→Perihelion passages: gallery packed
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{{Short description|Periodic comet with 5 year orbit}} |
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{{Infobox Comet |
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{{Infobox comet |
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| name=46P/Wirtanen |
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| name = 46P/Wirtanen |
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| image= [[Image:ESO-Comet Wirtanen.jpg|250px| Credit:[[ESO]]]] |
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| image = Comet 46P Wirtanen on 12 December 2018 (cropped).png |
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| discoverer=[[Carl A. Wirtanen]] |
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| caption = Wirtanen at perihelion on 12 December 2018 |
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| discovery_date=January 17, 1948 |
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| discoverer = [[Carl A. Wirtanen]] |
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| designations=1961 IV; 1960m;<br/>1967 XIV; 1967k;<br/>1974 XI; 1974i;<br/>1986 VI; 1985q;<br/>1991 XVI; 1991s;<br/>46P/1948 A1;<br/>1947 XIII; 1948b;<br/>46P/1954 R2;<br/>1954 XI;<br/>1954j |
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| discovery_date = January 17, 1948 |
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| epoch=September 3, 2002 (JDT 2452520.5)<!--- source: http://www.aerith.net/comet/catalog/0046P/2002.html ---> |
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| designations = 1961 IV; 1960m;<br/>1967 XIV; 1967k;<br/>1974 XI; 1974i;<br/>1986 VI; 1985q;<br/>1991 XVI; 1991s;<br/>46P/1948 A1;<br/>1947 XIII; 1948b;<br/>46P/1954 R2;<br/>1954 XI;<br/>1954j |
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| Earth_moid = {{Convert|0.068|AU|km|abbr=on}}<ref name=jpl-close/> |
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| orbit_ref = <ref name="MPC"/> |
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| semimajor= 3.0943529 [[Astronomical Unit|AU]] |
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| epoch = 2023-02-25<br/>(JDT 2460000.5) |
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| perihelion= 1.0587602 AU |
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| semimajor = 3.091 [[Astronomical Unit|AU]] |
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| aphelion= 5.129946 AU |
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| perihelion = 1.055 AU |
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| eccentricity=0.6578412 |
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| aphelion = 5.127 AU |
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| period= 5.44 [[Julian year (astronomy)|a]] |
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| eccentricity = 0.65867 |
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| inclination= 11.73813° |
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| period = 5.43 [[Julian year (astronomy)|yr]] |
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| last_p=July 9, 2013<ref name="NK2190">{{cite web |
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| inclination = 11.749° |
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|date=2010-04-09 |
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| Earth_moid = {{Convert|0.071|AU|km|abbr=on}}<ref name=jpldata/> |
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|title=46P/Wirtanen (NK 1909) |
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| dimensions = {{val|1.4|u=km}} (radar)<ref name=arizona>{{Cite web|url=https://uanews.arizona.edu/story/ua-researcher-captures-rare-radar-images-comet-46pwirtanen|title = UA Researcher Captures Rare Radar Images of Comet 46P/Wirtanen|date = 20 December 2018}}</ref> |
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|publisher=OAA Computing and Minor Planet Sections |
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| rotation = 8.9 hours<ref name=arizona/> |
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|author=Syuichi Nakano |
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| last_p = December 12, 2018<ref name=MPC/><br />July 9, 2013<ref name="NK2190">{{cite web|date=2010-04-09|title=46P/Wirtanen (NK 1909)|publisher=OAA Computing and Minor Planet Sections|author=Syuichi Nakano|author-link=Syuichi Nakano|url=http://www.oaa.gr.jp/~oaacs/nk/nk1909.htm|access-date=2012-02-18}}</ref><br />February 2, 2008 |
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|author-link=Syuichi Nakano |
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| next_p = 2024-May-19<ref name=MPC/> |
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|url=http://www.oaa.gr.jp/~oaacs/nk/nk1909.htm |
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|accessdate=2012-02-18}}</ref><br>February 2, 2008 |
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| next_p=2018-Dec-12<ref name=MPC>{{mpc|46p}}</ref> |
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}} |
}} |
