View source for Ophiuchus

{{Short description|Constellation straddling the celestial equator}}
{{Other uses}}
{{Sky|17|00|00|+|00|00|00|10}}
{{Use dmy dates|date=September 2021}}
{{Infobox constellation
| name = Ophiuchus
| abbreviation = Oph
| genitive = Ophiuchi
| pronounce = {{IPAc-en|ˌ|ɒ|f|i|ˈ|juː|k|ə|s}}<br/>genitive: {{IPAc-en|ˌ|ɒ|f|i|ˈ|juː|k|aɪ}}
| symbolism = the serpent-bearer
| RA = {{RA|17}}
| dec= {{DEC|−8}}
| family = [[Hercules Family|Hercules]]
| quadrant = SQ3
| areatotal = 948
| arearank = 11th
| numbermainstars = 10
| numberbfstars = 65
|ophicues = 15
| numberbrightstars = 5
| numbernearbystars = 11
| brighteststarname = [[Alpha Ophiuchi|α Oph]] (Rasalhague)
| starmagnitude = 2.08
| neareststarname = [[Barnard's Star]]
| stardistancely = 5.98
| stardistancepc = 1.83
| numbermessierobjects = 7
| meteorshowers = {{ubl|[[Ophiuchids]]|Northern [[May Ophiuchids]]|Southern May Ophiuchids|[[Theta Ophiuchids]]}}
| bordering = {{ubl|[[Hercules (constellation)|Hercules]]|[[Serpens|Serpens Cauda]]|[[Serpens|Serpens Caput]]|[[Libra (constellation)|Libra]]|[[Scorpius]]|[[Sagittarius (constellation)|Sagittarius]]|[[Aquila (constellation)|Aquila]]}}
| latmax = [[80th parallel north|80]]
| latmin = [[80th parallel south|80]]
| month = July
}}

'''Ophiuchus''' ({{IPAc-en|ˌ|ɒ|f|i|ˈ|juː|k|ə|s}}) is a large [[constellation]] straddling the [[celestial equator]]. Its name comes from the [[Ancient Greek]] {{wikt-lang|grc|ὀφιοῦχος}} ({{grc-transl|ὀφιοῦχος}}), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation [[Serpens]]. Ophiuchus was one of the 48&nbsp;constellations listed by the 2nd-century astronomer [[Ptolemy]], and it remains one of the 88&nbsp;modern constellations. An old alternative name for the constellation was '''Serpentarius'''.<ref>{{cite web |title=Star Tales – Ophiuchus |url=http://www.ianridpath.com/startales/ophiuchus.html |access-date=2021-06-25}}</ref>

==Location==
[[File:Guisard - Milky Way.jpg|thumbnail|left|upright=1.2|[[Rho Ophiuchi]], shown with a surrounding bluish cloud slightly above a pentagon of stars in Scorpius, with the main band of the Milky Way much further to the left]]
Ophiuchus lies between [[Aquila (constellation)|Aquila]], [[Serpens]], [[Scorpius]], [[Sagittarius (constellation)|Sagittarius]], and [[Hercules (constellation)|Hercules]], northwest of the center of the [[Milky Way]]. The southern part lies between [[Scorpius]] to the west and [[Sagittarius (constellation)|Sagittarius]] to the east.<ref>{{Cite book |title=Nightwatch A practical Guide to Viewing the Universe Revised Fourth Edition: Updated for use Through 2025 |last=Dickinson |first=Terence |publisher=Firefly Books |isbn=1-55407-147-X |location=US |pages=185 |year=2006}}</ref> In the [[northern hemisphere]], it is best visible in summer.<ref>{{Cite book |title=Nightwatch A Practical Guide to Viewing the Universe Revised Fourth Edition: Updated for Use Through 2025 |last=Dickinson |first=Terence |publisher=Firefly Books|isbn=1-55407-147-X |location=US |pages=44–59 |year=2006}}</ref> It is opposite of [[Orion (constellation)|Orion]]. Ophiuchus is depicted as a man grasping a [[Serpens|serpent]]; the interposition of his body divides the snake constellation Serpens into two parts, [[Serpens Caput]] and [[Serpens Cauda]]. Ophiuchus straddles the equator with the majority of its [[solid angle|area]] lying in the southern hemisphere. [[Rasalhague]], its brightest star, lies near the northern edge of Ophiuchus at about {{dec|+12|30}} declination.<ref>{{Cite web |url=https://in-the-sky.org/data/object.php?id=TYC1000-2508-1 |title=Rasalhague (Star) |last=Ford |first=Dominic |website=in-the-sky.org |language=en |access-date=2018-06-23}}</ref> The constellation extends southward to −30°&nbsp;declination. Segments of the ecliptic within Ophiuchus are south of −20°&nbsp;declination (see chart at right).

In contrast to Orion, from November to January (summer in the Southern Hemisphere, winter in the Northern Hemisphere), Ophiuchus is in the daytime sky and thus not visible at most latitudes. However, for much of the [[Arctic Circle]] in the Northern Hemisphere's winter months, the Sun is below the horizon even at midday. Stars (and thus parts of Ophiuchus, especially Rasalhague) are then visible at twilight for a few hours around local noon, low in the south. In the Northern Hemisphere's spring and summer months, when Ophiuchus is normally visible in the night sky, the constellation is actually not visible, because the [[midnight sun]] obscures the stars at those times and places in the Arctic. In countries close to the equator, Ophiuchus appears overhead in June around midnight and in the October evening sky.{{citation needed|date=February 2021}}
{{clear left}}

