Editing Polaris

{{short description|Brightest star in the constellation Ursa Minor}}
{{about|the Earth's current north star|such stars in general|pole star||Polaris (disambiguation)|and|North Star (disambiguation)}}
{{redirect|Stella Polaris|the military operation|Operation Stella Polaris}}
{{starbox begin
|name=Polaris
}}
{{Starbox image
 | image=
   {{Location mark
     | image=Ursa Minor constellation map.svg
     | float=center | width=250 | position=right
     | mark=Red circle.svg | mark_width=12 | mark_link=Polaris (star)
     | x%=49.5 | y%=4.5
   }}
 | caption=Location of Polaris (circled)
}}
{{Starbox observe 2s
| epoch = J2000
| equinox = <!--Equinox of coordinates (defaults to epoch)-->
| pronounce = {{IPAc-en|p|ə|'|l|ɛər|ɪ|s|,_|-|ˈ|l|æ|r|-}};<br/>{{IPAc-en|UK|p|ə|'|l|ɑːr|ɪ|s}}<ref>{{cite web |title=Polaris {{pipe}} meaning in the Cambridge English Dictionary |website=[[Cambridge English Dictionary]] |url=https://dictionary.cambridge.org/dictionary/english/polaris |access-date=11 December 2020}}</ref>
| constell = [[Ursa Minor]]
| component1 = α UMi A
| ra1 = {{RA|02|31|49.09}}<ref name=hipparcos2/>
| dec1 = {{DEC|+89|15|50.8}}<ref name=hipparcos2/>
| appmag_v1 = 1.98<ref name=hst>{{Cite journal |last1 = Evans |first1 = N. R. |last2 = Schaefer |first2 = G. H. |last3 = Bond |first3 = H. E. |last4 = Bono |first4 = G. |last5 = Karovska |first5 = M. |last6 = Nelan |first6 = E. |last7 = Sasselov |first7 = D. |last8 = Mason |first8 = B. D. |doi = 10.1088/0004-6256/136/3/1137 |title = Direct Detection of the Close Companion of Polaris with The Hubble Space Telescope |journal = The Astronomical Journal |volume = 136 |issue = 3 |pages = 1137 |year = 2008 |arxiv = 0806.4904 |bibcode = 2008AJ....136.1137E |s2cid = 16966094 }}</ref> (1.86{{snd}}2.13)<ref name=gcvs/>
| component2 = α UMi B
| ra2 = {{RA|02|30|41.63}}<ref name="Gaia_DR3"/>
| dec2 = {{DEC|+89|15|38.1}}<ref name="Gaia_DR3"/>
| appmag_v2 = 8.7<ref name=hst/>
}}
{{Starbox character
| component = α UMi A
| type = <!--Type of star (e.g., main sequence star, protostar, white dwarf, neutron star, etc.)-->
| class = F7Ib + F6V<ref name=lee/>
| r-i = <!--R−I color-->
| v-r = <!--V−R color-->
| b-v = 0.60<ref name=hst/>
| u-b = 0.38<ref name=hst/>
| j-h = <!--J−H color-->
| j-k = <!--J−K color-->
| variable = [[Classical Cepheid]]<ref name=gcvs>{{cite journal | last1=Samus | first1=N. N. | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V. | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N. | display-authors=2 | title=General Catalogue of Variable Stars | version=5.1 | journal=Astronomy Reports | date=2017 | volume=61 | issue=1 | pages=80–88 | doi=10.1134/S1063772917010085 | bibcode=2017ARep...61...80S | s2cid=125853869 }}</ref>
| component2 = α UMi B
| type2 = <!--Type of star (e.g., main sequence star, protostar, white dwarf, neutron star, etc.)-->
| class2 = F3V<ref name=hst/>
| r-i2 = <!--R−I color-->
| v-r2 = <!--V−R color-->
| b-v2 = 0.42<ref name=usenko/>
| u-b2 = 0.01<ref name=usenko/>
| j-h2 = <!--J−H color-->
| j-k2 = <!--J−K color-->
| variable2 = suspected<ref name=gcvs/>
}}
{{Starbox astrometry
 | radial_v = −17<ref>{{Cite journal |last=Campbell |first=William Wallace |title=The radial velocities of 915 stars |journal=Lick Observatory Bulletin|year=1913 |volume=229 |page=113 |doi=10.5479/ADS/bib/1913LicOB.7.113C |bibcode=1913LicOB...7..113C }}</ref>
 | prop_mo_ra = {{val|198.8|0.20}}<ref name=hipparcos2/>
 | prop_mo_dec = {{val|-15|0.30}}<ref name=hipparcos2/>
 | parallax = 7.54
 | p_error = 0.11
 | parallax_footnote = <ref name=hipparcos2/>
 | dist_ly = {{val|{{convert|136.9|pc|ly|sigfig=4|disp=number}}|{{convert|0.34|pc|ly|sigfig=2|disp=number}}}}
 | dist_pc = {{val|136.90|0.34}}
 | dist_footnote = <ref name=evans2024/>
 | absmag_v = −3.6 (''α UMi Aa'')<ref name=hst/><br/>3.6 (''α UMi Ab'')<ref name=hst/><br/>3.1 (''α UMi B'')<ref name=hst/>
}}
{{Starbox relpos
| reference = <!-- Grand reference -->
| epoch = 2005.5880
| primary = α UMi Aa
| component = α UMi Ab
| angdistsec = 0.172
| angdistmas = <!--Angular distance, in milliarcseconds (alternatively, use angdistsec) -->
| angdistref = <!--Reference for angular distance -->
| posang = 231.4
| posangref = <!--Reference for position angle -->
| projsep = <!--Observed projected separation, in AU -->
| projsepref = <!--Reference for projected separation -->
}}
{{Starbox relpos
| reference = <!-- Grand reference -->
| epoch = 2005.5880
| primary = α UMi Aa
| component = α UMi B
| angdistsec = 18.217
| angdistmas = <!--Angular distance, in milliarcseconds (alternatively, use angdistsec) -->
| angdistref = <!--Reference for angular distance -->
| posang = 230.540
| posangref = <!--Reference for position angle -->
| projsep = <!--Observed projected separation, in AU -->
| projsepref = <!--Reference for projected separation -->
}}
{{Starbox orbit
| reference = <ref name=evans2024/>
| primary = α UMi Aa
| name = α UMi Ab
| period = {{val|29.416|0.028}}
| axis = {{val|0.12955|0.00205}}
| axis_unitless = {{val|2.90|0.03|p=≥|ul=AU}}<ref name=Anderson2019/>
| eccentricity = {{val|0.6354|0.0066}}
| inclination = {{val|127.57|1.22}}
| node = {{val|201.28|1.18}}
| periastron = {{val|2016.831|0.044}}
| periarg_primary = {{val|304.54|0.84}}
| k1 = {{val|3.762|0.025}}
| k2 = <!-- Velocity semi-amplitude (secondary in SB2), in km/s -->
}}
<!-- note, I have only included the Aa/Ab orbital information above. The A/B orbital information is below, should someone decide to either update the functionality of starbox orbit or add another instance of it.
| primsec_2 = B/A
| period_unitless_2 = ~100,000 years
| axis_unitless_2 = 32" (0.02 pc)
-->
{{Starbox detail
| component1              = α UMi Aa
| source                 =   <!--[source url]-->
| mass                   = {{val|5.13|0.28}}<ref name=evans2024/>
| radius                 =   {{val|46.27|0.42}}<ref name=evans2024/>
| luminosity_bolometric  =   1,260<ref name=fadeyev>{{cite journal |bibcode=2015MNRAS.449.1011F |arxiv=1502.06463 |doi = 10.1093/mnras/stv412 |title=Evolutionary status of Polaris|journal=Monthly Notices of the Royal Astronomical Society |volume=449 |issue=1 |pages=1011–1017 |year=2015 |last1=Fadeyev |first1=Y. A. |doi-access=free |s2cid=118517157}}</ref>
| gravity                =   2.2<ref name=usenko2005>{{Cite journal |last1 = Usenko |first1 = I. A. |last2 = Miroshnichenko |first2 = A. S. |last3 = Klochkova |first3 = V. G. |last4 = Yushkin |first4 = M. V. |title = Polaris, the nearest Cepheid in the Galaxy: Atmosphere parameters, reddening and chemical composition |doi = 10.1111/j.1365-2966.2005.09353.x |journal = Monthly Notices of the Royal Astronomical Society |volume = 362 |issue = 4 |pages = 1219 |year = 2005 |bibcode = 2005MNRAS.362.1219U |doi-access = free}}</ref>
| temperature            =   6015<ref name=usenko/>
| metal                  =   112% solar<ref name=strobel>{{Cite journal | last1 = Cayrel de Strobel | first1 = G. | last2 = Soubiran | first2 = C. | last3 = Ralite | first3 = N. | year = 2001 | title = Catalogue of [Fe/H] determinations for FGK stars: 2001 edition | journal = Astronomy and Astrophysics | volume = 373 | pages = 159–163 | arxiv = astro-ph/0106438| bibcode = 2001A&A...373..159C| doi = 10.1051/0004-6361:20010525 | s2cid = 17519049 }}</ref>
| rotation               =   119 days<ref name=lee>{{Cite journal | last1 = Lee | first1 = B. C. | last2 = Mkrtichian | first2 = D. E. | last3 = Han | first3 = I. | last4 = Park | first4 = M. G. | last5 = Kim | first5 = K. M. | title = Precise Radial Velocities of Polaris: Detection of Amplitude Growth | doi = 10.1088/0004-6256/135/6/2240 | journal = The Astronomical Journal | volume = 135 | issue = 6 | pages = 2240 | year = 2008 |arxiv = 0804.2793 |bibcode = 2008AJ....135.2240L | s2cid = 12176373 }}</ref>
| rotational_velocity    =   14<ref name=lee/>
| age_myr                =   45 - 67<ref name=neilson2021>{{cite conference |bibcode=2021ASPC..529...72N |title=The Curious Case of the North Star: The Continuing Tension Between Evolution Models and Measurements of Polaris |last1=Neilson |first1=H. R. |last2=Blinn |first2=H. |conference=RR Lyrae/Cepheid 2019: Frontiers of Classical Pulsators |date=2021 |volume=529 |page=72 |arxiv=2003.02326 }}</ref>
}}
{{Starbox detail|no_heading=y
| source                 =   <!--[source url]-->
| component1             =   α UMi Ab
| mass                   =   1.316<ref name=evans2024/>
| radius                 =   1.04<ref name=hst/>
| luminosity_bolometric  =   3<ref name=hst/>
| age_myr                =   >500<ref name=neilson2021/>
| component2             =   α UMi B
| mass2                  =   1.39<ref name=hst/>
| radius2                =   1.38<ref name=usenko/>
| luminosity_bolometric2 =   3.9<ref name=usenko>{{Cite journal | last1 = Usenko | first1 = I. A. | last2 = Klochkova | first2 = V. G. | doi = 10.1111/j.1745-3933.2008.00426.x | title = Polaris B, an optical companion of the Polaris (α UMi) system: Atmospheric parameters, chemical composition, distance and mass | journal = Monthly Notices of the Royal Astronomical Society: Letters | volume = 387 | issue = 1 | pages = L1 | year = 2008 | doi-access = free |arxiv = 0708.0333 |bibcode = 2008MNRAS.387L...1U | s2cid = 18848139 }}</ref>
| gravity2               =   4.3<ref name=usenko/>
| temperature2           =   6900<ref name=usenko/>
| rotational_velocity2   =   110<ref name=usenko/>
| age_gyr2               =   1.5<ref name=neilson2021/>
}}
{{Starbox catalog
| names = {{odlist | name=Polaris, North Star, Cynosura | B=Alpha UMi, α UMi | ADS=1477 | CCDM=J02319+8915 }}
| component2 = α UMi A
| names2 = {{odlist | F=1 Ursae Minoris | HR=424 | BD=+88°8 | HD=8890 | SAO=308 | FK5=907 | GC=2243 | HIP=11767 }}
| component3 = α UMi B
| names3 = {{odlist | BD=+88°7 | SAO=305 | GC=2226 | NSV=631 }}
}}
{{Starbox reference
| Simbad = Polaris|sn=α UMi A
| Simbad2 = Polaris+B|sn2=α UMi B
}}
{{starbox end}}