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'''46P/Wirtanen''' is a small short-period [[comet]] with a current [[orbit]]al period of 5.4 years. It was the original target for close investigation by the ''[[Rosetta probe|Rosetta]]'' [[spacecraft]], planned by the [[European Space Agency]], but an inability to meet the [[launch window]] caused ''Rosetta'' to be sent to [[67P/Churyumov–Gerasimenko]] instead.<ref>{{cite journal |title=Rosetta Lander—Philae: Implications of an alternative mission |journal=Acta Astronautica |first1=S. |last1=Ulamec |first2=S. |last2=Espinasse |first3=B. |last3=Feuerbacher |first4=M. |last4=Hilchenbach |first5=D. |last5=Moura |first6=H. |last6=Rosenbauer |first7=H. |last7=Scheuerle |first8=R. |last8=Willnecker |display-authors=5 |volume=58 |issue=8 |pages=435–441 |date=April 2006 |doi=10.1016/j.actaastro.2005.12.009 |bibcode=2006AcAau..58..435U}}</ref> It belongs to the [[Jupiter]] family of comets, all of which have [[aphelion|aphelia]] between 5 and 6 [[astronomical unit|AU]]. Its diameter is estimated at {{convert|1.2|km|mi}}. |
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{| class=wikitable style="text-align:center; font-size:11px; float:right; margin:2px" |
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|- bgcolor= style="font-size: smaller;" |
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| colspan="8" style="text-align:center;"|'''Perihelion distance<br/>at different epochs'''<ref name="Kinoshita"/> |
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|- |
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! [[Epoch (astronomy)|Epoch]] !! [[Perihelion]]<br/>([[Astronomical unit|AU]]) |
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|- |
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| 1967 || 1.61 |
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|- |
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| 1974 || 1.26 |
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|- |
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| 1986 || 1.08 |
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|- |
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| 2013 || 1.05 |
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|- |
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| 2035 || 1.08 |
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|- |
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| 2046 || 1.22 |
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|- |
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| 2059 || 1.98 |
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|- |
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| 2095 || 2.01 |
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|} |
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'''46P/Wirtanen''' is a small short-period [[comet]] with a current [[orbit]]al period of 5.4 years.<ref name="NASA-20191203" /><ref name="UM-20191203" /> It was the original target for close investigation by the ''[[Rosetta probe|Rosetta]]'' [[spacecraft]], planned by the [[European Space Agency]], but an inability to meet the [[launch window]] caused ''Rosetta'' to be sent to [[67P/Churyumov–Gerasimenko]] instead.<ref>{{cite journal |title=Rosetta Lander—Philae: Implications of an alternative mission |journal=Acta Astronautica |first1=S. |last1=Ulamec |first2=S. |last2=Espinasse |first3=B. |last3=Feuerbacher |first4=M. |last4=Hilchenbach |first5=D. |last5=Moura |first6=H. |last6=Rosenbauer |first7=H. |last7=Scheuerle |first8=R. |last8=Willnecker |display-authors=5 |volume=58 |issue=8 |pages=435–441 |date=April 2006 |doi=10.1016/j.actaastro.2005.12.009 |bibcode=2006AcAau..58..435U}}</ref> It belongs to the [[Jupiter]] family of comets, all of which have [[aphelion|aphelia]] between 5 and 6 [[astronomical unit|AU]]. Its diameter is estimated at {{convert|1.4|km|mi|sigfig=1}}. In December 2019, astronomers reported capturing an outburst of the comet in substantial detail by the [[TESS|TESS space telescope]].<ref name="NASA-20191203">{{cite news |author=Goddard Space Flight Center |author-link=Goddard Space Flight Center |title=NASA's exoplanet-hunting mission catches a natural comet outburst in unprecedented detail |url=https://www.eurekalert.org/pub_releases/2019-12/nsfc-nem120319.php |date=3 December 2019 |work=[[EurekAlert!]] |access-date=3 December 2019 }}</ref><ref name="UM-20191203">{{cite news |author=University of Maryland |author-link=University of Maryland |title=UMD astronomers catch a natural comet outburst in unprecedented detail - Data from NASA's Transiting Exoplanet Survey Satellite (TESS) reveal start-to-finish sequence of an outburst from comet 46P/Wirtanen |url=https://www.eurekalert.org/pub_releases/2019-12/uom-uac120319.php |date=3 December 2019 |work=[[EurekAlert!]] |access-date=3 December 2019 }}</ref> |
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== Discovery == |
== Discovery == |
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46P/Wirtanen was discovered photographically on January 17, 1948, by the American astronomer [[Carl A. Wirtanen]]. The plate was exposed on January 15 during a stellar proper motion survey for the [[Lick Observatory]]. Due to a limited number of initial observations, it took more than a year to recognize this object as a short-period comet. |