==Features==

===Stars===
{{See also|List of stars in Ophiuchus}}

The brightest stars in Ophiuchus include [[Alpha Ophiuchi|α Ophiuchi]], called Rasalhague ("head of the serpent charmer"), at magnitude&nbsp;2.07, and [[Eta Ophiuchi|η Ophiuchi]], known as Sabik ("the preceding one"), at magnitude&nbsp;2.43.<ref>Chartrand III, Mark R.; (1983) ''Skyguide: A Field Guide for Amateur Astronomers'', p. 170 ({{ISBN|0-307-13667-1}}).</ref><ref name="Hoffleit 1991">{{cite web | url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HR%202491 | title=Entry for HR 2491 | work=Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) |author1=Hoffleit, D. |author2=Warren, W. H. Jr. | date=1991 | publisher=[[Centre de Données astronomiques de Strasbourg|CDS]] }} ID [http://vizier.u-strasbg.fr/viz-bin/Cat?V/50 V/50].</ref> Alpha Ophiuchi is composed of an A-type (bluish-white) giant star<ref name=aj74_375>{{citation | display-authors=1 | last1=Cowley | first1=A. | last2=Cowley | first2=C. | last3=Jaschek | first3=M. | last4=Jaschek | first4=C. | title=A study of the bright A stars. I. A catalogue of spectral classifications | journal=Astronomical Journal | volume=74 | pages=375–406 |date=April 1969 | doi=10.1086/110819 | bibcode=1969AJ.....74..375C }}</ref> and a [[K-type main sequence star]].<ref name=apj726_2_104>{{citation | display-authors=1 | last1=Hinkley | first1=Sasha | last2=Monnier | first2=John D. | last3=Oppenheimer | first3=Ben R. | last4=Roberts | first4=Lewis C. Jr. | last5=Ireland | first5=Michael | last6=Zimmerman | first6=Neil | last7=Brenner | first7=Douglas | last8=Parry | first8=Ian R. | last9=Martinache | first9=Frantz | title=Establishing α Oph as a Prototype Rotator: Improved Astrometric Orbit | journal=The Astrophysical Journal | volume=726 | issue=2 | page=104 |date=January 2011 | doi=10.1088/0004-637X/726/2/104 | bibcode=2011ApJ...726..104H |arxiv = 1010.4028 | s2cid=50830196 | url=http://authors.library.caltech.edu/21951/1/Hinkley2011p12486Astrophys_J.pdf }}</ref> The primary is a rapid rotator<ref name=monnierrasalhague>{{cite journal|doi=10.1088/0004-637X/725/1/1192|arxiv=1012.0787|title=Rotationally Modulated g-modes in the Rapidly Rotating δ Scuti Star Rasalhague (α Ophiuchi)|journal=The Astrophysical Journal|volume=725|issue=1|pages=1192–1201|year=2010|last1=Monnier|first1=J. D|last2=Townsend|first2=R. H. D|last3=Che|first3=X|last4=Zhao|first4=M|last5=Kallinger|first5=T|last6=Matthews|first6=J|last7=Moffat|first7=A. F. J|bibcode=2010ApJ...725.1192M|s2cid=51105576}}</ref> with an inclined axis of rotation.<ref name=rmaa38_117>{{citation | display-authors=1 | last1=Zhao | first1=M. | last2=Monnier | first2=J. D. | last3=Pedretti | first3=E. | last4=Thureau | first4=N. | last5=Mérand | first5=A. | last6=Ten Brummelaar | first6=T. | last7=McAlister | first7=H. | last8=Ridgway | first8=S. T. | last9=Turner | first9=N. | title=Imaging and Modeling Rapid Rotators: α Cep and α Oph | department=The Interferometric View on Hot Stars | editor1-first=Th. | editor1-last=Rivinius | editor2-first=M. | editor2-last=Curé | journal=Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias | volume=38 | pages=117–118 |date=February 2010 | bibcode=2010RMxAC..38..117Z }}</ref> Eta Ophiuchi is a binary system.<ref name=aj133_4_1209>{{citation | last1=Docobo | first1=J. A. | last2=Ling | first2=J. F. | title=Orbits and System Masses of 14 Visual Double Stars with Early-Type Components | journal=The Astronomical Journal | volume=133 | issue=4 | pages=1209–1216 |date=April 2007 | doi=10.1086/511070 | bibcode=2007AJ....133.1209D | s2cid=120821801 | doi-access=free }}</ref> Other bright stars in the constellation include [[Beta Ophiuchi|β Ophiuchi]], Cebalrai ("dog of the shepherd")<ref>{{cite book |author1=Paul Kunitzsch |author2=Tim Smart |title=A Dictionary of Modern Star Names: A Short Guide to 254&nbsp;Star Names and Their Derivations |url=https://books.google.com/books?id=XVspPwAACAAJ |year=2006 |publisher=[[Sky Publishing Corporation]] |isbn=978-1-931559-44-7 |page=44}}</ref> and [[Lambda Ophiuchi|λ Ophiuchi]], or Marfik ("the elbow").<ref>Chartrand, at p. 170.</ref> Beta Ophiuchi is an evolved [[red giant]] star that is slightly more massive than the Sun.<ref name=aaa352_555>{{citation | last1=Allende Prieto | first1=C. | last2=Lambert | first2=D. L. | title=Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures | journal=[[Astronomy and Astrophysics]] | volume=352| pages=555–562 | year=1999 | doi=10.1051/0004-6361/200811242 | bibcode=1999A&A...352..555A | arxiv=0809.0359 | s2cid=14531031 }}</ref><ref name=aaa480_1_91>{{citation | display-authors=1 | last1=Soubiran | first1=C. | last2=Bienaymé | first2=O. | last3=Mishenina | first3=T. V. | last4=Kovtyukh | first4=V. V. | title=Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants | journal=Astronomy and Astrophysics | year=2008 | volume=480 | issue=1 | pages=91–101 | bibcode=2008A&A...480...91S | doi=10.1051/0004-6361:20078788 |arxiv = 0712.1370 | s2cid=16602121 }}</ref> Lambda Ophiuchi is a binary star system with the primary being more massive and luminous than the Sun.<ref name=zorec2012>{{cite journal
 | last1=Zorec | first1=J. | last2=Royer | first2=F.
 | last3=Asplund | first3=Martin | last4=Cassisi | first4=Santi
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 | bibcode=2012A&A...537A.120Z | arxiv=1201.2052
 | doi=10.1051/0004-6361/201117691 | s2cid=55586789 }}</ref><ref name=aaa388>{{cite journal |author1=Lastennet, E. |author2=Fernandes, J. |author3=Lejeune, Th. | title=A revised HRD for individual components of binary systems from BaSeL BVRI synthetic photometry. Influence of interstellar extinction and stellar rotation | journal=Astronomy and Astrophysics | volume=388 | pages=309–319 |date=June 2002 | doi=10.1051/0004-6361:20020439 | bibcode=2002A&A...388..309L |arxiv = astro-ph/0203341 |s2cid=14376211 }}</ref>

[[RS Ophiuchi]] is part of a class called recurrent [[nova]]e, whose brightness increase at irregular intervals by hundreds of times in a period of just a few days. It is thought to be at the brink of becoming a type-1a [[supernova]].<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/5204676.stm |title=Star 'soon to become supernova' |publisher=[[BBC News]] |date=23 July 2006}}</ref> It erupts around every 15 years and usually has a magnitude of around 5.0 during eruptions, most recently in 2021.<ref>{{Cite web|title=[vsnet-alert 26131] Outburst of RS Ophiuchi|url=http://ooruri.kusastro.kyoto-u.ac.jp/mailarchive/vsnet-alert/26131|access-date=2021-08-09|website=ooruri.kusastro.kyoto-u.ac.jp}}</ref><ref>{{Cite web|title=ATel #14834: Fermi-LAT Gamma-ray Detection of the Recurrent Nova RS Oph|url=https://astronomerstelegram.org/?read=14834|access-date=2021-08-09|website=ATel}}</ref>