'''Polaris''' is a [[star]] in the northern [[circumpolar constellation]] of [[Ursa Minor]]. It is designated '''α Ursae Minoris''' ([[Latinisation of names|Latinized]] to ''Alpha Ursae Minoris'') and is commonly called the '''North Star''' or '''Pole Star'''. With an [[apparent magnitude]] that fluctuates around 1.98,<ref name=hst/> it is the brightest star in the constellation and is readily visible to the [[naked eye]] at night.<ref name=Kaler>{{cite web |url=http://stars.astro.illinois.edu/sow/polaris.html |title=Polaris (Alpha Ursae Minoris) |first=Jim |last=Kaler |author-link=James B. Kaler |website=Stars |access-date=2020-09-09}}</ref> The position of the star lies less than [[angular distance|1°]] away from the north [[celestial pole]], making it the current northern [[pole star]]. The stable position of the star in the [[northern celestial hemisphere|Northern Sky]] makes it useful for [[celestial navigation|navigation]].<ref name="s936">{{cite web | last=McNamee | first=Gregory | title=How the stars, planets and other celestial objects got their names | website=CNN | date=2021-05-26 | url=https://edition.cnn.com/2021/05/25/world/how-stars-planets-constellations-comets-named-scn/index.html | access-date=2024-08-28}}</ref>

As the closest [[Cepheid variable]] its distance is used as part of the [[cosmic distance ladder]]. The revised ''[[Hipparcos]]'' [[stellar parallax]] gives a distance to Polaris of about {{convert|433|ly|pc|abbr=off|lk=on}}, while the successor mission [[Gaia (spacecraft)|''Gaia'']] gives a distance of about {{convert|448|ly|pc|abbr=off|lk=on}}.

