, Steven H. Pravdo, Michael D. Hicks, Kenneth J. Lawrence
    Kenneth J. Lawrence

    Kenneth J. Lawrence is an American astronomer.He has discovered numerous asteroids, and also co-discovered periodic comet 152P/Helin-Lawrence. The asteroid 4969 Lawrence is named in his honor....
    , Daniel MacDonald, Eleanor F. Helin
    Eleanor F. Helin

    Eleanor Francis Helin was an American astronomer. She was principal investigator of the Near Earth Asteroid Tracking program of NASA's Jet Propulsion Laboratory....
     and Robert Thicksten / NEAT
    NEAT

    NEAT may stand for:*Near Earth Asteroid Tracking*NeuroEvolution of Augmenting Topologies*NEw Alpine Transversal *New England Actor's Theater...
  • correcting MPEC 2004-D09
  • orbital elements
  • from JPL (Java) /