[[Barnard's Star]], one of the [[list of nearest stars|nearest stars]] to the [[Solar System]] (the only stars closer are the [[Alpha Centauri]] [[binary star]] system and [[Proxima Centauri]]), lies in Ophiuchus. It is located to the left of β and just north of the V-shaped group of stars in an area that was once occupied by the now-obsolete constellation of [[Taurus Poniatovii]] (Poniatowski's Bull). It is thought that an exoplanet orbits around the star,<ref name=BarnardPlanet>{{cite journal
          | last1   = Ribas                | first1   = I.
          | last2  = Tuomi                | first2  = M.
          | last3  = Reiners              | first3  = Ansgar
          | last4  = Butler               | first4  = R. P.
          | last5  = Morales              | first5  = J. C.
          | last6  = Perger               | first6  = M.
          | last7  = Dreizler             | first7  = S.
          | last8  = Rodríguez-López      | first8  = C.
          | last9  = González Hernández   | first9  = J. I.
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          | last12 = Trifonov             | first12 = T.
          | last13 = Vogt                 | first13 = S. S.
          | last14 = Caballero            | first14 = J. A.
          | last15 = Hatzes               | first15 = A.
          | last16 = Herrero              | first16 = E.
          | last17 = Jeffers              | first17 = S. V.
          | last18 = Lafarga              | first18 = M.
          | last19 = Murgas               | first19 = F.
          | last20 = Nelson               | first20 = R. P.
          | last21 = Rodríguez            | first21 = E.
          | last22 = Strachan             | first22 = J. B. P.
          | last23 = Tal-Or               | first23 = L.
          | last24 = Teske                | first24 = J.
          | last25 = Toledo-Padrón        | first25 = B.
          | last26 = Zechmeister          | first26 = M.
          | last27 = Quirrenbach          | first27 = A.
          | last28 = Amado                | first28 = P. J.
          | last29 = Azzaro               | first29 = M.
          | last30 = Béjar                | first30 = V. J. S.
          | last31 = Barnes               | first31 = J. R.
          | last32 = Berdiñas             | first32 = Z. M.
          | last33 = Burt                 | first33 = J.
          | last34 = Coleman              | first34 = G.
          | last35 = Cortés-Contreras     | first35 = M.
          | last36 = Crane                | first36 = J.
          | last37 = Engle                | first37 = S. G.
          | last38 = Guinan               | first38 = E. F.
          | last39 = Haswell              | first39 = C. A.
          | last40 = Henning              | first40 = Th.
          | last41 = Holden               | first41 = B.
          | last42 = Jenkins              | first42 = J.
          | last43 = Jones                | first43 = H. R. A.
          | last44 = Kaminski             | first44 = A.
          | last45 = Kiraga               | first45 = M.
          | last46 = Kürster              | first46 = Martin
          | last47 = Lee                  | first47 = M. H.
          | last48 = López-González       | first48 = M. J.
          | last49 = Montes               | first49 = D.
          | last50 = Morin                | first50 = J.
          | last51 = Ofir                 | first51 = A.
          | last52 = Pallé                | first52 = E.
          | last53 = Rebolo               | first53 = Rafael
          | last54 = Reffert              | first54 = S.
          | last55 = Schweitzer           | first55 = A.
          | last56 = Seifert              | first56 = W.
          | last57 = Shectman             | first57 = S. A.
          | last58 = Staab                | first58 = D.
          | last59 = Street               | first59 = R. A.
          | last60 = Suárez Mascareño     | first60 = A.
          | last61 = Tsapras              | first61 = Y.
          | last62 = Wang                 | first62 = S. X.
          | last63 = Anglada-Escudé       | first63 = G.
          | display-authors    = 4
          | date              = 2018-11-14
          | title             = A candidate super-Earth planet orbiting near the snow line of Barnard's star
          | url               = https://www.eso.org/public/archives/releases/sciencepapers/eso1837/eso1837a.pdf
          | url-status        = live
          | journal           = [[Nature (journal)|Nature]]
          | publisher         = [[Holtzbrinck Publishing Group]]
          | volume            = 563
          | issue             = 7731
          | pages             = 365–368
          | arxiv             = 1811.05955
          | bibcode           = 2018Natur.563..365R
          | doi               = 10.1038/s41586-018-0677-y
          | issn              = 0028-0836
          | oclc              = 716177853
          | archive-url       = https://web.archive.org/web/20190326185022/https://www.eso.org/public/archives/releases/sciencepapers/eso1837/eso1837a.pdf
          | archive-date      = 2019-03-26
          | pmid              = 30429552
     | hdl = 2299/21132
 | s2cid = 256769911
 }}</ref> but later studies have refuted this claim.<ref name=Lubin2021>{{cite journal | last1=Lubin | first1=Jack | last2=Robertson | first2=Paul | last3=Stefansson | first3=Gudmundur | last4=Ninan | first4=Joe | last5=Mahadevan | first5=Suvrath | last6=Endl | first6=Michael | last7=Ford | first7=Eric | last8=Wright | first8=Jason T. | last9=Beard | first9=Corey | last10=Bender | first10=Chad | last11=Cochran | first11=William D. | last12=Diddams | first12=Scott A. | last13=Fredrick | first13=Connor | last14=Halverson | first14=Samuel | last15=Kanodia | first15=Shubham | last16=Metcalf | first16=Andrew J. | last17=Ramsey | first17=Lawrence | last18=Roy | first18=Arpita | last19=Schwab | first19=Christian | last20=Terrien | first20=Ryan |display-authors=3 | title=Stellar Activity Manifesting at a One-year Alias Explains Barnard b as a False Positive | journal=The Astronomical Journal | publisher=American Astronomical Society | volume=162 | issue=2 | date=15 July 2021 | doi=10.3847/1538-3881/ac0057|issn=0004-6256 | pages=61 | arxiv=2105.07005| bibcode=2021AJ....162...61L | s2cid=234741985 | doi-access=free }}</ref> In 1998, an intense flare was observed.<ref name=PaulsonBarnard>{{cite journal|first1=Diane B.|last1=Paulson|year=2006|title=Optical Spectroscopy of a Flare on Barnard's Star|journal=[[Publications of the Astronomical Society of the Pacific]]|volume=118|issue=1|page=227|doi=10.1086/499497|last2=Allred|first2=Joel C.|last3=Anderson|first3=Ryan B.|last4=Hawley|first4=Suzanne L.|last5=Cochran|first5=William D.|last6=Yelda|first6=Sylvana|bibcode=2006PASP..118..227P|arxiv=astro-ph/0511281|s2cid=17926580}}</ref><ref name=BenedictBarnard>{{cite journal|last1=Benedict|first1=G. Fritz|year=1998|title=Photometry of Proxima Centauri and Barnard's star using Hubble Space Telescope fine guidance senso 3|journal=The Astronomical Journal|bibcode=1998AJ....116..429B|volume=116|issue=1|page=429|doi=10.1086/300420|last2=McArthur|first2=Barbara|last3=Nelan|first3=E.|last4=Story|first4=D.|last5=Whipple|first5=A. L.|last6=Shelus|first6=P. J.|last7=Jefferys|first7=W. H.|last8=Hemenway|first8=P. D.|last9=Franz|first9=Otto G.|last10=Wasserman|first10=L. H.|last11=Duncombe|first11=R. L.|last12=Van Altena|first12=W.|last13=Fredrick|first13=L. W.|arxiv=astro-ph/9806276|s2cid=15880053}}</ref> The star has also been a target of plans for interstellar travel such as [[Project Daedalus]].<ref name=Daedalus76>{{cite journal|last1=Bond|first1=A.|last2=Martin|first2=A. R.|name-list-style=amp|year=1976|title=Project Daedalus – The mission profile|journal=[[Journal of the British Interplanetary Society]]|url=http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=A7618970AH&q=project+daedalus&uid=788304424&setcookie=yes|volume=9|issue=2|page=101|access-date=15 August 2006|bibcode=1976JBIS...29..101B|url-status=dead|archive-url=https://web.archive.org/web/20071020144727/http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=A7618970AH&q=project+daedalus&uid=788304424&setcookie=yes|archive-date=20 October 2007}}</ref><ref name=DarlingDaedalus>{{cite encyclopedia|first=David|last=Darling|url=http://www.daviddarling.info/encyclopedia/D/Daedalus.html|title=Daedalus, Project|date=July 2005|encyclopedia=The Encyclopedia of Astrobiology, Astronomy, and Spaceflight|access-date=10 August 2006|archive-url=https://web.archive.org/web/20060831043940/http://www.daviddarling.info/encyclopedia/D/Daedalus.html|archive-date=31 August 2006|url-status=live}}</ref> In 2005, astronomers using data from the [[Green Bank Telescope]] discovered a [[superbubble]] so large that it extends beyond the plane of the galaxy.<ref name='huge superbubble'>{{cite news |title=Huge 'Superbubble' of Gas Blowing Out of Milky Way |date=13 January 2006 |url=http://www.physorg.com/news9882.html|work=[[PhysOrg.com]] |access-date=4 July 2008}}</ref> It is called the [[Ophiuchus Superbubble]].

