90377 Sedna

Sedna is located in the center of the green circle
Discovery
Discovered by	M. Brown, C. Trujillo, D. Rabinowitz
Discovery date	November 14, 2003
Designations
MPC designation	90377 Sedna
Alternative names	2003 VB12
Minor planet category	Trans-Neptunian object detached object
Orbital characteristics[1]
Epoch September 26, 1990 (JD 2448160. Education Brown is a Huntsville Alabama native and graduated from Virgil Grissom High School in 1983 Early career Trujillo attended Oak Park and River Forest High School in Oak Park Illinois. David Lincoln Rabinowitz (born 1960) is a researcher at Yale University. Events 1533 - Conquistadors from Spain under the leadership of Francisco Pizarro arrive in Cajamarca, Inca Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. A provisional designation in astronomy is the naming convention applied to Astronomical objects immediately following their discovery 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 scattered disc (or scattered disk) is a distant region of the Solar System that is sparsely populated by icy Minor planets known as scattered In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. Events 46 BC - Julius Caesar dedicates a Year 1990 ( MCMXC) was a Common year starting on Monday (link displays the 1990 Gregorian calendar) The Julian date (JD is the interval of time in days and fractions of a day since 4713 B 5)
Aphelion	1. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 459×1014 m (975. 56 AU)
Perihelion	1. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 1393×1013 m (76. 156 AU)
Semi-major axis	7. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 8668×1013 m (525. 86 AU)
Eccentricity	0. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 855
Orbital period	around 4,404,480 d (12,059. The orbital period is the time taken for a given object to make one complete Orbit about another object A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the 06 a)
Average orbital speed	1. In Astronomy, a Julian year (symbol a) is a unit of measurement of Time defined 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 04 km/s
Mean anomaly	357. The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units In the study of orbital dynamics the mean anomaly of an orbiting body is the Angle the body would have traveled about the center of the orbit's Auxiliary circle 457°
Inclination	11. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 934°
Longitude of ascending node	144. This article describes the unit of angle For other meanings see Degree. The longitude of the ascending node (☊ or Ω is one of the Orbital elements used to specify the Orbit of an object in space 514°
Argument of perihelion	311. The argument of periapsis (or argument of perifocus) ( ω) is the Orbital element describing the Angle of an Orbiting body's periapsis 123°
Physical characteristics
Dimensions	1,180–1,800 km[2]
Mass	8. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object 3×1020–7. 0×1021 kg[3] (0. 05–0. 42 Eris)
Mean density	2. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 0? g/cm³
Equatorial surface gravity	0. A cubic centimetre or cubic centimeter (symbol cm3 —the abbreviation cc, though widely used is deprecated is a commonly used unit of Volume The surface gravity, g, of an astronomical or other object is the Gravitational acceleration experienced at its surface 33-0. 50 m/s²
Escape velocity	0. In Physics, escape velocity is the speed where the Kinetic energy of an object is equal to the magnitude of its Gravitational potential energy 62-0. 95 km/s
Sidereal rotation period	0. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars 42 d (10 h) 1
Albedo	>0. The albedo of an object is the extent to which it diffusely reflects light from the sun 2?
Temperature	below 33 K
Spectral type	(red) B-V=1. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic 24; V-R=0. 78 [4]
Apparent magnitude	20. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 4 (Perihelic)[5]
Absolute magnitude	1. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Astronomy, absolute magnitude (also known as absolute visual magnitude) is the Apparent magnitude an object would have if it were at a standard 6

90377 Sedna (pronounced /ˈsɛdnə/ sed'-nə) is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. Education Brown is a Huntsville Alabama native and graduated from Virgil Grissom High School in 1983 The California Institute of Technology (commonly referred to as Caltech) is a private, Coeducational research university located in Pasadena Early career Trujillo attended Oak Park and River Forest High School in Oak Park Illinois. The Gemini Observatory is an astronomical observatory consisting of two 8-metre Telescopes at different sites David Lincoln Rabinowitz (born 1960) is a researcher at Yale University. Events 1533 - Conquistadors from Spain under the leadership of Francisco Pizarro arrive in Cajamarca, Inca Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. At the time of its discovery it was 89. 6 AU from the Sun and was the most distant observed natural solar system body. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the The Solar System consists of the Sun and those celestial objects bound to it by Gravity. For most of its orbit Sedna is farther from the Sun than any other known dwarf planet candidate.