46P/Wirtanen was discovered photographically on January 17, 1948, by the American astronomer [[Carl A. Wirtanen]].<ref name=kronk/> The plate was exposed on January 15 during a stellar proper motion survey for the [[Lick Observatory]]. Due to a limited number of initial observations, it took more than a year to recognize this object as a short-period comet. |
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== Perihelion passages == |
== Perihelion passages == |
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The July 2013 perihelion passage was not favorable, only reaching a magnitude of 14.7.<ref name="Comet 46P/Wirtanen Information">{{Cite web|url=https://theskylive.com/46p-info|title=Comet 46P/Wirtanen Information|website=theskylive.com|access-date=2017-11-26}}</ref> Between January 23 and September 26 of 2013, the comet had an [[Elongation (astronomy)|elongation]] less than 20 degrees from the Sun. |
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On 16 December 2018 the comet passed {{Convert|0.07746|AU|e6km e6mi LD|abbr=unit|lk=on|sigfig=3}} from Earth,<ref name=jpldata/> marking one of the 10 closest comet flybys of Earth in 70 years.<ref name=JPL-7306/> The comet reached an estimated magnitude of 3.9,<ref>{{cite web |title=Brightest comets seen since 1935 |url=http://www.icq.eps.harvard.edu/brightest.html |website=www.icq.eps.harvard.edu |access-date=20 April 2023}}</ref> making this pass the brightest one predicted, and the brightest close approach for the next 20 years.<ref name="Comet 46P/Wirtanen Information"/> The comet experienced six outbursts, with the comet brightening by −0.2 to −1.6 magnitudes.<ref>{{cite journal |last1=Kelley |first1=Michael S. P. |last2=Farnham |first2=Tony L. |last3=Li |first3=Jian-Yang |last4=Bodewits |first4=Dennis |last5=Snodgrass |first5=Colin |last6=Allen |first6=Johannes |last7=Bellm |first7=Eric C. |last8=Coughlin |first8=Michael W. |last9=Drake |first9=Andrew J. |last10=Duev |first10=Dmitry A. |last11=Graham |first11=Matthew J. |last12=Kupfer |first12=Thomas |last13=Masci |first13=Frank J. |last14=Reiley |first14=Dan |last15=Walters |first15=Richard |last16=Dominik |first16=M. |last17=Jørgensen |first17=U. G. |last18=Andrews |first18=A. E. |last19=Bach-Møller |first19=N. |last20=Bozza |first20=V. |last21=Burgdorf |first21=M. J. |last22=Campbell-White |first22=J. |last23=Dib |first23=S. |last24=Fujii |first24=Y. I. |last25=Hinse |first25=T. C. |last26=Hundertmark |first26=M. |last27=Khalouei |first27=E. |last28=Longa-Peña |first28=P. |last29=Rabus |first29=M. |last30=Rahvar |first30=S. |last31=Sajadian |first31=S. |last32=Skottfelt |first32=J. |last33=Southworth |first33=J. |last34=Tregloan-Reed |first34=J. |last35=Unda-Sanzana |first35=E. |display-authors=5|title=Six Outbursts of Comet 46P/Wirtanen |journal=The Planetary Science Journal |date=1 August 2021 |volume=2 |issue=4 |pages=131 |doi=10.3847/PSJ/abfe11|arxiv=2105.05826 |doi-access=free |bibcode=2021PSJ.....2..131K }}</ref> |
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The 2013 perihelion passage was not favorable, only reaching a magnitude of 14.7.<ref>{{Cite web|url=https://theskylive.com/46p-info|title=Comet 46P/Wirtanen Information|website=theskylive.com|access-date=2017-11-26}}</ref> Since between January 23 and September 26, the comet had an [[Elongation (astronomy)|elongation]] less than 20 degrees from the Sun. |
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The 2018 close approach, combined with Wirtanen's brightness provides an opportunity to study a potential future spacecraft mission target in detail. A worldwide observing campaign<ref>{{Cite web|url=http://wirtanen.astro.umd.edu/|title=The Comet Wirtanen Observing Campaign|website=wirtanen.astro.umd.edu|access-date=2018-06-05}}</ref> was organized to capitalize on the favorable circumstances of the 2018 apparition. |
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On 16 December 2018 the comet will pass {{convert|0.0774|AU|km mi|abbr=on|lk=on}} (≈30.1 [[Lunar distance (astronomy)|LD]]) from Earth,<ref name=jpl-close>{{cite web |
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<gallery mode="packed"> |
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|type=last observation: 2018-11-26; [[Observation arc|arc]]: 202 days |
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File:C46P-sky.png|Path of 46P across the sky during 2018. Its size shown is inversely proportional to its distance. |
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|title=JPL Small-Body Database Browser: 46P/Wirtanen |
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File:C46P-orbit.png|Orbital approach of 46P during 2018, moving south to north and crossing the ecliptic near its closest approach to Earth on December 16, 2018 |
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|url=https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=46P;old=0;orb=1;cov=0;log=0;cad=1#cad |
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File:Comet 46P Wirtanen on 12 December 2018.png|Amateur astronomical image of Comet 46P on 12 December 2018 |
