20000 Varuna ("VAR oo na") is a large classical Kuiper Belt object (KBO). It previously had the provisional designation 2000 WR₁₀₆ and has been precovered in plates dating back to 1953. Under the International Astronomical Union's 2006 draft proposal for the definition of a planet, Varuna would be labelled a dwarf planet if it were proven to be spherical. Image File history File links No higher resolution available. ... Robert S. McMillan is an astronomer at the University of Arizona, and heads the Spacewatch project, which studies minor planets. ... Spacewatch is a project at the University of Arizona that specializes in the study of minor planets, and including various types of asteroids and comets. ... November 28 is the 332nd day (333rd in leap years) of the year in the Gregorian calendar. ... 2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. ... m. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... July 14 is the 195th day (196th in leap years) of the year in the Gregorian calendar, with 170 days remaining. ... shelby was here 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... 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. ... The or meter (see spelling differences) is a measure 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. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... 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. ... 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. ... 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 (☊, 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... km redirects here. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... BIC pen cap, about 1 gram. ... 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. ... The hour (symbol: h) is a unit of time. ... Albedo is the ratio of reflected to incident electromagnetic radiation power. ... Fig. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... 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. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... 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... 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. ... Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... 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 Charon (foreground). ... For other uses, see sphere (disambiguation). ...

Name

Varuna is named after the Hindu god Varuna. He is the god of the sky, rain, oceans and rivers, and the celestial ocean. He is also a god of law and the underworld, especially concerned with the souls of the drowned. He is sometimes considered analogous to Poseidon. // In Hinduism In Hindu mythology, the Asura (Sanskrit: असुर) are a group of power-seeking deities, sometimes misleadingly referred to as demons. ... In Vedic religion, Varuna (Devanagari:वरुण, IAST:) is a god of the sky, of rain and of the celestial ocean, as well as a god of law and of the underworld. ... A typical daytime sky. ... Rain is a source of precipitation which forms when separate drops of water fall to the Earths surface from clouds. ... Ocean (Okeanos, a Greek god of sea and water; Greek ωκεανός) covers almost three quarters (71%) of the surface of the Earth. ... For the Second World War frigate class, see River class frigate The Murray River in Australia A waterfall on the Ova da Fedoz, Switzerland A river is a large natural waterway. ... Several mythologies have the notion of a celestial ocean or river, enveloping the world both above the heavenly sphere and below the underworld. ... Lady Justice or Justitia is a personification of the moral force that underlies the legal system (particularly in Western art). ... // 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 dead souls go. ... Neptune reigns in the city of Bristol. ...

Size

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

The size of the large KBOs can be determined by simultaneous observations of thermal emission and reflected sunlight. Unfortunately, thermal measures, intrinsically weak for distant objects are further hampered by the absorption of the Earth atmosphere as only the weak ‘tail’ of the emissions is accessible to Earth-based observations. In addition, the estimates are model-dependent with the unknown parameters (e.g. pole orientation and thermal inertia) to be assumed. Consequently, the estimates of the albedo vary resulting in sometimes substantial differences in the inferred size. 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. ...

A recent thermal model estimates the size at 936 ⁺²³⁸₋₃₂₄ km.^[4] This estimate is based on earlier results (900 ⁺¹²⁹₋₁₄₅) ^[5] and (1060 ⁺¹⁸⁰_−-220).^[6]

Orbit

Orbits of Varuna (blue) and Pluto (red).

Varuna is classified as a classical trans-Neptunian object and follows a near-circular orbit with a semi-major axis of ~43 AU, similar to that of Quaoar but more inclined. Its orbital period is simmilar to Quaoar at 283 Earth years. The graph shows the polar view (top; Varuna’s orbit in blue, Pluto’s in red, Neptune in grey). The spheres illustrate the current (April 2006) positions, relative sizes and colours. The perihelia (q), aphelia (Q) and the dates of passage are also marked. Interestingly, the orbits of Varuna and Pluto have similar inclination and are similarly oriented (the nodes of both orbits are quite close). 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. ... 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 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. ... The astronomical unit (AU or au or a. ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... 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. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... 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. ... An orbital node is one of the two points where an inclined orbit crosses a plane of reference (e. ...

At 43 AU and on a near-circular orbit, unlike Pluto which is in 2:3 orbital resonance with Neptune, Varuna is free from any significant perturbation from Neptune. The ecliptic view illustrates the comparison of Varuna's near-circular orbit with that of Pluto (highly eccentric, e=0.25), both similarly inclined.
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ...