Although appearing to the naked eye as a single point of light, Polaris is a triple [[star system]], composed of the primary, a [[yellow supergiant]] designated Polaris Aa, in orbit with a smaller companion, Polaris Ab; the pair is in a wider orbit with Polaris B. The outer pair AB were discovered in August 1779 by [[William Herschel]], where the 'A' refers to what is now known to be the Aa/Ab pair.

==Stellar system==
[[File:Polaris alpha ursae minoris.jpg|thumb|left|upright=1.2|Polaris components as seen by the [[Hubble Space Telescope]]]]
Polaris Aa is an [[stellar evolution|evolved]] [[yellow supergiant]] of [[stellar classification|spectral type]] F7Ib with 5.4 [[solar mass]]es ({{Solar mass|link=y}}). It is the first classical [[Cepheid]] to have a mass determined from its orbit. The two smaller companions are Polaris B, a {{Solar mass|1.39}} F3 [[main sequence|main-sequence]] star orbiting at a distance of {{val|2400|ul=astronomical units|fmt=commas}} (AU),<ref name=Wielen>{{cite journal|bibcode=2000A&A...360..399W|arxiv = astro-ph/0002406 |title = Polaris: Astrometric orbit, position, and proper motion |journal = Astronomy and Astrophysics |volume = 360 |pages = 399–410 [400–402, 406] |last1 = Wielen |first1 = R. |last2 = Jahreiß |first2 = H. |last3 = Dettbarn |first3 = C. |last4 = Lenhardt |first4 = H. |last5 = Schwan |first5 = H. |year = 2000 }}</ref> and Polaris Ab (or P), a very close F6 main-sequence star with a mass of {{Solar mass|1.26}}.<ref name=hst/> Polaris B can be resolved with a modest telescope. William Herschel discovered the star in August 1779 using a [[reflecting telescope]] of his own,<ref>{{cite book
 | title=An Anthology of Visual Double Stars
 | display-authors=1 | first1=Bob | last1=Argyle
 | first2=Mike | last2=Swan | first3=Andrew | last3=James
 | date=August 29, 2019 | page=265 | isbn=9781108601702 
 | publisher=Cambridge University Press
 | url=https://books.google.com/books?id=jSmqDwAAQBAJ&pg=PT265
}}</ref> one of the best telescopes of the time. In January 2006, [[NASA]] released images, from the [[Hubble Space Telescope|Hubble telescope]], that showed the three members of the Polaris ternary system.<ref>{{cite web|url=https://hubblesite.org/contents/news-releases/2006/news-2006-02.html |title=There's More to the North Star Than Meets the Eye |publisher=Hubblesite.org |date=2006-01-09 |access-date=2020-02-27}}</ref><ref name=evans/>

The variable [[radial velocity]] of Polaris A was reported by [[William Wallace Campbell|W. W. Campbell]] in 1899, which suggested this star is a binary system.<ref>{{cite journal
 | title=On the variable velocity of Polaris in the line of sight
 | last=Campbell | first=W. W.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=11 | pages=195–199| date=October 1899
 | doi=10.1086/121339 | bibcode=1899PASP...11..195C
| s2cid=122429136 }}</ref> Since Polaris A is a known cepheid variable, [[Joseph Haines Moore|J. H. Moore]] in 1927 demonstrated that the changes in velocity along the line of sight were due to a combination of the four-day [[stellar pulsation|pulsation]] period combined with a much longer [[orbital period]] and a large [[orbital eccentricity|eccentricity]] of around 0.6.<ref>{{cite journal
 | title=Note on the Longitude of the Lick Observatory
 | last=Moore | first=J. H.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=39 | issue=230 | page=249 | date=August 1927
 | doi=10.1086/123734 | bibcode=1927PASP...39..249M
| s2cid=119469812 | doi-access=free }}</ref> Moore published preliminary [[orbital elements]] of the system in 1929, giving an [[orbital period]] of about 29.7 years with an eccentricity of 0.63. This period was confirmed by [[proper motion]] studies performed by [[Boris Gerasimovich|B. P. Gerasimovič]] in 1939.<ref name=Roemer1965>{{cite journal
 | title=Orbital Motion of Alpha Ursae Minoris from Radial Velocities
 | last=Roemer | first=Elizabeth
 | journal=Astrophysical Journal
 | volume=141 | page=1415 | date=May 1965
 | doi=10.1086/148230 | bibcode=1965ApJ...141.1415R
| doi-access=free}}</ref>

As part of her doctoral thesis, in 1955 [[Elizabeth Roemer|E. Roemer]] used radial velocity data to derive an orbital period of 30.46&nbsp;y for the Polaris A system, with an eccentricity of 0.64.<ref>{{cite journal
 | title=Parallax and orbital motion of spectroscopic binary Polaris from photographs taken with the 24-inch Sproul refractor.
 | last=Wyller | first=A. A.
 | journal=Astronomical Journal
 | volume=62 | pages=389–393 | date=December 1957
 | doi=10.1086/107559 | bibcode=1957AJ.....62..389W }}</ref> [[Karl Walter Kamper|K. W. Kamper]] in 1996 produced refined elements with a period of {{val|29.59|0.02|u=years}} and an eccentricity of {{val|0.608|0.005}}.<ref name=Kamper1996>{{cite journal
 | title=Polaris Today
 | last=Kamper | first=Karl W.
 | journal=Journal of the Royal Astronomical Society of Canada
 | volume=90 | page=140 | date=June 1996
 | bibcode=1996JRASC..90..140K }}</ref> In 2019, a study by R. I. Anderson gave a period of {{val|29.32|0.11|u=years}} with an eccentricity of {{val|0.620|0.008}}.<ref name=Anderson2019>{{cite journal
 | title=Probing Polaris' puzzling radial velocity signals. Pulsational (in-)stability, orbital motion, and bisector variations
 | last=Anderson | first=R. I.
 | journal=Astronomy & Astrophysics
 | volume=623 | id=A146 | pages=17 | date=March 2019
 | doi=10.1051/0004-6361/201834703 | arxiv=1902.08031
 | bibcode=2019A&A...623A.146A | s2cid=119467242 }}</ref>

There were once thought to be two more widely separated components—Polaris C and Polaris D—but these have been shown not to be physically associated with the Polaris system.<ref name=Wielen/><ref>{{cite journal|bibcode=2010AJ....139.1968E|title=Chandra Observation of Polaris: Census of Low-mass Companions|journal=The Astronomical Journal|volume=139|issue=5|pages=1968|last1=Evans|first1=Nancy Remage|last2=Guinan|first2=Edward|last3=Engle|first3=Scott|last4=Wolk|first4=Scott J.|last5=Schlegel|first5=Eric|last6=Mason|first6=Brian D.|last7=Karovska|first7=Margarita|last8=Spitzbart|first8=Bradley|year=2010|doi=10.1088/0004-6256/139/5/1968|doi-access=free}}</ref>