Discovery

Artist's impression of 90377 Sedna. Courtesy of NASA

Sedna was discovered during a survey conducted with the Samuel Oschin telescope at Palomar Observatory near San Diego, California (USA) using Yale's 160 megapixel Palomar Quest camera and was observed within days on telescopes from Chile, Spain, and the USA (Arizona, and Hawaii). The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Samuel Oschin telescope is a 48-inch (122-m aperture Schmidt camera at the Palomar Observatory in northern San Diego County, California Palomar Observatory is a privately owned Observatory located in San Diego County California, 90 miles (145 Km) Southeast of Mount Wilson California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The United States of America —commonly referred to as the A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Chile, officially the Republic of Chile ( Spanish:) is a country in South America occupying a long and narrow Coastal strip wedged between the Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. The United States of America —commonly referred to as the The State of Arizona ( is a state located in the southwestern region of the United States. The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the NASA's orbiting Spitzer Space Telescope was also pointed toward the object, but could not detect it – putting an upper-bound on its diameter at roughly three-quarters that of Pluto. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility, SIRTF) is an Infrared Space observatory. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the

The object is named after Sedna, the Inuit goddess of the sea, who was believed to live in the cold depths of the Arctic Ocean. In Inuit mythology, Sedna ( Inuktitut Sanna, ᓴᓐᓇ is a Deity and god of the marine animals especially mammals such as seals Inuit mythology has many similarities to the Religions of other Polar regions Inuit traditional religious practices could be very briefly summarised as a The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region is the smallest and shallowest of the world's five major Before Sedna was officially named it had provisional designation 2003 VB₁₂. A provisional designation in astronomy is the naming convention applied to Astronomical objects immediately following their discovery

Orbital characteristics

Panels showing the location of Sedna in relation to other astronomical objects. Image courtesy of NASA / JPL-Caltech / R. Hurt

Sedna has a highly elliptical orbit, with its aphelion estimated at 975 AU and its perihelion at about 76. In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 16 AU. At its discovery it was approaching perihelion and about 89. 6 AU from the Sun. The Sun (Sol is the Star at the center of the Solar System. At the time of its discovery it was the most distant object in the solar system yet observed; although the orbits of some objects—like long-period comets—extend further than that of Sedna, they are basically too dim to be observed except near perihelion. Eris was later detected at 97 AU.

Sedna's precise orbital period is not yet known, but it is calculated at between 10. 5 and 12. 0 thousand years. It should reach perihelion in late 2075^[6][1] to mid 2076. ^[5] Sedna will overtake Eris as the furthest known spheroid orbiting the Sun in 2114. ^[5]

When first discovered, Sedna was believed to have an unusually long rotational period (20 to 50 days). A search was thus made for a natural satellite, the most likely cause for such a long rotation, but investigation by the Hubble Space Telescope in March 2004 observed no such object orbiting the planetoid. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into New measurements from the MMT telescope suggest a much shorter rotation period, only about 10 hours, rather typical for bodies of its size. The MMT Observatory (MMTO is an Astronomical observatory on the site of Fred Lawrence Whipple Observatory (IAU ^[7]

A study done by Hal Levison and Alessandro Morbidelli of the Observatoire de la Côte d'Azur (OCA) in Nice, France, suggested that the most likely explanation for Sedna's orbit was that it had been perturbed by a close (~800 AU) pass by another star in the first 100 million years or so of the solar system's existence, possibly one of the other stars that formed out of the same collapsing nebula as the Sun. Harold F "Hal" Levison is a Planetary scientist specializing in planetary dynamics Alessandro Morbidelli is an Italian Astronomer and Planetary scientist currently employed by the Observatoire de la Cote d'Azur in Nice. The Observatoire de la Côte d'Azur (OCA Côte d'Azur Observatory) originated in 1988 with the merger of two observatories: Observatoire Nice (nis Niçard Occitan: Niça norm or Nissa, Italian: Nizza or Nizza Marittima, Greek ^[8] They proposed another, less probable scenario that managed to explain Sedna's orbit very well —Sedna could have formed around a brown dwarf about 20 times less massive than the Sun and have been captured by the solar system when the brown dwarf passed through it. Brown dwarfs are sub- stellar objects with a mass below that necessary to maintain Hydrogen -burning Nuclear fusion reactions in their cores as do stars The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