In April 2007, [[astronomer]]s announced that the [[Sweden|Swedish]]-built [[Odin (satellite)|Odin satellite]] had made the first detection of clouds of [[molecule|molecular]] [[oxygen]] in space, following observations in the constellation Ophiuchus.<ref>{{cite web |url=https://www.sciencedaily.com/releases/2007/04/070417080835.htm |title=Molecular Oxygen Detected for the First Time in the Interstellar Medium |access-date=28 September 2016}}</ref> The [[SN 1604|supernova of 1604]] was first observed on 9&nbsp;October 1604, near θ&nbsp;Ophiuchi. [[Johannes Kepler]] saw it first on 16&nbsp;October and studied it so extensively that the [[supernova]] was subsequently called ''Kepler's Supernova''. He published his findings in a book titled ''De stella nova in pede Serpentarii'' (''On the New Star in Ophiuchus's Foot''). [[Galileo Galilei|Galileo]] used its brief appearance to counter the [[Aristotle|Aristotelian]] [[dogma]] that the heavens are changeless. It was a Type Ia supernova<ref name = "Reynolds2007">{{Cite journal | last1 = Reynolds | first1 = S. P. | last2 = Borkowski | first2 = K. J. | last3 = Hwang | first3 = U. | last4 = Hughes | first4 = J. P. | last5 = Badenes | first5 = C. | last6 = Laming | first6 = J. M. | last7 = Blondin | first7 = J. M. | date = 2 October 2007 | title = A Deep ''Chandra'' Observation of Kepler's Supernova Remnant: A Type Ia Event with Circumstellar Interaction | journal = [[The Astrophysical Journal]] | volume = 668 | issue = 2 | pages = L135–L138 | doi = 10.1086/522830 |doi-access=free|arxiv = 0708.3858 |bibcode = 2007ApJ...668L.135R |bibcode-access=free}}</ref> and the most recent Milky Way supernova visible to the unaided eye.<ref>{{cite web|title=Kepler's Supernova: Recently Observed Supernova|url=http://www.universeforfacts.com/2013/12/keplers-supernova-sn-1064-most-recently.html|archive-url=https://web.archive.org/web/20190104220659/http://www.universeforfacts.com/2013/12/keplers-supernova-sn-1064-most-recently.html|url-status=dead|archive-date=4 January 2019|website=Universe for Facts|access-date=21 December 2014}}</ref> In 2009 it was announced that [[GJ 1214]], a star in Ophiuchus, undergoes repeated, cyclical dimming with a period of about 1.5&nbsp;days consistent with the transit of a small orbiting planet.<ref>{{cite journal |last1=Charbonneau |first1=David |display-authors=etal <!-- Zachory K. Berta, Jonathan Irwin, Christopher J. Burke, Philip Nutzman, Lars A. Buchhave, Christophe Lovis, Xavier Bonfils, David W. Latham, Stéphane Udry, Ruth A. Murray-Clay, Matthew J. Holman, Emilio E. Falco, Joshua N. Winn, Didier Queloz, Francesco Pepe, Michel Mayor, Xavier Delfosse, Thierry Forveille --> |title=A super-Earth transiting a nearby low-mass star |journal=Nature |volume=462 |issue=7275 |pages=891–894 |doi=10.1038/nature08679 |pmid=20016595 |date=December 2009 |arxiv=0912.3229 |bibcode=2009Natur.462..891C|s2cid=4360404 }}</ref> The planet's low density (about 40% that of Earth) suggests that the planet may have a substantial component of low-density gas—possibly [[hydrogen]] or [[steam]].<ref>{{cite journal |last1=Rogers |first1=Leslie A. |last2=Seager |first2=Sara |title=Three Possible Origins for the Gas Layer on GJ&nbsp;1214b |journal=The Astrophysical Journal |volume=716 |issue=2 |pages=1208–1216 |doi=10.1088/0004-637x/716/2/1208 |bibcode=2010ApJ...716.1208R |arxiv=0912.3243 |year=2010|s2cid=15288792 }}</ref> The proximity of this star to Earth (42&nbsp;light years) makes it a tempting target for further observations.{{according to whom|date=July 2019}} The host star emits X-rays which could have removed mass from the exoplanet.<ref name=Lalitha2014>{{cite journal
 | title=X-Ray Emission from the Super-Earth Host GJ 1214
 | display-authors=1
 | last1=Lalitha | first1=S.
 | last2=Poppenhaeger | first2=K.
 | last3=Singh | first3=K. P.
 | last4=Czesla | first4=S.
 | last5=Schmitt | first5=J. H. M. M.
 | journal=The Astrophysical Journal Letters
 | volume=790
 | issue=1
 | id=L11
 | pages=5
 | date=July 2014
 | doi=10.1088/2041-8205/790/1/L11
 | bibcode=2014ApJ...790L..11L
 |arxiv = 1407.2741 | s2cid=118774018
 }}</ref> In April 2010, the naked-eye star [[Zeta Ophiuchi|ζ Ophiuchi]] was occulted by the asteroid [[824 Anastasia]].<ref>{{cite web |url=http://www.skyandtelescope.com/resources/proamcollab/astroalert/89599442.html |title=Asteroid To Hide Naked-Eye Star |access-date=2019-07-17 |date=31 March 2010 }}</ref><ref>{{cite web |url=http://www.skyandtelescope.com/observing/highlights/89690067.html |title=Asteroid To Hide Bright Star |access-date=2019-07-17|date=31 March 2010 }}</ref><ref name=IOTA>{{cite web |url=http://asteroidoccultation.com/2010_04_si.htm |title=(824) Anastasia / HIP 81377 event on 2010 Apr&nbsp;06, 10:21&nbsp;UT |access-date=2019-07-17 |archive-date=17 July 2019 |archive-url=https://web.archive.org/web/20190717141423/http://asteroidoccultation.com/2010_04_si.htm |url-status=dead }}</ref>

