Editing Habitable zone (section)

===Habitable super-Earths===
{{Category see also|Super-Earths in the habitable zone}}
[[File:Gliese 581 - 2010.jpg|thumb|The habitable zone of Gliese 581 compared with the Solar System's habitable zone]]

The 2007 discovery of [[Gliese 581c]], the first [[super-Earth]] in the circumstellar habitable zone, created significant interest in the system by the scientific community, although the planet was later found to have extreme surface conditions that may resemble Venus.<ref>{{cite news |url=http://www.space.com/scienceastronomy/070424_exoplanet_side.html |title=Planet Hunters Edge Closer to Their Holy Grail |last=Than |first=Ker |date=2007-02-24 |publisher=space.com |access-date=2007-04-29}}</ref> Gliese 581 d, another planet in the same system and thought to be a better candidate for habitability, was also announced in 2007. Its existence was later disconfirmed in 2014, but only for a short time. As of 2015, the planet has no newer disconfirmations. [[Gliese 581 g]], yet another planet thought to have been discovered in the circumstellar habitable zone of the system, was considered to be more habitable than both Gliese 581 c and d. However, its existence was also disconfirmed in 2014,<ref name="SCI-20140703">{{cite journal|last1=Robertson |first1=Paul |author2-link=Suvrath Mahadevan |last2=Mahadevan |first2=Suvrath |last3=Endl |first3=Michael |last4=Roy |first4=Arpita |title=Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581 |journal=[[Science (journal)|Science]] |date=3 July 2014 |doi=10.1126/science.1253253 |pmid=24993348 |arxiv=1407.1049 |bibcode=2014Sci...345..440R |volume=345 |issue=6195 |pages=440–444|citeseerx=10.1.1.767.2071 |s2cid=206556796 }}</ref> and astronomers are divided about its existence.

[[File:Kepler-22 diagram.jpg|thumb|left|A diagram comparing size (artist's impression) and orbital position of planet Kepler-22b within Sun-like star Kepler 22's habitable zone and that of Earth in the Solar System]]

Discovered in August 2011, [[HD 85512 b]] was initially speculated to be habitable,<ref name=maxisciences>{{cite web| url=http://www.maxisciences.com/plan%E8te-habitable/des-chercheurs-decouvrent-une-planete-potentiellement-habitable_art16635.html| title=Researchers find potentially habitable planet| publisher=maxisciences.com| language=fr| access-date=2011-08-31| date=2011-08-30| archive-date=2019-04-13| archive-url=https://web.archive.org/web/20190413203316/https://www.maxisciences.com/planete-habitable/des-chercheurs-decouvrent-une-planete-potentiellement-habitable_art16635.html| url-status=dead}}</ref> but the new circumstellar habitable zone criteria devised by Kopparapu et al. in 2013 place the planet outside the circumstellar habitable zone.<ref name=torres-2013-2 />

[[Kepler-22 b]], discovered in December 2011 by the Kepler space probe,<ref name="bbc20111205">{{cite news| url=https://www.bbc.co.uk/news/science-environment-16040655 |title=Kepler 22-b: Earth-like planet confirmed |publisher=BBC |date=December 5, 2011 |access-date=May 2, 2013}}</ref> is the first [[transit method|transiting]] exoplanet discovered around a [[solar analog|Sun-like star]]. With a radius 2.4 times that of Earth, Kepler-22b has been predicted by some to be an ocean planet.<ref name="Caleb Scharf Blog">{{cite web |url=http://blogs.scientificamerican.com/life-unbounded/2011/12/08/cant-always-tell-an-exoplanet-by-its-size |title=You Can't Always Tell an Exoplanet by Its Size |date=2011-12-08 |last=Scharf |first=Caleb A. |magazine=Scientific American |access-date=2012-09-20 }}: "If it [Kepler-22b] had a similar composition to Earth, then we're looking at a world in excess of about 40 Earth masses".</ref> [[Gliese 667 Cc]], discovered in 2011 but announced in 2012,<ref name=arxiv12020446>{{Cite journal |first1=Guillem |last1=Anglada-Escude |first2=Pamela |last2=Arriagada |first3=Steven |last3=Vogt |first4=Eugenio J. |last4=Rivera |first5=R. Paul |last5=Butler |first6=Jeffrey D. |last6=Crane |first7=Stephen A. |last7=Shectman |first8=Ian B. |last8=Thompson |first9=Dante |last9=Minniti |title=A planetary system around the nearby M dwarf GJ 667C with at least one super-Earth in its habitable zone |date=2012 |arxiv=1202.0446 |doi=10.1088/2041-8205/751/1/L16 |volume=751 |issue=1 |journal=The Astrophysical Journal |page=L16|bibcode = 2012ApJ...751L..16A |s2cid=16531923 }}</ref> is a super-Earth orbiting in the circumstellar habitable zone of [[Gliese 667 C]]. It is one of the most Earth-like planets known.