Another possible explanation, advanced by Gomes, involves perturbations of Sedna's orbit by a hypothetical distant ‘planet’ (a planetary-sized companion in the inner Oort cloud). The Oort cloud ( ort alternatively the Öpik-Oort Cloud) is a hypothetical spherical cloud of Comets believed to lie roughly 50 000 AU, Recent simulations show that Sedna's orbital characteristics could be explained by perturbations by a Neptune-mass object at 2,000 AU (or less), a Jupiter-mass at 5,000 AU or even an Earth-mass object at 1,000 AU. ^[9]

Another object, 2000 CR₁₀₅, has an orbit similar to Sedna's but a bit less extreme: perihelion is 44. 3 AU, aphelion is 394 AU, and the orbital period is 3,240 years. Its orbit may have resulted from the same processes that produced Sedna's orbit.

Physical characteristics

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

Sedna has an estimated diameter of between 1,180 and 1,800 kilometres (730 to 1,120 miles). At the time of its discovery it was the largest object found in the solar system since Pluto was discovered in 1930. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. It is now generally believed to be the 5th largest known trans-Neptunian object after Eris, Pluto, 2005 FY₉, and 2003 EL₆₁. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. Sedna is so far from the Sun that the temperature never rises above 33 kelvin (−240 °C; −400 °F). The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724

Observations from Chile show that Sedna is one of the reddest objects in the solar system, nearly as red as Mars. Chile, officially the Republic of Chile ( Spanish:) is a country in South America occupying a long and narrow Coastal strip wedged between the Unlike Pluto and Charon, Sedna appears to have very little methane ice or water ice on its surface; Chad Trujillo and his colleagues at the Gemini Observatory in Hawaii suggest that Sedna's dark red color is caused by a hydrocarbon sludge, or tholin, like that found on 5145 Pholus. The State of Hawaii ( or həˈwaɪʔiː Hawaiian: Mokuāina o Hawaii) is a state in the United States located on an Archipelago in the In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. Tholin (after the Greek word for muddy is a Heteropolymer formed by solar Ultraviolet irradiation of simple Organic compounds such as Methane TemplateInfobox Planet. --> 5145 Pholus (ˈfoʊləs foe'-ləs from Φόλος) is a ^[10] Its surface is homogeneous in colour and spectrum; this is probably because Sedna, unlike objects nearer the sun, is rarely impacted by other bodies, which would expose bright patches like that on 8405 Asbolus. TemplateInfobox Planet. --> 8405 Asbolus (ˈæzbələs from Άσβολος) is a centaur ^[11]

Sedna's and Triton's spectra have been recently compared suggesting the following common model of the surface: 24% Triton tholin, 7% amorphous carbon, 26% methanol ice with 33% methane. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek Tholin (after the Greek word for muddy is a Heteropolymer formed by solar Ultraviolet irradiation of simple Organic compounds such as Methane See also Activated carbon Amorphous carbon is an allotrope of carbon that does not have any Crystalline structure Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. ^[12]

Classification

The discoverers have argued that Sedna is actually the first observed body belonging to the Oort cloud, saying that it is too far out to be considered a Scattered disk object. The Oort cloud ( ort alternatively the Öpik-Oort Cloud) is a hypothetical spherical cloud of Comets believed to lie roughly 50 000 AU, The scattered disc (or scattered disk) is a distant region of the Solar System that is sparsely populated by icy Minor planets known as scattered Because it is a great deal closer to the Sun than was expected for an Oort cloud object, and has an inclination roughly in line with the planets and the Kuiper belt, they described the planetoid as being an inner Oort cloud object, situated in the disc reaching from the Kuiper belt to the spherical part of the cloud. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 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 number of explanations have been put forward since, including a passing star^[8][13] and a distant, planet-sized object. ^[9]

Sedna, together with a few other objects discovered since (e. g. 2000 CR₁₀₅), prompted suggestions of a new category of distant objects named Extended scattered disc (E-SDO),^[14] detached objects,^[15] Distant Detached Objects (DDO)^[9] or Scattered-Extended in the formal classification by Deep Ecliptic Survey. ^[16]

The last classification, introduces a formal distinction between Scattered-Near objects (which could be scattered by Neptune) e. g. Eris from Scattered-Extended objects like Sedna. The distinction is made formally, using the orbital elements (see Tisserand's parameter). In Celestial Mechanics, Tisserand’s parameter (or Tisserand's invariant) is a combination of Orbital elements used in a restricted three-body problem