<gallery widths="140px" heights="200px">
Image:OphiuchusCC.jpg|The constellation Ophiuchus as it can be seen by naked eye<ref>{{cite web |url=http://www.allthesky.com/constellations/ophiuchus.html |title=Ophiuchus, the Serpent Bearer – Constellations – Digital Images of the Sky }}</ref>
Image:Kepler Drawing of SN 1604.png|[[Johannes Kepler]]'s drawing depicting the location of the ''stella nova'' in the foot of Ophiuchus
Image:Stjärnbild på Herkules, 1602 - Skoklosters slott - 102426.tif|Hercules and Ophiuchus, 1602 by [[Willem Blaeu]]
</gallery>

===Deep-sky objects===
[[File:Rho Ophiuchi.jpg|thumb|right|Infrared light view of [[Rho Ophiuchi cloud complex|Rho Ophiuchi]] [[molecular cloud]] complex from [[NASA]]]]
[[File:Rho Ophiucus Widefield.jpg|thumb|right|Photo from Rogelio Bernal Andreo of the [[Rho Ophiuchi cloud complex|Rho Ophiuchi]] [[molecular cloud]] complex]]

Ophiuchus contains several [[star cluster]]s, such as [[Open Cluster IC 4665|IC&nbsp;4665]], [[NGC 6633]], [[Globular Cluster M9|M9]], [[Globular Cluster M10|M10]], [[Globular Cluster M12|M12]], [[Globular Cluster M14|M14]], [[Globular Cluster M19|M19]], [[Globular Cluster M62|M62]], and [[Globular Cluster M107|M107]], as well as the [[nebula]] IC&nbsp;4603-4604.

[[Messier 9|M9]] is a globular cluster which may have an extra-galactic origin.<ref name=mnras434_2_1220>{{citation
 | display-authors=1 | last1=Arellano Ferro | first1=A.
 | last2=Bramich | first2=D. M. | last3=Figuera Jaimes | first3=R.
 | last4=Giridhar | first4=Sunetra | last5=Kains | first5=N.
 | last6=Kuppuswamy | first6=K. | last7=Jørgensen | first7=U. G.
 | last8=Alsubai | first8=K. A. | last9=Andersen | first9=J. M.
 | last10=Bozza | first10=V. | last11=Browne | first11=P.
 | last12=Calchi Novati | first12=S. | last13=Damerdji | first13=Y.
 | last14=Diehl | first14=C. | last15=Dominik | first15=M.
 | last16=Dreizler | first16=S. | last17=Elyiv | first17=A.
 | last18=Giannini | first18=E. | last19=Harpsøe | first19=K.
 | last20=Hessman | first20=F. V. | last21=Hinse | first21=T. C.
 | last22=Hundertmark | first22=M. | last23=Juncher | first23=D.
 | last24=Kerins | first24=E. | last25=Korhonen | first25=H.
 | last26=Liebig | first26=C. | last27=Mancini | first27=L.
 | last28=Mathiasen | first28=M. | last29=Penny | first29=M. T.
 | last30=Rabus | first30=M. | last31=Rahvar | first31=S.
 | last32=Ricci | first32=D. | last33=Scarpetta | first33=G.
 | last34=Skottfelt | first34=J. | last35=Snodgrass | first35=C.
 | last36=Southworth | first36=J. | last37=Surdej | first37=J.
 | last38=Tregloan-Reed | first38=J. | last39=Vilela | first39=C.
 | last40=Wertz | first40=O. | last41=Mindstep Consortium 
 | title=A detailed census of variable stars in the globular cluster NGC 6333 (M9) from CCD differential photometry
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=434 | issue=2 | pages=1220–1238 | date=September 2013
 | doi=10.1093/mnras/stt1080 | doi-access=free | bibcode=2013MNRAS.434.1220A 
 | arxiv=1306.3206 | postscript=. }}</ref> [[Messier 10|M10]] is a fairly close [[globular cluster]], only 20,000&nbsp;light-years from Earth. It has a magnitude of 6.6 and is a Shapley class&nbsp;VII cluster. This means that it has "intermediate" concentration; it is only somewhat concentrated towards its center.{{sfn|Levy|2005|pp=153-54}} M12 is a globular cluster which is around 5 kiloparsecs from the Solar System.<ref name=M12Gontcharov>{{cite journal | doi=10.1093/mnras/stab2756 | title=Isochrone fitting of Galactic globular clusters – III. NGC 288, NGC 362, and NGC 6218 (M12) | year=2021 | last1=Gontcharov | first1=George A. | last2=Khovritchev | first2=Maxim Yu | last3=Mosenkov | first3=Aleksandr V. | last4=Il'In | first4=Vladimir B. | last5=Marchuk | first5=Alexander A. | last6=Savchenko | first6=Sergey S. | last7=Smirnov | first7=Anton A. | last8=Usachev | first8=Pavel A. | last9=Poliakov | first9=Denis M. | journal=Monthly Notices of the Royal Astronomical Society | volume=508 | issue=2 | pages=2688–2705| doi-access=free | arxiv=2109.13115 }}</ref> [[Messier 14|M14]] is another globular cluster which is somewhat farther away.<ref name=apj742_1_51>{{citation | display-authors=1 | last1=Boyles | first1=J. | last2=Lorimer | first2=D. R. | last3=Turk | first3=P. J. | last4=Mnatsakanov | first4=R. | last5=Lynch | first5=R. S. | last6=Ransom | first6=S. M. | last7=Freire | first7=P. C. | last8=Belczynski | first8=K. | title=Young Radio Pulsars in Galactic Globular Clusters | journal=The Astrophysical Journal | volume=742 | issue=1 | page=51 |date=November 2011 | doi=10.1088/0004-637X/742/1/51 | bibcode=2011ApJ...742...51B | postscript=. |arxiv = 1108.4402 | s2cid=118649860 }}</ref> Globular cluster M19 is [[spheroid|oblate-shaped]]<ref name=burnham1978>{{citation | first1=Robert | last1=Burnham | title=Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System | volume=2 | series=Dover Books on Astronomy | edition=2nd | publisher=[[Courier Dover Publications]] | date=1978 | isbn=978-0486235684 | page=1263 | url=https://books.google.com/books?id=wB9uZ9lH5bgC&pg=PA1263 | postscript=. }}</ref> with multiple different types of variable stars.<ref name=aj122_5_2587>{{citation | display-authors=1 | last1=Clement | first1=Christine M. | last2=Muzzin | first2=Adam | last3=Dufton | first3=Quentin | last4=Ponnampalam | first4=Thivya | last5=Wang | first5=John | last6=Burford | first6=Jay | last7=Richardson | first7=Alan | last8=Rosebery | first8=Tara | last9=Rowe | first9=Jason | last10=Hogg | first10=Helen Sawyer | title=Variable Stars in Galactic Globular Clusters | journal=The Astronomical Journal | volume=122 | issue=5 | pages=2587–2599 |date=November 2001 | doi=10.1086/323719 | bibcode=2001AJ....122.2587C | postscript=. |arxiv = astro-ph/0108024 | s2cid=38359010 }}</ref> M62 is a globular cluster rich in [[variable star]]s such as [[RR Lyrae variables]]<ref name=Contreras2010>{{citation
 | title=Time-series Photometry of Globular Clusters: M62 (NGC 6266), the Most RR Lyrae-rich Globular Cluster in the Galaxy?
 | last1=Contreras | first1=R. | last2=Catelan | first2=M.
 | last3=Smith | first3=H. A. | last4=Pritzl | first4=B. J.
 | last5=Borissova | first5=J. | last6=Kuehn | first6=C. A.
 | journal=The Astronomical Journal | display-authors=1
 | volume=140 | issue=6 | pages=1766–1786 | date=December 2010
 | doi=10.1088/0004-6256/140/6/1766 | bibcode=2010AJ....140.1766C | arxiv=1009.4206 | s2cid=118515997 }}</ref> and has two generations of stars with different element abundances.<ref name=Milone2015>{{citation
 | title=Helium and multiple populations in the massive globular cluster NGC 6266 (M 62)
 | last1=Milone | first1=A. P.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=446 | issue=2 | pages=1672–1684 | date=January 2015
 | bibcode=2015MNRAS.446.1672M | arxiv=1409.7230
 | doi=10.1093/mnras/stu2198 | doi-access=free | postscript=. }}</ref> M107 is also rich in variable stars.<ref name=McCombs2013>{{citation
 | contribution=Variable Stars in the Globular Cluster M107: The Discovery of a Probable SX Phoenicis
 | last1=McCombs | first1=Thayne | last2=Reinhart | first2=E.
 | last3=Murphy | first3=B. W. | display-authors=1
 | title=AAS Meeting #221 | volume=221 | pages=250.22 | id=250.22 | date=January 2013
 | publisher=American Astronomical Society
 | bibcode=2013AAS...22125022M | postscript=. }}</ref>