== Observation ==

===Variability===
[[File:AlphaUMiLightCurve.png|thumb|left|A [[light curve]] for Polaris, plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data<ref name=MAST>{{cite web |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>]]
Polaris Aa, the supergiant primary component, is a low-amplitude [[Population I]] [[classical Cepheid variable]], although it was once thought to be a [[type II Cepheid]] due to its high [[galactic latitude]]. Cepheids constitute an important [[standard candle]] for determining distance, so Polaris, as the closest such star,<ref name=Anderson2019/> is heavily studied. The [[Variable star|variability]] of Polaris had been suspected since 1852; this variation was confirmed by [[Ejnar Hertzsprung]] in 1911.<ref>{{cite journal
 | last1=Hertzsprung | first1=Ejnar
 | title=Nachweis der Veränderlichkeit von α Ursae Minoris
 | journal=Astronomische Nachrichten | volume=189 | page=89
 | date=August 1911 | language=de
 | doi=10.1002/asna.19111890602 | bibcode=1911AN....189...89H
 | issue=6 | url=https://zenodo.org/record/1424878
 }}</ref>

The range of brightness of Polaris is given as 1.86–2.13,<ref name=gcvs/> but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was very gradually decreasing. After 1966, it very rapidly decreased until it was less than 0.05 magnitude; since then, it has erratically varied near that range. It has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid.<ref name=lee/>

[[File:Integrated Flux Nebula Surrounding Polaris - Kush Chandaria.jpg|thumb|left|Polaris and its surrounding [[Integrated Flux Nebula|integrated flux nebula]]]]
The period, roughly 4 days, has also changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965. This was originally thought to be due to secular redward (a long term change in [[redshift]] that causes light to stretch into longer wavelengths, causing it to appear red) evolution across the Cepheid [[instability strip]], but it may be due to interference between the primary and the first-[[overtone]] pulsation modes.<ref name=evans>{{Cite journal | last1 = Evans | first1 = N. R. | last2 = Sasselov | first2 = D. D. | last3 = Short | first3 = C. I. | doi = 10.1086/338583 | title = Polaris: Amplitude, Period Change, and Companions | journal = The Astrophysical Journal | volume = 567 | issue = 2 | pages = 1121 | year = 2002 |bibcode = 2002ApJ...567.1121E | doi-access = free }}</ref><ref name=turner>{{Cite journal | last1 = Turner | first1 = D. G. | last2 = Savoy | first2 = J. | last3 = Derrah | first3 = J. | last4 = Abdel-Sabour Abdel-Latif | first4 = M. | last5 = Berdnikov | first5 = L. N. | title = The Period Changes of Polaris | doi = 10.1086/427838 | journal = Publications of the Astronomical Society of the Pacific | volume = 117 | issue = 828 | pages = 207 | year = 2005 |bibcode = 2005PASP..117..207T | doi-access = free }}</ref><ref name=neilson>{{Cite journal | last1 = Neilson | first1 = H. R. | last2 = Engle | first2 = S. G. | last3 = Guinan | first3 = E. | last4 = Langer | first4 = N. | last5 = Wasatonic | first5 = R. P. | last6 = Williams | first6 = D. B. | doi = 10.1088/2041-8205/745/2/L32 | title = The Period Change of the Cepheid Polaris Suggests Enhanced Mass Loss | journal = The Astrophysical Journal | volume = 745 | issue = 2 | pages = L32 | year = 2012 |arxiv = 1201.0761 |bibcode = 2012ApJ...745L..32N | s2cid = 118625176 }}</ref> Authors disagree on whether Polaris is a fundamental or first-overtone pulsator and on whether it is crossing the instability strip for the first time or not.<ref name=fadeyev/><ref name=neilson/><ref name=engle>{{cite journal|doi=10.3847/2515-5172/aad2d0|title=Toward Ending the Polaris Parallax Debate: A Precise Distance to Our Nearest Cepheid from Gaia DR2|journal=Research Notes of the AAS|volume=2|issue=3|pages=126|year=2018|last1=Engle|first1=Scott G|last2=Guinan|first2=Edward F|last3=Harmanec|first3=Petr|bibcode=2018RNAAS...2..126E|s2cid=126329676 |doi-access=free }}</ref>

The temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of temperature changes during each cycle, from less than 50&nbsp;[[kelvin|K]] to at least 170&nbsp;K, may be related to the orbit with Polaris Ab.<ref name=usenko2005/>

Research reported in ''[[Science (journal)|Science]]'' suggests that Polaris is 2.5 times brighter today than when [[Ptolemy]] observed it, changing from third to second magnitude.<ref>{{cite journal|doi=10.1126/science.304.5678.1740b|pmid=15205508|year=2004|last1=Irion|first1=R|title=American Astronomical Society meeting. As inconstant as the Northern Star|journal=Science|volume=304|issue=5678|pages=1740–1|s2cid=129246155}}</ref> Astronomer [[Edward Guinan]] considers this to be a remarkable change and is on record as saying that "if they are real, these changes are 100 times larger than [those] predicted by current theories of [[Stellar Evolution|stellar evolution]]".

In 2024, researchers led by Nancy Evans at the [[Harvard–Smithsonian Center for Astrophysics|Harvard & Smithsonian]], have studied with more accuracy the Polaris' smaller companion orbit using the [[CHARA Array]]. During this observation campaign they have succeeded in shooting Polaris features on its surface; large bright places and dark ones have appeared in close-up images, changing over time. Further, Polaris diameter size has been re-measured to {{solar radius|46}}, using the ''Gaia'' distance of {{val|446|1}} light-years, and its mass was determined at {{solar mass|5.13}}.<ref name=evans2024>{{Cite journal |last1=Evans |first1=Nancy Remage |last2=Schaefer |first2=Gail H. |last3=Gallenne |first3=Alexandre |last4=Torres |first4=Guillermo |last5=Horch |first5=Elliott P. |last6=Anderson |first6=Richard I. |last7=Monnier |first7=John D. |last8=Roettenbacher |first8=Rachael M. |last9=Baron |first9=Fabien |last10=Anugu |first10=Narsireddy |last11=Davidson |first11=James W. |last12=Kervella |first12=Pierre |last13=Bras |first13=Garance |last14=Proffitt |first14=Charles |last15=Mérand |first15=Antoine |date=2024-08-01 |title=The Orbit and Dynamical Mass of Polaris: Observations with the CHARA Array |bibcode=2024ApJ...971..190E |journal=The Astrophysical Journal |volume=971 |issue=2 |pages=190 |doi=10.3847/1538-4357/ad5e7a |doi-access=free |arxiv=2407.09641 |issn=0004-637X}}</ref>