Physical characteristics

Varuna has a rotational period of approximately 3.17 hours (or 6.34 hours, depending on whether the light curve is single or double-peaked). Given the rapid rotation, rare for objects so large, Varuna is thought to be an elongated spheroid (ratio of axis 2:3), with a mean density around 1g/cm³ (roughly the density of water ice).^[7] Examination of Varuna's light curve has found that the best-fit model for Varuna is a triaxial ellipsoid with the axes a,b,c in relations: b/a = 0.63 − 0.80, c/a = 0.45 − 0.52 and a bulk density of 0.992 g/cm³.^[2] Since the discovery of Varuna, another, even larger, rapidly rotating (3.9 h) object (136108) 2003 EL₆₁ has been discovered, also thought to have an elongated shape.^[8] In astronomy, a light curve is a graph of light intensity as a function of time. ... In astronomy, a light curve is a graph of light intensity as a function of time. ... 3D rendering of an ellipsoid In mathematics, an ellipsoid is a type of quadric that is a higher dimensional analogue of an ellipse. ... BIC pen cap, about 1 gram. ... 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. ... (also written (136108) 2003 EL61), nicknamed Santa, is a large Kuiper belt object, roughly one-third the mass of Pluto, discovered by Mike Browns group at Caltech in the United States and J. L. Ortiz et al. ...

The surface of Varuna is moderately red (similar to Quaoar) but exceptionally dark (albedo<0.04) compared with other large classical Kuiper Belt objects, suggesting that the surface is largely devoid of ice. 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... A cubewano is any substantial Kuiper belt object, orbiting beyond about 41 AU and not controlled by resonances with the outer planets. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ...

References

1. ^ Stansberry (2005). TNO/Centaur diameters and albedos. Retrieved on 2006-11-08.
2. ^ ^{a b} Lightcurves Lacerda P., Jewitt D. Dentisities Of Solar System Objects From Their Rotational Lightcurves", accepted to AJ Dec. 2006 Preprint
3. ^ TNO and Centaur Colors. Retrieved on 2006-11-08.
4. ^ Grundy, W. M.; Noll, K. S.; Stephens, D. C. (2005). "Diverse albedos of small trans-neptunian objects". Icarus, 176: 184-191.  Preprint on arXiv.
5. ^ Jewitt D, Aussel H, Evans A (2001). "The size and albedo of the Kuiper-belt object (20000) Varuna". Nature 411 (6836): 446-7.  PMID 11373669. Reprint on the Author's site.
6. ^ E. Lellouch, R. Moreno, J. L. Ortiz, G. Paubert, A. Doressoundiram and N. Peixinho (2002). "Coordinated thermal and optical observations of Trans-Neptunian object (20 000)Varuna from Sierra Nevada". Astronomy & Astrophysics 391: 1133-1139.  Preprint on arXiv.
7. ^ Jewitt D, Sheppard S (2002). "Physical Properties Of Trans-Neptunian Object (20000) Varuna". Astronomical Journal 123 (April): 2110–2120.  Preprint on arXiv.
8. ^ D. L. Rabinowitz, K. M. Barkume, M. E. Brown, H. G. Roe, M. Schwartz, S. W. Tourtellotte, C. A. Trujillo (2005), Photometric Observations Constraining the Size, Shape, and Albedo of 2003 EL₆₁, a Rapidly Rotating, Pluto-Sized Object in the Kuiper Belt, The Astrophysical Journal (2006), 639, Issue 2, pp. 1238-1251 Preprint on arXiv (pdf)

For the Manfred Mann album, see 2006 (album). ... November 8 is the 312th day of the year (313th in leap years) in the Gregorian calendar, with 53 days remaining. ... For the Manfred Mann album, see 2006 (album). ... November 8 is the 312th day of the year (313th in leap years) in the Gregorian calendar, with 53 days remaining. ... Nature is one of the most prominent scientific journals, first published on 4 November 1869. ... The Astronomical Journal is a monthly scientific journal published by the University of Chicago Press on behalf of the American Astronomical Society. ... 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. ...

External links

• Size and Albedo of Kuiper Belt Object (20000) Varuna. David Jewitt's Home Page. Retrieved on 2005-08-15. Site updated Reretrived on 2006-07-10
• Orbit simulation from NASA JPL site