Portia (moon) 573135 220755762 2008-06-21T12:30:46Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Infobox Planet | name = Portia | image = [[Image:Uranus-Portia-Cressida-Ophelia-NASA.gif|300px]] | bgcolour = #ffc0c0 | discovery = yes | discoverer = [[Stephen P. Synnott]] / ''[[Voyager 2]]'' | discovered = [[January 3]], [[1986]] | semimajor = 66,097.265 ± 0.050 [[kilometre|km]]<ref name=Jacobson1998>{{cite journal|last=Jacobson|first=R.A.|title=The Orbits of the Inner Uranian Satellites From Hubble Space Telescope and Voyager2 Observations|journal=The Astronomical Journal|url=http://adsabs.harvard.edu/abs/1998AJ....115.1195J|year=1998|volume=115|pages=1195–1199|doi=10.1086/300263}}</ref> | eccentricity = 0.00005 ± 0.00008<ref name=Jacobson1998/> | period = 0.5131959201 ± 0.0000000093 d<ref name=Jacobson1998/> | inclination = 0.05908 ± 0.039° (to Uranus' equator)<ref name=Jacobson1998/> | satellite_of = [[Uranus (planet)|Uranus]] | physical_characteristics = yes | dimensions = 156 × 126 × 126 [[kilometre|km]]<ref name="Karkoschka2001b">{{cite journal|last=Karkoschka|first=Erich|authorlink=Erich Karkoschka|title=Voyager's Eleventh Discovery of a Satellite of Uranus and Photometry and the First Size Measurements of Nine Satellites|journal=Icarus|volume=151|pages=69–77|year=2001| doi=10.1006/icar.2001.6597|url=http://adsabs.harvard.edu/abs/2001Icar..151...69K}}</ref> | mean_radius = 70 ± 4 [[kilometre|km]]<ref name="Karkoschka2001b"/> | surface_area = ~57,000 [[square kilometre|km²]]<ref name=stub1>Calculated on the basis of other parameters</ref> | volume = ~1,300,000 [[cubic kilometre|km³]]<ref name=stub1/> | mass = ~1.7{{e|18}} [[kilogram|kg]]<ref name=stub1/> | density = ~1.3 g/cm³ (assumed) | surface_grav = ~0.023 [[Acceleration|m/s<sup>2</sup>]]<ref name=stub1/> | escape_velocity = ~0.058 km/s km/s<ref name=stub1/> | rotation = synchronous<ref name="Karkoschka2001b"/> | axial_tilt = zero<ref name="Karkoschka2001b"/> | albedo = 0.08 ± 0.01 <ref name="Karkoschka2001a">{{cite journal|last=Karkoschka|first=Erich|authorlink=Erich Karkoschka|title=Comprehensive Photometry of the Rings and 16 Satellites of Uranus with the Hubble Space Telescope|journal=Icarus|volume=151|pages=51–68|year=2001| doi=10.1006/icar.2001.6596|url=http://adsabs.harvard.edu/abs/2001Icar..151...51K}}</ref> | single_temperature = ~64 [[Kelvin|K]] }} '''Portia''' ''(por'-shə,'' {{IPAEng|ˈpɔrʃə}}) is an [[inner satellite]] of [[Uranus (planet)|Uranus]]. It was discovered from the images taken by ''[[Voyager 2]]'' on [[1986-01-03]], and was given the temporary designation '''S/1986&nbsp;U&nbsp;1'''.<ref>{{cite web|last=Smith|first=B. A.|title=IAU Circular No. 4164|date=[[January 16]] 1986|url=http://cfa-www.harvard.edu/iauc/04100/04164.html#Item1|accessdate=2006-08-06}}</ref> The moon is named after [[Portia (Merchant of Venice)|Portia]], the heroine of [[William Shakespeare]]'s play ''[[The Merchant of Venice]]''. It is also designated '''Uranus&nbsp;XII'''.<ref name="Gazetteer">{{cite web|title=Planet and Satellite Names and Discoverers|work=Gazetteer of Planetary Nomenclature|publisher=USGS Astrogeology|date=[[July 21]] 2006|url=http://planetarynames.wr.usgs.gov/append7.html|accessdate=2006-08-06}}</ref> Portia is the second-largest inner satellite of [[uranus (planet)|Uranus]] after [[puck (moon)|Puck]]. The Portian orbit, which lies inside Uranus' synchronous [[orbit]]al radius, is slowly decaying due to [[tidal deceleration]]. The moon will one day either break up into a [[planetary ring]] or hit Uranus. It heads a group of satellites called '''Portia Group''', which includes [[Bianca (moon)|Bianca]], [[Cressida (moon)|Cressida]], [[Desdemona (moon)|Desdemona]], [[Juliet (moon)|Juliet]], [[Rosalind (moon)|Rosalind]], [[Cupid (moon)|Cupid]], [[Belinda (moon)|Belinda]] and [[Perdita (moon)|Perdita]].<ref name="Karkoschka2001a"/> These satellites have similar orbits and photometric properties.<ref name="Karkoschka2001a"/> Little is known about Portia beyond its size of about 140 km,<ref name="Karkoschka2001b"/> orbit,<ref name=Jacobson1998/> and geometric [[albedo]] of about 0.08.<ref name="Karkoschka2001a"/> In the [[Voyager 2]] images, Portia appears as an elongated object whose major axis points towards [[uranus (planet)|Uranus]]. The ratio of axises of the Portia's [[prolate spheroid]] is 0.8 ± 0.1.<ref name="Karkoschka2001b"/> Its surface is grey in color.<ref name="Karkoschka2001b"/> Observations with [[Hubble Space Telescope]] and large terrestrial telescopes found water ice absorption features in the spectrum of Portia.<ref name="Karkoschka2001a"/><ref name=Dumas2003>{{cite journal|last=Dumas|first=Christophe|coaurhors=Smith, Bradford A.; and Terrile, Richard J.|title=Hubble Space Telescope NICMOS Multiband Photometry of Proteus and Puck|journal=Astronomical Journal|year=2003|volume=126|pages=1080–1085|doi=10.1086/375909|url=http://adsabs.harvard.edu/abs/2003AJ....126.1080D}}</ref> ==References== {{reflist}} ==External links== *[http://solarsystem.nasa.gov/planets/profile.cfm?Object=Ura_Portia Portia Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration] {{Uranus}} [[Category:Uranus' moons]] [[bs:Portija (mjesec)]] [[bg:Порция (спътник)]] [[cs:Portia (měsíc)]] [[cy:Portia (lloeren)]] [[da:Portia (måne)]] [[de:Portia (Mond)]] [[fr:Portia (lune)]] [[hr:Porcija]] [[it:Porzia (astronomia)]] [[ht:Pòtya]] [[la:Portia (satelles)]] [[lt:Portija (palydovas)]] [[nl:Portia (maan)]] [[ja:ポーシャ (衛星)]] [[nds:Portia (Maand)]] [[pl:Porcja (księżyc)]] [[ru:Порция (спутник)]] [[simple:Portia (moon)]] [[sk:Portia (mesiac)]] [[sl:Porcija (luna)]] [[fi:Portia]] [[sv:Portia]] [[uk:Порція (супутник)]] [[zh:天卫十二]]