===Role as pole star===
{{main|Pole star}}
[[File:Polaris-clock face.jpg|thumb|left|Polaris azimuths vis clock face analogy.<ref name="kaizad_co_uk">{{cite web | url=http://www.kaizad.co.uk/data/Nav/Polaris.xls | title=A visual method to correct a ship's compass using Polaris using Ursa Major as a point of reference | access-date=2016-08-07 | archive-date=2010-08-27 | archive-url=https://web.archive.org/web/20100827042213/http://www.kaizad.co.uk/data/Nav/Polaris.xls | url-status=dead }}</ref>]]
[[File:Star Trail above Beccles - geograph.org.uk - 1855505.jpg|thumb|A typical Northern Hemisphere [[star trail]] with Polaris in the center.]]
[[File:Dipper polaris cass.png|thumb|Polaris lying halfway between the [[Asterism (astronomy)|asterisms]] [[Cassiopeia (constellation)|Cassiopeia]] and the [[Big Dipper]].]]
Because Polaris lies nearly in a direct line with the [[Earth's rotation]]al axis above the [[North Pole]], it stands almost motionless in the sky, and all the stars of the northern sky appear to rotate around it. It thus provides a nearly fixed point from which to draw measurements for [[celestial navigation]] and for [[astrometry]]. The elevation of the star above the horizon gives the approximate [[latitude]] of the observer.<ref name=Kaler/>

In 2018 Polaris was 0.66° (39.6 arcminutes) away from the pole of rotation (1.4 times the [[Moon]] disc) and so revolves around the pole in a small circle 1.3° in diameter. It will be closest to the pole (about 0.45 degree, or 27 arcminutes) soon after the year 2100.<ref>{{cite journal |bibcode=1990JBAA..100..212M |title=Polaris and the North Pole |last1=Meeus |first1=J. |journal=Journal of the British Astronomical Association |year=1990 |volume=100 |page=212 }}</ref> Because it is so close to the celestial north pole, its [[right ascension]] is changing rapidly due to the [[Axial precession|precession of Earth's axis]], going from 2.5h in AD 2000 to 6h in AD 2100. Twice in each [[sidereal day]] Polaris's [[azimuth]] is true north; the rest of the time it is displaced eastward or westward, and the bearing must be corrected using tables or a [[rule of thumb]]. The best approximation<ref name="kaizad_co_uk" /> is made using the leading edge of the "[[Big Dipper]]" [[Asterism (astronomy)|asterism]] in the constellation Ursa Major. The leading edge (defined by the stars [[Alpha Ursae Majoris|Dubhe]] and [[Beta Ursae Majoris|Merak]]) is referenced to a clock face, and the true azimuth of Polaris worked out for different latitudes.

The apparent motion of Polaris towards and, in the future, away from the celestial pole, is due to the [[precession of the equinoxes]].<ref name="Nor">{{cite book | title=Norton's Star Atlas | date=2004 | publisher=Pearson Education | isbn=978-0-13-145164-3 | editor-last=Ridpath | editor-first=Ian | location=New York | page=[https://archive.org/details/nortonsstaratlas00ianr/page/5 5] | quote=Around 4800 years ago Thuban ({{GreekFont|α}} Draconis) lay a mere 0°.1 from the pole. Deneb ({{GreekFont|α}} Cygni) will be the brightest star near the pole in about 8000 years' time, at a distance of 7°.5. | url-access=registration | url=https://archive.org/details/nortonsstaratlas00ianr/page/5 }}</ref> The celestial pole will move away from α UMi after the 21st century, passing close by [[Gamma Cephei]] by about the [[5th millennium#Astronomical events|41st century]], moving towards [[Deneb]] by about the [[10th millennium#Astronomical events|91st century]].{{fact|date=January 2025}}

The celestial pole was close to [[Thuban]] around 2750 BCE,<ref name="Nor" /> and during [[classical antiquity]] it was slightly closer to [[Beta Ursae Minoris|Kochab]] (β UMi) than to Polaris, although still about {{val|10|ul=°}} from either star.<ref>{{cite web | first=Ian | last=Ridpath | url=http://www.ianridpath.com/startales/ursaminor.html#polaris | work=Star Tales | title=Ursa Minor, the Little Bear | date=2018 | access-date=20 August 2016 }}</ref> It was about the same angular distance from β UMi as to α UMi by the end of [[late antiquity]]. The Greek navigator [[Pytheas]] in ca. 320 BC described the celestial pole as devoid of stars. However, as one of the brighter stars close to the celestial pole, Polaris was used for navigation at least from late antiquity, and described as ἀεί φανής (''aei phanēs'') "always visible" by [[Stobaeus]] (5th century), also termed Λύχνος (''Lychnos'') akin to a burner or lamp and would reasonably be described as ''stella polaris'' from about the [[High Middle Ages]] and onwards, both in Greek and Latin. On his first trans-Atlantic voyage in 1492, [[Christopher Columbus]] had to correct for the "circle described by the pole star about the pole".<ref>{{cite book | title=The Life of the Admiral Christopher Columbus by His Son Fredinand | first=Ferdinand | last=Columbus | author-link=Ferdinand Columbus |translator-link=Benjamin Keen | translator1-first=Benjamin | translator1-last=Keen | publication-place=London | publisher=Folio Society | date=1960 | page=74 }}</ref> In [[William Shakespeare|Shakespeare's]] play [[Julius Caesar (play)|Julius Caesar]], written around 1599, Caesar describes himself as being "as constant as the northern star", although in Caesar's time there was no constant northern star. Despite its relative brightness, it is not, as is popularly believed, the brightest star in the sky.<ref>{{Cite news |last=Geary |first=Aidan |date=June 30, 2018 |title=Look up, be patient and 'think about how big the universe is': Expert tips for stargazing this summer |url=https://www.cbc.ca/news/canada/manitoba/stargazing-constellations-how-to-1.4726939 |access-date=June 29, 2024 |work=[[Canadian Broadcasting Corporation]]}}</ref>

Polaris was referenced in the classic [[Nathaniel Bowditch]] maritime navigation book ''[[American Practical Navigator]]'' (1802), where it is listed as one of the [[navigational stars]].<ref name="BowditchAgency2002">{{cite book | title=The American practical navigator : an epitome of navigation | first1=Nathaniel | last1=Bowditch | author2=National Imagery and Mapping Agency | publisher=Paradise Cay Publications | year=2002 | isbn=978-0-939837-54-0 | page=248 | chapter=15 | author1-link=Nathaniel Bowditch | chapter-url=https://books.google.com/books?id=pXjHDnIE_ygC&pg=PR1}}</ref>

==Names==
[[Image:Polaris system.jpg|thumb|upright=0.8|This artist's concept shows: supergiant Polaris Aa, dwarf Polaris Ab, and the distant dwarf companion Polaris B.]]
The modern name ''Polaris''<ref name="IAU-CSN">[[IAU Working Group on Star Names]] {{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=2016-07-28 }}</ref> is shortened from the [[Neo-Latin]] ''stella polaris'' ("[[polar star]]"), coined in the Renaissance when the star had approached the celestial pole to within a few degrees.<ref name="gemmaefrisii"/><ref name="kunitzch"/>