The discovery of Sedna resurrected the question of which astronomical objects should be considered planets and which should not. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is On March 15, 2004, articles in the popular press reported that "the tenth planet has been discovered". Events 44 BC - Julius Caesar, Dictator of the Roman Republic, is stabbed to death by Marcus Junius Brutus, "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " This question was answered under the new International Astronomical Union definition of a planet, adopted on August 24, 2006. From its beginnings denoting the "wandering stars" of the classical world the definition of " Planet " has been fraught with ambiguity Events 49 BC - Julius Caesar 's General Gaius Scribonius Curio is defeated in the Second Battle of the Bagradas River Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. It is unknown whether or not Sedna is in hydrostatic equilibrium. Hydrostatic equilibrium occurs when compression due to Gravity is balanced by a Pressure gradient which creates a Pressure gradient force in the opposite If, as currently suspected,^[17] it is, then it would qualify as a dwarf planet. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded Sedna has a Stern–Levison parameter estimated at between 8×10⁻⁵ and 6×10⁻³ times that of Pluto,^[18] and therefore cannot be considered to have cleared the neighbourhood of its orbit, even though no other objects have yet been discovered in its vicinity.

See also

• Scattered disk
• Asteroid
• Kuiper belt
• Oort cloud
• Planet
• Definition of planet
• Planet X – a hypothetical planet beyond Neptune which does not match the characteristics of Sedna
• Plutino
• protoplanetary disc – Sedna's orbit appears to imply a similar origin to the planets and asteroids. The scattered disc (or scattered disk) is a distant region of the Solar System that is sparsely populated by icy Minor planets known as scattered Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but The Kuiper belt (ˈkaɪpɚ to rhyme with "viper" sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending The Oort cloud ( ort alternatively the Öpik-Oort Cloud) is a hypothetical spherical cloud of Comets believed to lie roughly 50 000 AU, A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is From its beginnings denoting the "wandering stars" of the classical world the definition of " Planet " has been fraught with ambiguity In Astronomy, a plutino is a Trans-Neptunian object in 23 mean motion resonance with Neptune. A protoplanetary disk (or proplyd) is a rotating Circumstellar disk of dense gas surrounding a young newly formed star a T Tauri star or Herbig star
• 50000 Quaoar – a planetoid beyond Pluto's orbit, discovered in 2002.
• Trans-Neptunian object – an object beyond Neptune's orbit

References

Bibliography

• Discovery of a candidate inner Oort cloud planetoid (Brown et. al. , submitted to ApJ Letters, 16 March 2004)
• Hurt, Robert. Events 597 BC - Babylonians capture Jerusalem, replace Jehoiachin with Zedekiah as king "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Artist's Concept of Sedna. California, USA: Infrared Processing and Analysis Center. 15 March 2004. Events 44 BC - Julius Caesar, Dictator of the Roman Republic, is stabbed to death by Marcus Junius Brutus, "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "
• Hurt, Robert. Sedna's Orbit Comparisons. California, USA: Infrared Processing and Analysis Center. 15 March 2004. Events 44 BC - Julius Caesar, Dictator of the Roman Republic, is stabbed to death by Marcus Junius Brutus, "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "
• JPL. Most Distant Object in Solar System Discovered. Press release: Jet Propulsion Laboratory. 15 March 2004. Events 44 BC - Julius Caesar, Dictator of the Roman Republic, is stabbed to death by Marcus Junius Brutus, "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "
• Whitehourse, David. Sedna has no moon, say astronomers. BBC News. 14 April 2004. Events 43 BC - Battle of Forum Gallorum: Mark Antony, besieging Julius Caesar 's assassin Decimus Junius Brutus in "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "

External links

• NASA's Sedna page (Discovery Photos)
• Mike Brown's Sedna page
• Official press release by NASA JPL/SCC
• Astronomy Picture of the Day 04 July 2004 – Artist's rendering of view from Sedna
• Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR₁₀₅ and 2003 VB₁₂ (Sedna) by Alessandro Morbidelli and Harold F. Levison
• MPEC 2004-S73: Comment on the naming of Sedna
• Distant Object Could Hold Secrets to Earth's Past
• Sedna on The Nine Planets Solar System Tour
• Hubblesite image April 14, 2004
• Orbital simulation from JPL (Java) / Ephemeris