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|accessdate=2018-12-06}}</ref> reaching an estimated magnitude of 4.2,<ref>{{Cite web|url=https://www.timeanddate.com/astronomy/comets/46p-wirtanen-2018.html|title=Look Up! Comet 46P/Wirtanen to Flyby in December 2018|website=timeanddate.com|access-date=2018-12-06}}</ref> making this pass the brightest one predicted, and the brightest close approach for the next 20 years.<ref>{{Cite web|url=https://theskylive.com/46p-info|title=Comet 46P/Wirtanen Information|website=theskylive.com|access-date=2017-11-26}}</ref> Its magnitude could peak as bright as magnitude 3 near its December 16, 2018 closest approach.<ref>http://www.physics-astronomy.org/2018/10/brightest-comet-of-2018-to-light-up-sky.html</ref> |
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File:Comet 46P Wirtanen STSCI-H-p1863.png|View from the [[Hubble Space Telescope]] on December 13, 2018 |
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File:Animation of 46P/Wirtanen orbit.gif|File:Animation of 46P/Wirtanen orbit<br />{{legend2| Yellow| Sun}}{{·}}{{legend2| Lime| Mercury }}{{·}}{{legend2|Cyan|Venus}}{{·}}{{legend2|RoyalBlue|Earth}}{{·}}{{legend2|OrangeRed|Mars}}{{·}}{{legend2|Gold|Jupiter}}{{·}}{{legend2|Magenta|46P/Wirtanen}} |
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The 2018 close approach, combined with Wirtanen's brightness provides an opportunity to study a potential future spacecraft mission target in detail. A worldwide observing campaign<ref>{{Cite web|url=http://wirtanen.astro.umd.edu/|title=The Comet Wirtanen Observing Campaign|website=wirtanen.astro.umd.edu|access-date=2018-06-05}}</ref> has been organized to capitalize on the favorable circumstances of this apparition. |
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<gallery mode=packed> |
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C46P-sky.png|Path of 46P across the sky during 2018. Its size shown is inversely proportional to its distance. |
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C46P-orbit.png|Orbital approach of 46P during 2018, moving south to north and crossing the ecliptic near its closest approach to earth on December 16, 2018 |
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Comet_46P_Wirtanen_on_12_December_2018.png|Amateur astronomical image of Comet 46P on 12 December 2018 |
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</gallery> |
</gallery> |
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[[File:Cometa 46PWirtanen desde Argentina.jpg|thumb|Comet 46P/Wirtanen photographed in the southern hemisphere, from [[Balcarce Partido|Balcarce]], Argentina.]] |
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== Exploration proposals== |
== Exploration proposals== |
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[[File:Picturesque poison 46P Wirtanen.tif|thumb|In December 2018, comet 46P/Wirtanen passed within 11.6 million kilometres of the Earth.<ref>{{cite web |title=Picturesque poison |url=https://www.eso.org/public/images/potw1907a/ |website=www.eso.org |access-date=19 February 2019 |language=en}}</ref>]] |
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[[File:Comet46P AreciboRadar.gif|thumb|[[Radar astronomy|Radar image]] of 46P/Wirtanen imaged by the [[Arecibo Observatory]] in 2018.]] |
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{{main|Comet Hopper}} |
{{main|Comet Hopper}} |
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The comet was the target for the proposed [[Comet Hopper]] mission, which reached the finalist stage in the NASA [[Discovery program]]. It was one of only three missions in that selection to have a more detailed study. The selection process was ultimately won in 2012 by the [[InSight]] mission, a Mars lander. The Comet Hopper was designed to use the ASRG, the [[Advanced Stirling radioisotope generator|Advanced Stirling Radioisotope Generator]]. |
The comet was the target for the proposed [[Comet Hopper]] mission, which reached the finalist stage in the NASA [[Discovery program]]. It was one of only three missions in that selection to have a more detailed study. The selection process was ultimately won in 2012 by the [[InSight]] mission, a Mars lander. The Comet Hopper was designed to use the ASRG, the [[Advanced Stirling radioisotope generator|Advanced Stirling Radioisotope Generator]]. |
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The Comet Hopper mission, if it were selected, would have had multiple science goals over the 7.3 years of its nominal lifetime. At roughly 4.5 [[Astronomical unit|AU]] the spacecraft would rendezvous with Comet Wirtanen and begin to map the spatial heterogeneity of surface solids as well as gas and dust emissions from the [[Coma (cometary)|coma]] - the nebulous envelope around the [[Comet nucleus|nucleus]] of a [[comet]]. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at the comet, the spacecraft would approach and land, then subsequently hop to other locations on the comet. As the comet approached the Sun, the spacecraft would land and hop multiple times.<ref name="BaltSun_MD">{{cite web|title=Maryland scientists vie for NASA missions| |