[[Gemma Frisius]], writing in 1547, referred to it as ''stella illa quae polaris dicitur'' ("that star which is called 'polar'"), placing it 3° 8' from the celestial pole.<ref name="gemmaefrisii">{{cite book | title=Gemmae Frisii de astrolabo catholico liber: quo latissime patentis instrumenti multiplex usus explicatur, & quicquid uspiam rerum mathematicarum tradi possit continetur | publisher=Steelsius | date=1556 | url=https://books.google.com/books?id=8XE6AAAAcAAJ&pg=PA20 | page=20 }}</ref><ref name="kunitzch">{{cite book |last1=Kunitzsch |first1=Paul |last2=Smart |first2=Tim |date = 2006 |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations |edition = 2nd rev. |publisher = [[Sky and Telescope|Sky Publishing]] |location = Cambridge, Massachusetts |isbn = 978-1-931559-44-7 |page = 23}}</ref>

In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref>{{Cite web|url=https://www.iau.org/science/scientific_bodies/working_groups/280/|title=International Astronomical Union {{!}} IAU|website=www.iau.org|access-date=2019-01-19}}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Polaris'' for the star α Ursae Minoris Aa.<ref>{{Cite web|url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/WGSN_bulletin1.pdf|title=Bulletin of the IAU Working Group on Star Names, No. 1}}</ref>

In antiquity, Polaris was not yet the closest naked-eye star to the celestial pole, and the entire constellation of [[Ursa Minor]] was used for navigation rather than any single star. Polaris moved close enough to the pole to be the closest naked-eye star, even though still at a distance of several degrees, in the early medieval period, and numerous names referring to this characteristic as [[polar star]] have been in use since the medieval period. In Old English, it was known as ''scip-steorra'' ("ship-star").{{citation needed|date=October 2023}}

In the "[[Old English rune poem]]", the [[Tiwaz (rune)|T-rune]] is apparently associated with "a circumpolar constellation", or the planet Mars.<ref>{{cite book | first=Bruce | last=Dickins | title=Runic and heroic poems of the old Teutonic peoples | date=1915 | page=18 }}; Dickins' "a circumpolar constellation" is attributed to L. Botkine, ''La Chanson des Runes'' (1879).</ref>

In the Hindu [[Puranas]], it became personified under the name ''[[Dhruva]]'' ("immovable, fixed").<ref>{{cite book | first=Alain | last=Daniélou | author-link=Alain Daniélou | url=https://books.google.com/books?id=1HMXN9h6WX0C&pg=PA186 | title=The Myths and Gods of India: The Classic Work on Hindu Polytheism | publisher=Princeton/Bollingen (1964); Inner Traditions/Bear & Co | date=1991 | isbn=978-0-892-813544 | page=186 }}</ref>

In the later medieval period, it became associated with the [[Marian title]] of [[Our Lady, Star of the Sea|''Stella Maris'' "Star of the Sea"]] (so in [[Bartholomaeus Anglicus]], c. 1270s),<ref>{{cite book | editor1-first=James Orchard | editor1-last=Halliwell-Phillipps | title=The Works of William Shakespeare | volume=5 | date=1856 | url=https://books.google.com/books?id=7NVfAAAAcAAJ&pg=PA40 | page=40 }}</ref> due to an earlier transcription error.<ref>{{Catholic Encyclopedia|prescript=|wstitle=The Name of Mary}}</ref>

An older English name, attested since the 14th century, is [[:wikt:lodestar|lodestar]] "guiding star", cognate with the Old Norse ''leiðarstjarna'', Middle High German ''leitsterne''.<ref>{{cite book | first1=Friedrich | last1=Kluge | first2=Alfred | last2=Götze | url=https://books.google.com/books?id=R1K9DwAAQBAJ&pg=PA355 | title=Etymologisches Wörterbuch der deutschen Sprache | publisher=Walter de Gruyter | date=1943 | isbn=978-3-111-67185-7 | page=355 }}</ref>

The ancient name of the constellation Ursa Minor, ''Cynosura'' (from the Greek {{lang|grc|κυνόσουρα}} "the dog's tail"),<ref name="Ridpath2018">{{cite book | first=Ian | last=Ridpath | title=Star Tales | url=https://books.google.com/books?id=-dXYDwAAQBAJ | date=2018-06-28 | publisher=Lutterworth Press | isbn=978-0-7188-4782-1 }}</ref> became associated with the pole star in particular by the early modern period.  An explicit identification of [[Our Lady, Star of the Sea|Mary as ''stella maris'']] with the polar star (''Stella Polaris''), as well as the use of ''Cynosura'' as a name of the star, is evident in the title ''Cynosura seu Mariana Stella Polaris'' (i.e. "Cynosure, or the Marian Polar Star"), a collection of Marian poetry published by Nicolaus Lucensis (Niccolo Barsotti de Lucca) in 1655. {{citation needed|date=May 2018}}

[[File:Book of the Fixed Stars Auv0043 ursa minor cropped.jpg|thumb|Ursa Minor as depicted in the 964 Persian work [[The Book of Fixed Stars|Book of Fixed Stars]], Polaris named ''al-Judayy'' "الجدي" in the lower right.]]
Its name in traditional pre-Islamic Arab astronomy was ''al-Judayy'' الجدي ("the kid", in the sense of a juvenile [[goat]] ["le Chevreau"] in Description des Etoiles fixes),<ref>{{cite book
 | author=ʻAbd al-Raḥmān ibn ʻUmar Ṣūfī
 | title=Description des Etoiles fixes | page=45
 | year=1874 | publisher=Commissionnaires de lÁcadémie Impériale des sciences
 | url=https://books.google.com/books?id=nJRHAAAAYAAJ&pg=PA45
}}</ref> and that name was used in [[Astronomy in the medieval Islamic world|medieval Islamic astronomy]] as well.<ref>
{{cite web 
|last=Al-Sufi 
|first=AbdulRahman
|date = 964 
|title = Book Of Fixed Stars
|url = http://gallica.bnf.fr/ark:/12148/btv1b60006156/f48.item
}}</ref><ref>
{{Cite book 
|last=Schjellerup
|first=Hans
|date = 1874 
|title = Description des Etoiles fixes
|page = 45
|url = https://books.google.com/books?id=nJRHAAAAYAAJ&pg=PA45
}}</ref> In those times, it was not yet as close to the north celestial pole as it is now, and used to rotate around the pole.{{fact|date=January 2025}}

It was invoked as a symbol of steadfastness in poetry, as "steadfast star" by [[Edmund Spenser|Spenser]].
[[Shakespeare]]'s [[sonnet 116]] is an example of the symbolism of the north star as a guiding principle: "[Love] is the star to every wandering bark / Whose worth's unknown, although his height be taken."{{fact|date=January 2025}}

In ''[[Julius Caesar (play)|Julius Caesar]]'', Shakespeare has [[Julius Caesar|Caesar]] explain his refusal to grant a pardon: "I am as constant as the northern star/Of whose true-fixed and resting quality/There is no fellow in the firmament./The skies are painted with unnumbered sparks,/They are all fire and every one doth shine,/But there's but one in all doth hold his place;/So in the world" (III, i, 65–71). Of course, Polaris will not "constantly" remain as the north star due to [[Axial precession#Changing pole stars|precession]], but this is only noticeable over centuries.{{citation needed|date=May 2018}}
<!-- unreferenced names:   Phoenice, Tramontana,  Navigatoria, Star of Arcady,   Çulpan -->