The unusual [[galaxy]] merger remnant and [[starburst galaxy]] [[NGC 6240]] is also in Ophiuchus. At a distance of 400&nbsp;million light-years, this "butterfly-shaped" galaxy has two [[supermassive black hole]]s 3,000&nbsp;light-years apart. Confirmation of the fact that both [[active galactic nucleus|nuclei]] contain black holes was obtained by [[Electromagnetic spectrum|spectra]] from the [[Chandra X-ray Observatory]]. Astronomers estimate that the black holes will [[binary black hole|merge]] in another billion years. NGC&nbsp;6240 also has an unusually high rate of [[star formation]], classifying it as a [[starburst galaxy]]. This is likely due to the heat generated by the orbiting black holes and the aftermath of the [[galactic merger|collision]].<ref name="objects">{{cite book |title=300&nbsp;Astronomical Objects: A Visual Reference to the Universe |first1=Jamie |last1=Wilkins |first2=Robert |last2=Dunn |publisher=Firefly Books |date=2006 |location=Buffalo, New York |isbn=978-1-55407-175-3}}</ref> Both have [[active galactic nuclei]].<ref name="komossaetal 2003">
{{cite journal
 | last1  = Komossa  | first1  = Stefanie
 | last2 = Burwitz  | first2 = Vadim
 | last3 = Hasinger | first3 = Guenther
 | last4 = Predehl  | first4 = Peter
 | last5 = Kaastra  | first5 = Jelle S.
 | last6 = Ikebe    | first6 = Yasushi
 | display-authors = 4
 | title           = Discovery of a Binary Active Galactic Nucleus in the Ultraluminous Infrared Galaxy NGC 6240 Using Chandra
 | date            = 2003
 | journal         = [[Astrophysical Journal]]
 | volume          = 582
 | issue           = 1
 | pages           = L15–L19
 | arxiv           = astro-ph/0212099
 | bibcode         = 2003ApJ...582L..15K
 | doi             = 10.1086/346145
| s2cid = 16697327
 }}</ref>

In 2006, a new nearby [[star cluster]] was discovered associated with the 4th magnitude star [[Mu Ophiuchi]].<ref>{{cite journal |title=A New Nearby Candidate Star Cluster in Ophiuchus at d = 170 pc |last=Mamajek |first=Eric E. |date=2006 |journal=Astronomical Journal |volume=132 |issue=5 |pages=2198–2205 |bibcode=2006AJ....132.2198M |doi=10.1086/508205 |arxiv=astro-ph/0609064|s2cid=14070978 }}</ref> The [[Mamajek 2]] cluster appears to be a poor cluster remnant analogous to the [[Ursa Major Moving Group]], but 7&nbsp;times more distant (approximately 170&nbsp;parsecs away). Mamajek&nbsp;2 appears to have formed in the same star-forming complex as the [[NGC 2516]] cluster roughly 135&nbsp;million years ago.<ref>{{cite journal |title=Dynamical Evolution and Spectral Characteristics of the Stellar Group Mamajek&nbsp;2 |last1=Jilinski |first1=Evgueni |last2=Ortega |first2=Vladimir G. |last3=de la Reza |first3=Jorge Ramiro |last4=Drake |first4=Natalia A. |last5=Bazzanella |first5=Bruno |name-list-style=amp |date=2009 |journal=The Astrophysical Journal |volume=691 |issue=1 |pages=212–218 |bibcode=2009ApJ...691..212J |doi=10.1088/0004-637X/691/1/212 |arxiv=0810.1198|s2cid=15570695 }}</ref>