The Comet Hopper mission, if it were selected, would have had multiple science goals over the 7.3 years of its nominal lifetime. At roughly 4.5 [[Astronomical unit|AU]] the spacecraft would rendezvous with Comet Wirtanen and begin to map the spatial heterogeneity of surface solids as well as gas and dust emissions from the [[Coma (cometary)|coma]] - the nebulous envelope around the [[Comet nucleus|nucleus]] of a [[comet]]. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at the comet, the spacecraft would approach and land, then subsequently hop to other locations on the comet. As the comet approached the Sun, the spacecraft would land and hop multiple times.<ref name="BaltSun_MD">{{cite web|title=Maryland scientists vie for NASA missions|newspaper=[[The Baltimore Sun]]|url=http://articles.baltimoresun.com/2011-05-29/news/bs-md-time-chopper-missions-20110529_1_nasa-missions-nasa-funding-bruce-banerdt/3|access-date=2011-06-02|url-status=dead|archive-url=https://web.archive.org/web/20120926001329/http://articles.baltimoresun.com/2011-05-29/news/bs-md-time-chopper-missions-20110529_1_nasa-missions-nasa-funding-bruce-banerdt/3|archive-date=2012-09-26}}</ref> The final landing would occur at 1.5 AU. As the comet approached the Sun and became more active, the spacecraft would be able to record surface changes.<ref name="AdamsBrief">{{cite web|title=Planetary Science Division Update|publisher=NASA|url=http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|access-date=2011-05-23|archive-url=https://web.archive.org/web/20111114141842/http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|archive-date=2011-11-14|url-status=dead}}</ref> |
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Also, 46P/Wirtanen was the original destination of the [[European Space Agency]]'s [[Rosetta (spacecraft)|Rosetta spacecraft]] mission, but launch delays meant that the comet was no longer easily reachable and another periodic comet, [[67P/Churyumov–Gerasimenko]], was chosen as the mission's target instead.<ref>{{cite web|url = http://sci.esa.int/rosetta/14615-comet-67p/ |title = Comet 67P/Churyumov-Gerasimenko| date = 18 December 2013 | |
Also, 46P/Wirtanen was the original destination of the [[European Space Agency]]'s [[Rosetta (spacecraft)|Rosetta spacecraft]] mission, but launch delays meant that the comet was no longer easily reachable and another periodic comet, [[67P/Churyumov–Gerasimenko]], was chosen as the mission's target instead.<ref>{{cite web|url = http://sci.esa.int/rosetta/14615-comet-67p/ |title = Comet 67P/Churyumov-Gerasimenko| date = 18 December 2013 |access-date = 20 May 2014 |publisher= [[ESA]] |work = Rosetta}}</ref><ref>{{cite press release |
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| date = September 5, 2003 |
| date = September 5, 2003 |
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| title = Hubble Assists Rosetta Comet Mission |
| title = Hubble Assists Rosetta Comet Mission |
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| url = http://hubblesite.org/newscenter/archive/releases/2003/26/text/ |
| url = http://hubblesite.org/newscenter/archive/releases/2003/26/text/ |
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| publisher = [[Hubble Space Telescope]] |
| publisher = [[Hubble Space Telescope]] |
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| |
| access-date = May 20, 2014 |
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}}</ref> |
}}</ref> |
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== Associated |
== Associated meteor showers == |
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Russian forecaster Mikhail Maslov had predicted that the [[Earth's orbit]] would cross Comet Wirtanen's debris stream as many as four times between December 10 and December 14, 2012. As there had not previously been an encounter with this debris stream, it was not certain whether or not a [[meteor shower]] would be visible from Earth, but there was speculation that a shower with as many as 30 meteors per hour might occur.<ref>{{cite web|title=A New Meteor Shower in December?|url=https://science.nasa.gov/science-news/science-at-nasa/2012/11dec_newshower/|publisher=NASA|accessdate=2012-12-13}}</ref> |
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=== 2023 === |
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Observers in Australia reported that on the night of December 14, 2012, as many as a dozen meteors were seen emanating from the predicted radiant in the constellation of [[Pisces (constellation)|Pisces]].<ref>{{cite web|title=Comet Wirtanen meteors report|url=http://www.iceinspace.com.au/forum/showthread.php?p=925959|publisher=IceInSpace|accessdate=2012-12-17}}</ref> |