In [[Inuit astronomy]], Polaris is known as ''Nuutuittuq'' (<small>[[Inuktitut syllabics|syllabics]]</small>: {{lang|iu-Cans|ᓅᑐᐃᑦᑐᖅ}}).<ref>{{Cite book|last=Penprase|first=Bryan E.|title=The Power of Stars|publisher=Springer|year=2011|isbn=978-1-4419-6802-9|location=New York, NY|page=45|chapter=Northern Circumpolar Sky from Around the World: The Arctic Inuit Sky}}</ref>

In traditional [[Lakota people|Lakota]] star knowledge, Polaris is named "Wičháȟpi Owáŋžila". This translates to "The Star that Sits Still". This name comes from a [[Lakota people|Lakota]] story in which he married Tȟapȟúŋ Šá Wíŋ, "Red Cheeked Woman". However, she fell from the heavens, and in his grief Wičháȟpi Owáŋžila stared down from "waŋkátu" (the above land) forever.<ref>{{Cite web |url=https://lastrealindians.com/news/2019/12/26/winter-solstice-is-sacred-time-a-time-to-carry-one-another-by-dakota-wind |title=Winter Solstice is Sacred Time a Time to Carry One Another by Dakota Wind |date=2019-12-27 |first=Dakota |last=Wind |work=Last Real Indians }}</ref>

The [[Cree|Plains Cree]] call the star in [[Plains Cree language|Nehiyawewin]]: ''acâhkos êkâ kâ-âhcît'' "the star that does not move" (<small>[[Cree syllabics|syllabics]]</small>: {{lang|crk|ᐊᒑᐦᑯᐢ ᐁᑳ ᑳ ᐋᐦᒌᐟ}}).<ref>{{cite web |title=Polaris |url=https://dictionary.plainscree.atlas-ling.ca/ |website=Plains Cree Dictionary |access-date=13 December 2022}}</ref>

In [[Miꞌkmaq language|Mi'kmawi'simk]] the star is named ''Tatapn''.<ref>{{cite news |last1=Lebans |first1=Jim |title=Mi'kmaw astronomer says we should acknowledge we live under Indigenous skies |url=https://www.cbc.ca/radio/quirks/oct-1-redirecting-an-asteroid-rainforest-politics-wildlife-and-covid-and-more-1.6599378/mi-kmaw-astronomer-says-we-should-acknowledge-we-live-under-indigenous-skies-1.6600279 |access-date=2022-12-21 |agency=Canadian Broadcasting Corporation |date=2022-09-29 }}</ref>

In the ancient Finnish worldview, the North Star has also been called ''taivaannapa'' and ''naulatähti'' ("the nailstar") because it seems to be attached to the firmament or even to act as a fastener for the sky when other stars orbit it. Since the starry sky seemed to rotate around it, the firmament is thought of as a wheel, with the star as the pivot on its axis. The names derived from it were ''sky pin'' and ''world pin''.{{citation needed|date=June 2023}}

==Distance==
[[Image:Stellarparallax parsec1.svg|thumb|right|Stellar parallax is the basis for the [[parsec]], which is the distance from the [[Sun]] to an [[astronomical object]] which has a [[parallax]] angle of one [[arcsecond]]. (1 [[astronomical unit|AU]] and 1 [[Parsec|pc]] are not to scale, 1 pc = about 206265 AU)]]
Many recent papers calculate the distance to Polaris at about 433 [[light-years]] (133 parsecs),<ref name="evans" /> based on parallax measurements from the [[Hipparcos]] astrometry satellite. Older distance estimates were often slightly less, and research based on high resolution spectral analysis suggests it may be up to 110 light years closer (323 ly/99 pc).<ref name="turner2012">{{cite journal|bibcode=2013ApJ...762L...8T|title=The Pulsation Mode of the Cepheid Polaris|journal=The Astrophysical Journal Letters|volume=762|issue=1|pages=L8|last1=Turner|first1=D. G.|last2=Kovtyukh|first2=V. V.|last3=Usenko|first3=I. A.|last4=Gorlova|first4=N. I.|date=2013|doi=10.1088/2041-8205/762/1/L8|arxiv = 1211.6103 |s2cid=119245441}}</ref> Polaris is the closest [[Cepheid variable]] to Earth so its physical parameters are of critical importance to the whole [[cosmic distance ladder|astronomical distance scale]].<ref name="turner2012" /> It is also the only one with a dynamically measured mass.

{| class="wikitable plainrowheaders" style="margin-right: 0; margin-left: 1em; text-align: center;"
|+ Selected distance estimates to Polaris
! scope="col" | Year
! scope="col" | Component
! scope="col" | Distance, [[light-year|ly]] ([[parsec|pc]])
! scope="col" | Notes
|-
! scope="row" | 2006
| A
| 330 ly (101 pc)
| Turner<ref name=turner/>
|-
! scope="row" | 2007{{ref label|2007|A|A}}
| A
| 433 ly (133 pc)
| Hipparcos<ref name=hipparcos2/>
|-
! scope="row" | 2008
| B
| 359 ly (110 pc)
| Usenko & Klochkova<ref name=usenko/>
|-
! scope="row" | 2013
| B
| 323 ly (99 pc)
| Turner, et al.<ref name=turner2012/>
|-
! scope="row" | 2014
| A
| ≥ 385 ly (≥ 118 pc)
| Neilson<ref name=neilson2>{{cite journal|bibcode=2014A&A...563A..48N|title=Revisiting the fundamental properties of the Cepheid Polaris using detailed stellar evolution models|journal=Astronomy & Astrophysics|volume=563|pages=A48|last1=Neilson|first1=H. R.|date=2014|doi=10.1051/0004-6361/201423482|arxiv = 1402.1177 |s2cid=119252434}}</ref>
|-
! scope="row" | 2018
| B
| 521 ly (160pc)
| Bond et al.<ref name=bond>{{cite journal|bibcode=2018ApJ...853...55B|title=Hubble Space Telescope Trigonometric Parallax of Polaris B, Companion of the Nearest Cepheid|journal=The Astrophysical Journal|volume=853|issue=1|pages=55|last1=Bond|first1=Howard E|last2=Nelan|first2=Edmund P|last3=Remage Evans|first3=Nancy|last4=Schaefer|first4=Gail H|last5=Harmer|first5=Dianne|year=2018|arxiv=1712.08139|doi=10.3847/1538-4357/aaa3f9|s2cid=118875464 |doi-access=free }}</ref>
|-
! scope="row" | 2018
| B
| 445.3 ly (136.6 pc){{ref label|2018|B|B}}
| Gaia DR2<ref name=bailer-jones/>
|-
! scope="row" | 2020
| B
| 447.6 ly (137.2pc)
| Gaia DR3<ref name="Gaia_DR3"/>
|}
{| style="margin-right: 0; margin-left: 1em;"
|-
|{{note label|2007|A|A}} New revision of observations from 1989 to 1993, first published in 1997
|-
|{{note label|2018|B|B}} Statistical distance calculated using a weak distance prior
|}