[[Barnard 68]] is a large [[dark nebula]], located 410&nbsp;light-years from Earth. Despite its diameter of 0.4&nbsp;light-years, Barnard&nbsp;68 only has twice the mass of the Sun, making it both very diffuse and very cold, with a temperature of about 16&nbsp;[[kelvin]]s. Though it is currently stable, Barnard&nbsp;68 will eventually collapse, inciting the process of [[star formation]]. One unusual feature of Barnard&nbsp;68 is its vibrations, which have a period of 250,000&nbsp;years. Astronomers speculate that this phenomenon is caused by the [[shock wave]] from a [[supernova]].<ref name="objects"/>  Barnard 68 has blocked thousands of stars visible at other wavelengths<ref>{{cite web |url=http://www.eso.org/public/images/eso9934b/ |title= The Dark Cloud B68 at Different Wavelengths |publisher= [[European Southern Observatory]]|accessdate= January 30, 2012}}</ref> and the distribution of dust in Barnard 68 has been mapped.<ref>
{{cite journal
|title=Seeing the light through the dark
|last1=Alves|first1=João
|last2=Lada|first2=Charles
|last3=Lada|first3=Elizabeth
|journal=The Messenger
|date=March 2001
|volume=103
|pages=15–20
|bibcode=2001Msngr.103....1A
|url=http://www.eso.org/sci/publications/messenger/archive/no.103-mar01/messenger-no103-1-1.pdf
}}</ref><ref>
{{cite journal
|title=Internal structure of a cold dark molecular cloud inferred from the extinction of background starlight
|last1=Alves|first1=João F.
|last2=Lada|first2=Charles J.
|last3=Lada|first3=Elizabeth A.
|journal=Nature
|date=January 2001
|volume=409
|issue=6817
|pages=159–161
|bibcode=2001Natur.409..159A
|doi=10.1038/35051509
|pmid=11196632
|s2cid=4318459 }}</ref>

The space probe [[Voyager 1]], the furthest man-made object from earth, is traveling in the direction of Ophiuchus. It is located between [[α Herculis]], [[α Ophiuchi]] and [[κ Ophiuchi]] at right ascension 17h 13m and declination +12° 25’ (July 2020).<ref>Coordinates available at [https://theskylive.com/voyager1-info The Sky Live].</ref>

In November 2022, the USA's [[National Science Foundation|NSF]] NOIRLab ([[National Optical-Infrared Astronomy Research Laboratory]]) announced the unambiguous identification of the nearest [[stellar black hole]] orbited by a [[G-type main-sequence star]], the system identified as [[Gaia BH1]] at around 1,560 [[light year]]s from the Sun.<ref name="2022-11-04_NSF">[https://noirlab.edu/public/news/noirlab2227/ Astronomers Discover Closest Black Hole to Earth Gemini North telescope on Hawai‘i reveals first dormant, stellar-mass black hole in our cosmic backyard], Dr [[Kareem El-Badry]] et al, USA [[National Science Foundation]] NOIRLab ([[National Optical-Infrared Astronomy Research Laboratory]]), 2022-11-04</ref>

==History and mythology==
There is no evidence of the constellation preceding the [[Classical Greece|classical era]], and in [[Babylonian astronomy]], a "Sitting Gods" constellation seems to have been located in the general area of Ophiuchus. However, Gavin White proposes that Ophiuchus may in fact be remotely descended from this Babylonian constellation, representing [[Nirah]], a serpent-god who was sometimes depicted with his upper half human but with serpents for legs.<ref>White, Gavin; ''Babylonian Star-lore'', Solaria Pubs, 2008, p. 187f</ref>

The earliest mention of the constellation is in [[Aratus]], informed by the lost catalogue of [[Eudoxus of Cnidus]] (4th&nbsp;century&nbsp;BCE):<ref>{{cite encyclopedia |author1=Liddell, Henry George |author2=Scott, Robert |dictionary=A Greek-English Lexicon |publisher=perseus.tufts.edu |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Do%29fiou%3Dxos |title=ὀφιοῦχος}}</ref> {{blockquote|To the Phantom's back the [[Corona Australis|Crown]] is near, but by his head mark near at hand the head of Ophiuchus, and then from it you can trace the starlit Ophiuchus himself: so brightly set beneath his head appear his gleaming shoulders. They would be clear to mark even at the midmonth moon, but his hands are not at all so bright; for faint runs the gleam of stars along on this side and on that. Yet they too can be seen, for they are not feeble. Both firmly clutch the [[Serpens|Serpent]], which encircles the waist of Ophiuchus, but he, steadfast with both his feet well set, tramples a huge monster, even the [[Scorpio (astrology)|Scorpio]]n, standing upright on his eye and breast. Now the Serpent is wreathed about his two hands – a little above his right hand, but in many folds high above his left.<ref>translation by Mair, Alexander W.; & Mair, Gilbert R.; Loeb Classical Library, volume 129, William Heinemann, London, 1921 [http://www.theoi.com/Text/AratusPhaenomena.html theoi.com]</ref>}}

To the [[ancient Greece|ancient Greeks]], the constellation represented the god [[Apollo]] struggling with a huge snake that guarded the [[Oracle of Delphi]].<ref name="Thompson">{{cite book |last=Thompson |first=Robert |title=Illustrated Guide to Astronomical Wonders: From Novice to Master Observer|date=2007|publisher=O'Reilly Media, Inc.|isbn=9780596526856|page=326}}</ref>

Later myths identified Ophiuchus with [[Laocoön]], the [[Troy|Trojan]] priest of [[Poseidon]], who warned his fellow Trojans about the [[Trojan Horse]] and was later slain by a pair of sea serpents sent by the gods to punish him.<ref name="Thompson"/> According to [[Roman era]] mythography,<ref>Hyginus, ''Astronomica'' 2, 14, Latin Mythography, 2nd&nbsp;century&nbsp;AD</ref> the figure represents the healer [[Asclepius]], who learned the secrets of keeping death at bay after observing one serpent bringing another healing herbs. To prevent the entire human race from becoming [[Immortality|immortal]] under Asclepius' care, [[Jupiter (mythology)|Jupiter]] killed him with a bolt of [[lightning]], but later placed his image in the heavens to honor his good works. In medieval [[Islamic astronomy]] ([[Azophi]]'s ''[[Book of Fixed Stars|Uranometry]]'', 10th century), the constellation was known as ''Al-Ḥawwa''', "the snake-charmer".<ref>{{Cite web|title=Snake-Charmer|url=https://brickthology.com/category/snake-charmer/|access-date=2022-02-01|website=Brickthology|language=en}}</ref>