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Close approaches to Jupiter in 1972 and 1984 moved the comet's orbit closer to Earth, and as of [[Epoch (astronomy)|epoch]] 2018 the comet has an Earth–[[Minimum orbit intersection distance|MOID]] of {{Convert|0.071|AU|e6km e6mi LD|abbr=unit|lk=on}}.<ref name=jpldata/> In 2023 Earth passed through a denser part of the 1974 [[Meteor shower#Origin of meteoroid streams|meteoroid stream]] than Earth did in 2007.<ref name=IMCCE2023/> As a result a shower with [[Radiant (meteor shower)|radiant]] in the southern constellation of [[Sculptor (constellation)|Sculptor]] was observed with a zenithal hourly rate (ZHR) of {{val|0.65|0.24|0.20}} and was given the name ''λ''-Sculptorids. The meteors made [[atmospheric entry]] (Ve) at a relatively slow 15 km/s and as a result the mean mass of the meteoroids observed was about 0.5 grams, about 10 times higher than that of other meteor showers.<ref>{{cite journal |last1=Vida |first1=D. |last2=Scott |first2=J. M. |last3=Egal |first3=A. |last4=Vaubaillon |first4=J. |last5=Ye |first5=Q.-Z. |last6=Rollinson |first6=D. |last7=Sato |first7=M. |last8=Moser |first8=D. E. |title=Observations of the new meteor shower from comet 46P/Wirtanen |journal=Astronomy & Astrophysics |date=February 2024 |volume=682 |pages=L20 |doi=10.1051/0004-6361/202449359|arxiv=2402.07769 }}</ref> |
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{| class="wikitable" style="text-align: center; font-size: 0.9em;" |
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|+Possible meteoroid stream activity<ref name=IMCCE2023/> |
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! Date |
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! [[Meteor shower#Origin of meteoroid streams|Stream]] |
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|- |
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| 2007 || 1974 |
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|- |
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| 2018 || 1980 |
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|- |
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| 2023-December-12 10:54 UT || 1974 |
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|} |
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=== 2012 === |
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Russian forecaster Mikhail Maslov had predicted that the [[Earth's orbit]] would cross Comet Wirtanen's debris stream as many as four times between December 10 and December 14, 2012. As there had not previously been an encounter with this debris stream, it was not certain whether or not a [[meteor shower]] would be visible from Earth, but there was speculation that a shower with as many as 30 meteors per hour might occur.<ref>{{cite web|title=A New Meteor Shower in December?|url=https://science.nasa.gov/science-news/science-at-nasa/2012/11dec_newshower/|publisher=NASA|access-date=2012-12-13 |archive-url=https://web.archive.org/web/20121212184725/https://science.nasa.gov/science-news/science-at-nasa/2012/11dec_newshower/ |archive-date=2012-12-12 |url-status=dead }}</ref> |
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Observers in Australia reported that on the night of December 14, 2012, as many as a dozen meteors were seen emanating from the predicted radiant in the constellation of [[Pisces (constellation)|Pisces]].<ref>{{cite web|title=Comet Wirtanen meteors report|url=http://www.iceinspace.com.au/forum/showthread.php?p=925959|publisher=IceInSpace|access-date=2012-12-17}}</ref> |
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== References == |
== References == |
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{{Reflist |
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{{reflist}} |
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| refs = |
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<ref name=kronk>{{Cite web |
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|first=Gary W. |last=Kronk |
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|author-link=Gary W. Kronk |
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|title=46P/Wirtanen |
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|url=http://cometography.com/pcomets/046p.html |
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|access-date=2019-03-03}} ([http://cometography.com Cometography Home Page])</ref> |
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<ref name=MPC>{{cite web |
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|title=46P/Wirtanen Orbit |
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|url=https://www.minorplanetcenter.net/db_search/show_object?object_id=46P |
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|publisher=[[Minor Planet Center]] |
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|access-date=2023-10-01}}</ref> |
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<ref name="Kinoshita">{{cite web |
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|title=46P/Wirtanen past, present and future orbital elements |
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|url=http://jcometobs.web.fc2.com/pcmtn/0046p.htm |
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|work=Comet Orbit |
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|first=Kazuo |last=Kinoshita |
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|date=2019-06-09 |
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|archive-url=https://web.archive.org/web/20120422080321/http://jcometobs.web.fc2.com/pcmtn/0046p.htm |
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|archive-date=2012-04-22 |
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|url-status=live |
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|access-date=2023-10-01}}</ref> |
