- 90377 Sedna
caption= Sedna is located in the center of the green circle
title=Discovery Circumstances: Numbered Minor Planets (90001)-(95000)
publisher=IAU: Minor Planet Center
discoverer=M. Brown, C. Trujillo, D. Rabinowitz
November 14, 2003
orbit_ref =cite web
Marc W. Buie
title=Orbit Fit and Astrometric record for 90377
Deep Ecliptic Survey
September 26, 1990(JD 2 448 160.5)
semimajor=7.866 8×1013 m (525.86 AU)
perihelion=1.139 3e|13 m (76.156 AU)
aphelion=1.459e|14 m (975.56 AU)
period=around 4 404 480 d (12 059.06 a)
dimensions=1200–1600 kmcite web
title=The largest Kuiper belt objects
Michael E. Brown|work=CalTech
<1600 kmcite web
title=Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope
author=John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot
work=University of Arizona, Lowell Observatory, California Institute of Technology, NASA Ames Research Center, Southwest Research Institute, Cornell University
mass=8.3e|20–7.0e|21 kg [Radius of 590 km and density of 0.97 = 8.3e|20 kg mass. Radius of 900 km and density of 2.3 = 7.0e|21 kg mass]
sidereal_day=0.42 d (10 h) [http://cfa-www.harvard.edu/press/pr0510.html 1]
spectral_type= (red) B-V=1.24; V-R=0.78 [cite web
title=Kuiper Belt Object Magnitudes and Surface Colors
last=Tegler |first=Stephen C.
magnitude = 20.4 (Perihelic)
date=2007-11-08 last obs
title=JPL Small-Body Database Browser: 90377 Sedna (2003 VB12)
single_temperature=below 33 K
90377 Sedna (pronEng|ˈsɛdnə respell|SED|nə) is a
trans-Neptunian objectand a likely dwarf planet, discovered by Michael Brown (Caltech), Chad Trujillo( Gemini Observatory) and David Rabinowitz ( Yale University) on November 14, 2003. It is currently 88 AU from the Sun, about three times further than Neptune. For most of its orbit Sedna is farther from the Sun than any other known dwarf planet candidate. [ At present, though, Eris (dwarf planet)is further from the Sun than Sedna.]
Considered a detached object,Jewitt, David, Morbidelli, Alessandro, & Rauer, Heike. (2007). "Trans-Neptunian Objects and Comets: Saas-Fee Advanced Course 35. Swiss Society for Astrophysics and Astronomy". Berlin: Springer. ISBN 3540719571. ] Lykawka, Patryk Sofia & Mukai, Tadashi. (2007). Dynamical classification of trans-neptunian objects: Probing their origin, evolution, and interrelation. "Icarus" Volume 189, Issue 1, July , Pages 213-232. doi|10.1016/j.icarus.2007.01.001.] Sedna was discovered during a survey conducted with the
Samuel Oschin telescopeat Palomar Observatorynear 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). NASA's orbiting Spitzer Space Telescopewas also pointed toward the object, but could not detect it – putting an upper-bound on its diameterat roughly three-quarters that of Pluto.
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. Before Sedna was officially named it had provisional designationmp|2003 VB|12.
Sedna has a highly elliptical
orbit, with its aphelionestimated at 975 AU and its perihelionat about 76.16 AU. At its discovery it was approaching perihelion and about 89.6 AU from the Sun. 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 2075Lowell DES Perihelion Epoch = 2000.0 + (2479283.2278 − 2451545.0)/365.25 = 2075.9431 = (2076-1-1 - 20.7768 days) = 2075-12-11 ( [http://www.space.gs/jd.html Julian Date Converter] )] to mid 2076.cite web |url=http://home.comcast.net/~kpheider/Sedna2076.txt |title=Horizons Output for Sedna 2076/2114 |accessdate=2007-11-19 [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Sedna Horizons] ] Sedna will overtake Eris as the furthest known spheroid orbiting the Sun in 2114.
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 Telescopein March 2004 observed no such object orbiting the planetoid. New measurements from the MMT telescope suggest a much shorter rotation period, only about 10 hours, rather typical for bodies of its size. [cite journal
title=On the Rotation Period of (90377) Sedna
coauthors=Krzysztof Z. Stanek, Joel D. Hartman, Matthew J. Holman, Brian A. McLeod (CfA)
A study done by
Hal Levisonand 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 nebulaas the Sun.cite journal
journal=The Astronomical Journal
title="Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna)"
coauthors=Harold F. Levison
doi=10.1086/424617 [http://www.arxiv.org/abs/astro-ph/0403358 (Original Preprint)] ] They proposed another, less probable scenario that managed to explain Sedna's orbit very well —Sedna could have formed around a
brown dwarfabout 20 times less massive than the Sun and have been captured by the solar systemwhen the brown dwarf passed through it.