[[Aratus]] describes Ophiuchus as trampling on [[Scorpius]] with his feet. This is depicted in Renaissance to Early Modern [[star chart]]s, beginning with [[Albrecht Dürer]] in 1515; in some depictions (such as that of [[Johannes Kepler]] in ''[[De Stella Nova]]'', 1606), Scorpius also seems to threaten to sting Serpentarius in the foot. This is consistent with [[Azophi]], who already included [[Psi Ophiuchi|ψ&nbsp;Oph]] and [[Omega Ophiuchi|ω&nbsp;Oph]] as the snake-charmer's "left foot", and [[Theta Ophiuchi|θ Oph]] and [[Omicron Ophiuchi|ο&nbsp;Oph]] as his "right foot", making Ophiuchus a [[zodiacal constellation]] at least as regards his feet.<ref>{{cite web |url=http://www.icoproject.org/cons.html |title=Manuscript reproduction |access-date=2019-07-17 |archive-date=6 May 2019 |archive-url=https://web.archive.org/web/20190506142015/http://www.icoproject.org/cons.html |url-status=dead }}</ref> This arrangement has been taken as symbolic in later literature and placed in relation to the words spoken by God to the serpent in the [[Garden of Eden]] (Genesis 3:15).<ref>[[Edward Walter Maunder|Maunder, Edward Walter]]; ''Astronomy of the Bible'', 1908, p. 164f</ref>

<gallery widths="200px" heights="150px">
File:Azophi Ophiuchus.jpg|Ophiuchus in a manuscript copy of [[Azophi]]'s [[Book of Fixed Stars|''Uranometry'']], 18th&nbsp;century copy of a manuscript prepared for [[Ulugh Beg]] in 1417 (note that as in all pre-modern [[star chart]]s, the constellation is mirrored, with [[Serpens Caput]] on the left and [[Serpens Cauda]] on the right).
File:Sidney Hall - Urania's Mirror - Taurus Poniatowski, Serpentarius, Scutum Sobiesky, and Serpens.jpg|Ophiuchus holding the serpent, Serpens, as depicted in ''[[Urania's Mirror]]'', a set of constellation cards published in London c.&nbsp;1825. Above the tail of the serpent is the now-obsolete constellation [[Taurus Poniatovii]] while below it is [[Scutum (constellation)|Scutum]].
</gallery>

==Zodiac==
{{main|Ophiuchus (astrology)}}

Ophiuchus is one of the 13 constellations that cross the [[ecliptic]].<ref>Shapiro, Lee T. [http://spaceplace.nasa.gov/starfinder3/ "Constellations in the zodiac"], in ''The Space Place'' (NASA, last updated 22 July 2011)</ref> It has sometimes been suggested as the "13th sign of the [[zodiac]]". However, this confuses [[zodiac sign|zodiac or astrological signs]] with [[constellations]].<ref>{{cite web|url=https://earthsky.org/sky-archive/ophiuchus-highest-on-august-evenings-2|title=Ophiuchus, 13th constellation of zodiac|work= Earth Sky | access-date = 2019-07-19}}</ref> The signs of the zodiac are a 12-fold division of the ecliptic, so that each sign spans 30° of celestial longitude, approximately the distance the Sun travels in a month, and (in the Western tradition) are aligned with the seasons so that the [[March equinox]] always falls on the boundary between Pisces and Aries.<ref>{{Cite web|last=Gleason|first=Edward|title=Why is the vernal equinox called the "First Point of Aries" when the Sun is actually in Pisces on this date? {{!}} Planetarium|url=https://usm.maine.edu/planet/why-vernal-equinox-called-first-point-aries-when-sun-actually-pisces-date|access-date=2022-03-25|website=University of Southern Maine}}</ref><ref>{{Cite web|last=Campbell|first=Tina|date=2020-07-15|title=Has your star sign changed following the discovery of a 'new' Zodiac sign?|url=https://metro.co.uk/2020/07/15/what-new-zodiac-sign-ophichius-mean-what-dates-cover-12990848/|access-date=2021-04-29|website=Metro|language=en}}</ref> Constellations, on the other hand, are unequal in size and are based on the positions of the stars. The [[Zodiacal constellation#Constellations|constellations of the zodiac]] have only a loose association with the signs of the zodiac, and do not in general coincide with them.<ref>{{cite web |url=http://astrologyclub.org/ophiuchus-13th-zodiac-sign-no/ |title=Ophiuchus – a 13th&nbsp;Zodiac Sign? No! |work=Astrology Club |access-date=2016-10-18 |date=2 March 2016}}</ref> In Western astrology the constellation of Aquarius, for example, largely corresponds to the sign of Pisces. Similarly, the constellation of Ophiuchus occupies most (29&nbsp;November – 18&nbsp;December<ref>{{cite web |url=http://earthsky.org/constellations/born-between-november-29-and-december-18-heres-your-constellation |title=Born under the sign of Ophiuchus? |date=16 August 2021 |publisher=EarthSky.org}}</ref>) of the sign of Sagittarius (23&nbsp;November – 21&nbsp;December). The differences are due to the fact that the time of year that the Sun passes through a particular zodiac constellation's position has slowly changed (because of the [[Axial precession|precession of the Earth's rotational axis]]) over the centuries from when the [[Babylonians]] originally developed the Zodiac.<ref>{{cite journal |last=Aitken |first=Robert G. |title=Edmund Halley and Stellar Proper Motions |journal=Astronomical Society of the Pacific Leaflets |date=October 1942 |volume=4 |issue=164 |pages=103 |bibcode=1942ASPL....4..103A}}</ref><ref>{{cite web |last=Redd |first=Nola Taylor |title=Constellations: The Zodiac Constellation Names |url=http://www.space.com/15722-constellations.html |publisher=space.com |access-date=3 August 2012}}</ref>

==Citations==
{{Reflist}}

==See also==
* [[Ophiuchus (Chinese astronomy)]]

==References==
* {{cite book |first=David H. |last=Levy |title=Deep Sky Objects |publisher=Prometheus Books |date=2005 |isbn=1-59102-361-0 |url-access=registration |url=https://archive.org/details/deepskyobjects00davi}}
* Ridpath, Ian; and Tirion, Wil; (2007) ''Stars and Planets Guide'', Collins, London; {{ISBN|978-0-00-725120-9}}, Princeton University Press, Princeton; {{ISBN|978-0-691-13556-4}}

==External links==
{{EB1911 poster|Serpentarius}}
{{Commons category|Ophiuchus (constellation)}}
* [http://www.allthesky.com/constellations/ophiuchus/ The Deep Photographic Guide to the Constellations: Ophiuchus]
* [http://www.ianridpath.com/startales/ophiuchus.html Star Tales – Ophiuchus]
* [https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017051 Warburg Institute Iconographic Database (ca 160 medieval and early modern images of Ophiuchus under the Latin name Serpentarius)]

{{Stars of Ophiuchus}}
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{{Zodiac}}
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[[Category:Ophiuchus| ]]
[[Category:Constellations]]
[[Category:Equatorial constellations]]
[[Category:Constellations listed by Ptolemy]]
[[Category:Asclepius in mythology]]