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<ref name=jpldata>{{cite web |
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|type=last observation: 2019-07-01; [[Observation arc|arc]]: 1.15 years |
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|title=JPL Small-Body Database: 46P/Wirtanen |
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|url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=46P&view=OPC |
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|archive-url=https://web.archive.org/web/20210723152712/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=46P;orb=1;cad=1 |
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|archive-date=2021-07-23 |
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|url-status=live |
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|access-date=2023-10-01}}</ref> |
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<ref name=JPL-7306>{{cite web |
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|title=See a Passing Comet This Sunday |
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|url=https://www.jpl.nasa.gov/news/news.php?feature=7306 |
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|publisher=JPL |
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|access-date=2019-03-03}}</ref> |
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<ref name=IMCCE2023>{{cite web |
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|title=A new meteor shower caused by comet 46P/Wirtanen |
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|url=https://www.imcce.fr/recherche/campagnes-observations/meteors/2023wir |
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|publisher=IMCCE |
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|access-date=2023-10-01}}</ref> |
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}} <!-- end of reflist--> |
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== External links == |
== External links == |
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{{Comets}} |
{{Comets}} |
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{{2018 in space}} |
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{{PeriodicComets Navigator|45P/Honda–Mrkos–Pajdušáková|47P/Ashbrook–Jackson}} |
{{PeriodicComets Navigator|45P/Honda–Mrkos–Pajdušáková|47P/Ashbrook–Jackson}} |
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{{Authority control}} |
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{{DEFAULTSORT:Wirtanen}} |
{{DEFAULTSORT:Wirtanen}} |
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[[Category: |
[[Category:Periodic comets]] |
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[[Category: |
[[Category:Numbered comets|0046]] |
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[[Category:Near-Earth comets|046P]] |
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[[Category:Discoveries by Carl A. Wirtanen|+]] |
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[[Category:Comets in 2013]] |
[[Category:Comets in 2013]] |
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[[Category:Comets in 2018]] |
[[Category:Comets in 2018]] |
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[[Category: |
[[Category:Astronomical objects discovered in 1948|19480117]] |
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[[Category:Discoveries by Carl A. Wirtanen| ]] |
Discovery | |
---|---|
Discovered by | Carl A. Wirtanen |
Discovery date | January 17, 1948 |
Designations | |
1961 IV; 1960m; 1967 XIV; 1967k; 1974 XI; 1974i; 1986 VI; 1985q; 1991 XVI; 1991s; 46P/1948 A1; 1947 XIII; 1948b; 46P/1954 R2; 1954 XI; 1954j | |
Orbital characteristics[1] | |
Epoch | 2023-02-25 (JDT 2460000.5) |
Aphelion | 5.127 AU |
Perihelion | 1.055 AU |
Semi-major axis | 3.091 AU |
Eccentricity | 0.65867 |
Orbital period | 5.43 yr |
Inclination | 11.749° |
Last perihelion | December 12, 2018[1] July 9, 2013[2] February 2, 2008 |
Next perihelion | 2024-May-19[1] |
Earth MOID | 0.071 AU (10,600,000 km)[3] |
Physical characteristics | |
Dimensions | 1.4 km (radar)[4] |
8.9 hours[4] |
Perihelion distance at different epochs[5] | |||||||
Epoch | Perihelion (AU) | ||||||
---|---|---|---|---|---|---|---|
1967 | 1.61 | ||||||
1974 | 1.26 | ||||||
1986 | 1.08 | ||||||
2013 | 1.05 | ||||||
2035 | 1.08 | ||||||
2046 | 1.22 | ||||||
2059 | 1.98 | ||||||
2095 | 2.01 |
46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years.[6][7] It was the original target for close investigation by the Rosetta spacecraft, planned by the European Space Agency, but an inability to meet the launch window caused Rosetta to be sent to 67P/Churyumov–Gerasimenko instead.[8] It belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Its diameter is estimated at 1.4 kilometres (0.9 mi). In December 2019, astronomers reported capturing an outburst of the comet in substantial detail by the TESS space telescope.[6][7]
46P/Wirtanen was discovered photographically on January 17, 1948, by the American astronomer Carl A. Wirtanen.[9] The plate was exposed on January 15 during a stellar proper motion survey for the Lick Observatory. Due to a limited number of initial observations, it took more than a year to recognize this object as a short-period comet.