Another possible explanation, advanced by Gomes, involves perturbations of Sedna's orbit by a hypothetical planetary-sized body in the inner
Oort cloud. Recent simulations show that Sedna's orbital characteristics could be explained by perturbations by a Neptune-mass object at 2000 AU (or less), a Jupiter-mass at 5000 AU, or even an Earth-mass object at 1000 AU.cite journal
title=A distant planetary-mass solar companion may have produced distant detached objects
coauthors= John J. Matese, and Jack J. Lissauer
Another object, mpl|2000 CR|105, 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 3240 years. Its orbit may have resulted from the same processes that produced Sedna's orbit.
Sedna has an estimated diameter of between 1200 and 1600 kilometres. At the time of its discovery it was the largest object found in the
#Earthrect 646 1714 2142 1994 The Earth
#Eris and Dysnomiacircle 226 412 16 Dysnomiacircle 350 626 197 (136199) Eris
#Pluto and Charoncircle 1252 684 86 Charoncircle 1038 632 188 (134340) Pluto
#Makemakecircle 1786 614 142 (136472) Makemake
#Haumeacircle 2438 616 155 (136108) Haumea
#Sednacircle 342 1305 137 (90377) Sedna
#Orcuscircle 1088 1305 114 (90482) Orcus
#Quaoarcircle 1784 1305 97 (50000) Quaoar
#Varunacircle 2420 1305 58 (20000) Varuna
#link to image (under all other links)rect 0 0 2749 1994
# - setting this to "bottom-right" will display a (rather large) icon linking to the graphic, if desired
#Details on the new coding for clickable images is here:
#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.
#Moons should be placed on "top" so that their smaller circles won't disappear "under" their respective primaries.
solar systemsince Pluto was discovered in 1930. It is now generally believed to be the 5th largest known trans-Neptunian objectafter Eris, Pluto, dp|Makemake, and dp|Haumea.] Sedna is so far from the Sun that the temperature never rises above 33 kelvin(−240 °C; −400 °F).
Chileshow that Sedna is one of the reddest objects in the solar system, nearly as red as Mars. 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 Hawaiisuggest that Sedna's dark red color is caused by a hydrocarbonsludge, or tholin, like that found on 5145 Pholus. [cite web|url=http://www.newscientist.com/article.ns?id=dn7272
title=Distant planetoid Sedna gives up more secrets
publisher=NewScientist.com news service
accessdate=2005-03-05] 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. [cite web
title=Sedna: Mysterious Planetoid Slowly Yielding Up Its Secrets
publisher=The Planetary Society
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% methanolice with 33% methane.cite journal | author=M. A. Barucci, D. P. Cruikshank, E. Dotto, F. Merlin, F. Poulet, C. Dalle Ore, S. Fornasier and C. de Bergh| title=Is Sedna another Triton?| journal=Astronomy & Astrophysics | volume=439 | year=2005 | pages=L1–L4| doi=10.1051/0004-6361:200500144 ]
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 diskobject. Because it is a great deal closer to the Sun than was expected for an Oort cloud object, and has an inclinationroughly 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.
A number of explanations for Sedna's unusual orbit have been put forward since, including a passing star [cite journal
title="Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits"
coauthors=Benjamin C. Bromley
doi=10.1038/nature03136 ] and a distant, planet-sized object.Rodney S. Gomes, John J. Matese, and Jack J. Lissauer"A Distant Planetary-Mass Solar Companion May Have Produced Distant Detached Objects"To appear in Icarus (2006). [http://staff.on.br/rodneyg/companion/solar_companion.pdf Preprint] ]
Sedna, together with a few other objects (e.g. mpl|2000 CR|105), prompted suggestions of a new category of distant objects named "Extended scattered disc" (E-SDO), [http://www.obs-nice.fr/gladman/cr105.html "Evidence for an Extended Scattered Disk?"] ] "detached objects", D.Jewitt, A.Delsanti "The Solar System Beyond The Planets" in "Solar System Update : Topical and Timely Reviews in Solar System Sciences ", Springer-Praxis Ed., ISBN 3-540-26056-0 (2006) [http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf Preprint of the article (pdf)] ] "Distant Detached Objects" (DDO)Rodney S. Gomes, John J. Matese, and Jack J. Lissauer"A Distant Planetary-Mass Solar Companion May Have Produced Distant Detached Objects"To appear in Icarus (2006). [http://staff.on.br/rodneyg/companion/solar_companion.pdf Preprint] ] or "Scattered-Extended" in the formal classification by
Deep Ecliptic Survey.J. L. Elliot, S. D. Kern, K. B. Clancy, A. A. S. Gulbis, R. L. Millis, M. W. Buie, L. H. Wasserman, E. I. Chiang, A. B. Jordan, D. E. Trilling, and K. J. Meech"The Deep Ecliptic Survey: A Search for Kuiper Belt Objects and Centaurs. II. Dynamical Classification, the Kuiper Belt Plane, and the Core Population."The Astronomical Journal, 129 (2006), pp. [http://alpaca.as.arizona.edu/~trilling/des2.pdf preprint] .]