[[Gliese 163 c]], discovered in September 2012 in orbit around the red dwarf [[Gliese 163]]<ref name="Simbad-20120920">{{cite web |author=<!--Staff writer--> |title=LHS 188 – High proper-motion Star |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HIP+19394 |date=September 20, 2012 |publisher=[[Centre de données astronomiques de Strasbourg]] (Strasbourg astronomical Data Center) |access-date=September 20, 2012 }}</ref> is located 49 [[light year]]s from Earth. The planet has 6.9 Earth masses and 1.8–2.4 Earth radii, and with its close orbit receives 40 percent more stellar radiation than Earth, leading to surface temperatures of about {{formatnum:60}}° [[celsius|C]].<ref name="PHL-20120829">{{cite web |last=Méndez |first=Abel |title=A Hot Potential Habitable Exoplanet around Gliese 163 |url=http://phl.upr.edu/press-releases/ahotpotentialhabitableexoplanetaroundgliese163 |date=August 29, 2012 |publisher=[[University of Puerto Rico at Arecibo]] (Planetary Habitability Laboratory) |access-date=September 20, 2012 |archive-date=October 21, 2019 |archive-url=https://web.archive.org/web/20191021202448/http://phl.upr.edu/press-releases/ahotpotentialhabitableexoplanetaroundgliese163 |url-status=dead }}</ref><ref name="Space-20120920">{{cite web |last=Redd |title=Newfound Alien Planet a Top Contender to Host Life |url=http://www.space.com/17684-alien-planet-gliese-163c-extraterrestrial-life.html |date=September 20, 2012 |publisher=Space.com |access-date=September 20, 2012}}</ref><ref>{{cite web| url=http://www.spacedaily.com/reports/A_Hot_Potential_Habitable_Exoplanet_around_Gliese_163_999.html |title=A Hot Potential Habitable Exoplanet around Gliese 163 |publisher=Spacedaily.com |access-date=2013-02-10}}</ref> [[HD 40307 g]], a candidate planet tentatively discovered in November 2012, is in the circumstellar habitable zone of [[HD 40307]].<ref name="hd40307g_tuomi12">{{cite journal |doi=10.1051/0004-6361/201220268 |last1=Tuomi |first1=Mikko |last2=Anglada-Escudé |first2=Guillem |last3=Gerlach |first3=Enrico |last4=Jones |first4=Hugh R. A. |last5=Reiners |first5=Ansgar |last6=Rivera |first6=Eugenio J. |last7=Vogt |first7=Steven S. |last8=Butler |first8=R. Paul |title=Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307 |journal=Astronomy & Astrophysics |date=17 December 2012 |volume=549 |pages=A48 |arxiv=1211.1617 |bibcode=2013A&A...549A..48T |s2cid=7424216 }}</ref> In December 2012, [[Tau Ceti e]] and [[Tau Ceti f]] were found in the circumstellar habitable zone of [[Tau Ceti]], a Sun-like star 12 light years away.<ref name=aron-2012>{{cite web |url=https://www.newscientist.com/article/dn23021-nearby-tau-ceti-may-host-two-planets-suited-to-life.html |title=Nearby Tau Ceti may host two planets suited to life |publisher=Reed Business Information |work=New Scientist |date=December 19, 2012 |access-date=April 1, 2013 |author=Aron, Jacob}}</ref> Although more massive than Earth, they are among the least massive planets found to date orbiting in the habitable zone;<ref name="tuomi-2013">{{Cite journal | last1 = Tuomi | first1 = M. | last2 = Jones | first2 = H. R. A. | last3 = Jenkins | first3 = J. S. | last4 = Tinney | first4 = C. G. | last5 = Butler | first5 = R. P. | last6 = Vogt | first6 = S. S. | last7 = Barnes | first7 = J. R. | last8 = Wittenmyer | first8 = R. A. | last9 = o'Toole | first9 = S. | last10 = Horner | first10 = J. | last11 = Bailey | first11 = J. | last12 = Carter | first12 = B. D. | last13 = Wright | first13 = D. J. | last14 = Salter | first14 = G. S. | last15 = Pinfield | first15 = D. | title = Signals embedded in the radial velocity noise | doi = 10.1051/0004-6361/201220509 | journal = Astronomy & Astrophysics | volume = 551 | pages = A79 | year = 2013 |arxiv = 1212.4277 |bibcode = 2013A&A...551A..79T | s2cid = 2390534 }}</ref> however, Tau Ceti f, like HD 85512 b, did not fit the new circumstellar habitable zone criteria established by the 2013 Kopparapu study.<ref name=mendes-2013-3>{{cite web |url=http://phl.upr.edu/projects/habitable-exoplanets-catalog |title=The Habitable Exoplanets Catalog |publisher=University of Puerto Rico |date=May 1, 2013 |access-date=May 1, 2013 |author=Torres, Abel Mendez}}</ref> It is now considered as uninhabitable.