The July 2013 perihelion passage was not favorable, only reaching a magnitude of 14.7.[10] Between January 23 and September 26 of 2013, the comet had an elongation less than 20 degrees from the Sun.
On 16 December 2018 the comet passed 0.07746 AU (11.6 million km; 7.20 million mi; 30.1 LD) from Earth,[3] marking one of the 10 closest comet flybys of Earth in 70 years.[11] The comet reached an estimated magnitude of 3.9,[12] making this pass the brightest one predicted, and the brightest close approach for the next 20 years.[10] The comet experienced six outbursts, with the comet brightening by −0.2 to −1.6 magnitudes.[13]
The 2018 close approach, combined with Wirtanen's brightness provides an opportunity to study a potential future spacecraft mission target in detail. A worldwide observing campaign[14] was organized to capitalize on the favorable circumstances of the 2018 apparition.
The comet was the target for the proposed Comet Hopper mission, which reached the finalist stage in the NASA Discovery program. It was one of only three missions in that selection to have a more detailed study. The selection process was ultimately won in 2012 by the InSight mission, a Mars lander. The Comet Hopper was designed to use the ASRG, the Advanced Stirling Radioisotope Generator.
The Comet Hopper mission, if it were selected, would have had multiple science goals over the 7.3 years of its nominal lifetime. At roughly 4.5 AU the spacecraft would rendezvous with Comet Wirtanen and begin to map the spatial heterogeneity of surface solids as well as gas and dust emissions from the coma - the nebulous envelope around the nucleus of a comet. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at the comet, the spacecraft would approach and land, then subsequently hop to other locations on the comet. As the comet approached the Sun, the spacecraft would land and hop multiple times.[16] The final landing would occur at 1.5 AU. As the comet approached the Sun and became more active, the spacecraft would be able to record surface changes.[17]
Also, 46P/Wirtanen was the original destination of the European Space Agency's Rosetta spacecraft mission, but launch delays meant that the comet was no longer easily reachable and another periodic comet, 67P/Churyumov–Gerasimenko, was chosen as the mission's target instead.[18][19]
Close approaches to Jupiter in 1972 and 1984 moved the comet's orbit closer to Earth, and as of epoch 2018 the comet has an Earth–MOID of 0.071 AU (10.6 million km; 6.6 million mi; 28 LD).[3] In 2023 Earth passed through a denser part of the 1974 meteoroid stream than Earth did in 2007.[20] As a result a shower with radiant in the southern constellation of Sculptor was observed with a zenithal hourly rate (ZHR) of 0.65+0.24
−0.20 and was given the name λ-Sculptorids. The meteors made atmospheric entry (Ve) at a relatively slow 15 km/s and as a result the mean mass of the meteoroids observed was about 0.5 grams, about 10 times higher than that of other meteor showers.[21]
Date | Stream |
---|---|
2007 | 1974 |
2018 | 1980 |
2023-December-12 10:54 UT | 1974 |
Russian forecaster Mikhail Maslov had predicted that the Earth's orbit would cross Comet Wirtanen's debris stream as many as four times between December 10 and December 14, 2012. As there had not previously been an encounter with this debris stream, it was not certain whether or not a meteor shower would be visible from Earth, but there was speculation that a shower with as many as 30 meteors per hour might occur.[22]
Observers in Australia reported that on the night of December 14, 2012, as many as a dozen meteors were seen emanating from the predicted radiant in the constellation of Pisces.[23]
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