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
The discovery of Sedna resurrected the question of which astronomical objects should be considered
planets and which should not. On March 15, 2004, articles in the popular press reported that "the tenth planet has been discovered". This question was answered under the new International Astronomical Uniondefinition of a planet, adopted on August 24, 2006. It is unknown whether or not Sedna is in hydrostatic equilibrium. If, as currently suspected,citeweb
title=The Dwarf Planets
Michael E. Brown
publisher=California Institute of Technology, Department of Geological Sciences
accessdate=2008-02-16] it is, then it would qualify as a
dwarf planet. Sedna has a Stern–Levison parameter estimated at between 8e|−5 and 6e|−3 times that of Pluto, [Stern–Levison parameter (using unlikely highest estimated mass) = ((7e|21) / (5.9736e|24))^2 / 12,059 yr = 1.14e|−10
(Sedna 1.14e|−10) / (Pluto 1.95e|−8) = 5.8e|−3] 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.
Definition of planet
Planet X– a hypothetical planet beyond Neptune which does not match the characteristics of Sedna
protoplanetary disc– Sedna's orbit appears to imply a similar origin to the planets and asteroids.
50000 Quaoar– a planetoid beyond Pluto's orbit, discovered in 2002.
Trans-Neptunian object– an object beyond Neptune's orbit
* [http://www.gps.caltech.edu/~mbrown/papers/ps/sedna.pdf Discovery of a candidate inner Oort cloud planetoid] (Brown et.al., submitted to ApJ Letters,
16 March 2004)
*Hurt, Robert. [http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/ssc2004-05b.shtml Artist's Concept of Sedna] . California, USA: "Infrared Processing and Analysis Center".
15 March 2004.
*Hurt, Robert. [http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/ssc2004-05d.shtml Sedna's Orbit Comparisons] . California, USA: "Infrared Processing and Analysis Center".
15 March 2004.
*JPL. [http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/release.shtml Most Distant Object in Solar System Discovered] . Press release: "Jet Propulsion Laboratory".
15 March 2004.
*Whitehourse, David. [http://news.bbc.co.uk/1/hi/sci/tech/3625233.stm Sedna has no moon, say astronomers] . BBC News.
14 April 2004.
* [http://www.nasa.gov/vision/universe/solarsystem/planet_like_body.html NASA's Sedna page] (Discovery Photos)
* [http://www.gps.caltech.edu/~mbrown/sedna/ Mike Brown's Sedna page]
* [http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/release.shtml Official press release by NASA JPL/SCC]
* [http://antwrp.gsfc.nasa.gov/apod/ap040604.html Astronomy Picture of the Day 04 July 2004 – Artist's rendering of view from Sedna]
* [http://www.boulder.swri.edu/~hal/CR105.html Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects mp|2000 CR|105 and mp|2003 VB|12 (Sedna)] by Alessandro Morbidelli and Harold F. Levison
* [http://cfa-www.harvard.edu/mpec/K04/K04S73.html MPEC 2004-S73: Comment on the naming of Sedna]
* [http://www.washingtonpost.com/wp-dyn/articles/A21549-2005Feb13.html Distant Object Could Hold Secrets to Earth's Past]
* [http://seds.lpl.arizona.edu/nineplanets/nineplanets/sedna.html Sedna] on [http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html The Nine Planets Solar System Tour]
* [http://hubblesite.org/newscenter/archive/releases/2004/14/text/ Hubblesite image April 14, 2004]
* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Sedna;orb=1;view=Far Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=Sedna Ephemeris]
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