The ''Hipparcos'' spacecraft used [[stellar parallax]] to take measurements from 1989 and 1993 with the accuracy of 0.97&nbsp;[[Minute of arc|milliarcsecond]]s  (970 microarcseconds), and it obtained accurate measurements for stellar distances up to 1,000&nbsp;pc away.<ref name=hipparcos>{{Cite journal | doi = 10.1023/A:1005081918325| year = 1997| last1 = Van Leeuwen | first1 = F. | journal = Space Science Reviews| volume = 81| issue = 3/4| pages = 201–409| title = The Hipparcos Mission|bibcode = 1997SSRv...81..201V | s2cid = 189785021}}</ref> The Hipparcos data was examined again with more advanced error correction and statistical techniques.<ref name=hipparcos2>{{Cite journal | last1 = Van Leeuwen | first1 = F. | title = Validation of the new Hipparcos reduction | doi = 10.1051/0004-6361:20078357 | journal = Astronomy and Astrophysics | volume = 474 | issue = 2 | pages = 653–664 | year = 2007 |arxiv = 0708.1752 |bibcode = 2007A&A...474..653V | s2cid = 18759600 }}</ref> Despite the advantages of Hipparcos [[astrometry]], the uncertainty in its Polaris data has been pointed out and some researchers have questioned the accuracy of Hipparcos when measuring binary Cepheids like Polaris.<ref name=turner2012/> The Hipparcos reduction specifically for Polaris has been re-examined and reaffirmed but there is still not widespread agreement about the distance.<ref name=polaris-hipparcos>{{cite journal|bibcode=2013A&A...550L...3V|title=The HIPPARCOS parallax for Polaris|journal=Astronomy & Astrophysics|volume=550|pages=L3|last1=Van Leeuwen|first1=F.|date=2013|doi=10.1051/0004-6361/201220871|arxiv = 1301.0890 |s2cid=119284268}}</ref>

The next major step in high precision parallax measurements comes from [[Gaia (spacecraft)|''Gaia'']], a space astrometry mission launched in 2013 and intended to measure stellar parallax to within 25&nbsp;microarcseconds (μas).<ref name=gaia>{{cite journal|bibcode=2012MNRAS.426.2463L|title=The expected performance of stellar parametrization with Gaia spectrophotometry|journal=Monthly Notices of the Royal Astronomical Society|volume=426|issue=3|pages=2463|last1=Liu|first1=C.|display-authors=4|last2=Bailer-Jones|first2=C. A. L.|last3=Sordo|first3=R.|last4=Vallenari|first4=A.|last5=Borrachero|first5=R.|last6=Luri|first6=X.|last7=Sartoretti|first7=P.|date=2012|doi=10.1111/j.1365-2966.2012.21797.x|doi-access=free |arxiv = 1207.6005 |s2cid=1841271}}</ref> Although it was originally planned to limit Gaia's observations to stars fainter than magnitude 5.7, tests carried out during the commissioning phase indicated that Gaia could autonomously identify stars as bright as magnitude 3. When Gaia entered regular scientific operations in July 2014, it was configured to routinely process stars in the magnitude range 3 – 20.<ref>{{cite journal |bibcode=2014SPIE.9143E..0YM |title=Enabling Gaia observations of naked-eye stars |last1=Martín-Fleitas |first1=J. |last2=Sahlmann |first2=J. |last3=Mora |first3=A. |last4=Kohley |first4=R. |last5=Massart |first5=B. |last6=l'Hermitte |first6=J. |last7=Le Roy |first7=M. |last8=Paulet |first8=P. |editor-first1=Jacobus M |editor-first2=Mark |editor-first3=Giovanni G |editor-first4=Howard A |editor-last1=Oschmann |editor-last2=Clampin |editor-last3=Fazio |editor-last4=MacEwen |journal=Space Telescopes and Instrumentation 2014: Optical |series=Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave |year=2014 |volume=9143 |pages=91430Y |doi=10.1117/12.2056325 |arxiv=1408.3039 |s2cid=119112009 }}</ref> Beyond that limit, special procedures are used to download raw scanning data for the remaining 230 stars brighter than magnitude 3; methods to reduce and analyse these data are being developed; and it is expected that there will be "complete sky coverage at the bright end" with standard errors of "a few dozen μas".<ref>{{ Citation | author = T. Prusti | collaboration = GAIA Collaboration | date = 2016 | title = The ''Gaia'' mission | type = forthcoming article | journal = Astronomy and Astrophysics | volume = 595 | pages = A1 | doi = 10.1051/0004-6361/201629272 | arxiv = 1609.04153 | bibcode = 2016A&A...595A...1G | s2cid = 9271090 }}</ref> [[Gaia Data Release 2]] does not include a parallax for Polaris, but a distance inferred from it is {{val|136.6|0.5|ul=pc}} (445.5 ly) for Polaris B,<ref name=bailer-jones>{{cite journal|bibcode=2018AJ....156...58B|title=Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2|journal=The Astronomical Journal|volume=156|issue=2|pages=58|last1=Bailer-Jones|first1=C. A. L|last2=Rybizki|first2=J|last3=Fouesneau|first3=M|last4=Mantelet|first4=G|last5=Andrae|first5=R|year=2018|doi=10.3847/1538-3881/aacb21|arxiv=1804.10121|s2cid=119289017 |doi-access=free }}</ref> somewhat further than most previous estimates and several times more accurate. This was further improved to {{val|137.2|0.3|ul=pc}} (447.6 ly), upon publication of the [[Gaia Data Release 3]] catalog on 13 June 2022 which superseded Gaia Data Release 2.<ref name="Gaia_DR3">{{cite Gaia DR3|576402619921510144}}</ref>

==In popular culture==
Polaris is depicted in the [[Flag of Nunavut|flag]] and [[Coat of arms of Nunavut|coat of arms]] of the [[Canada|Canadian]] Inuit territory of [[Nunavut]],<ref>{{cite web | website=Legislative Assembly of Nunavut | title=The Coat of Arms of Nunavut. (n.d.) | url=https://assembly.nu.ca/about-legislative-assembly/coat-arms-nunavut | access-date=2021-09-15 }}</ref> the flag of the [[United States|U.S.]] states of [[Flag of Alaska|Alaska]] and [[Flag of Minnesota|Minnesota]],<ref name="s027">{{cite web | last=Swanson | first=Stephen | title=YouTuber's critique of Minnesota state flag finalists draws 1 million views | website=CBS Minnesota | date=2023-12-15 | url=https://www.cbsnews.com/minnesota/news/minnesota-state-flag-finalists-cgp-grey-youtube/ | access-date=2024-08-28}}</ref> and the flag of the U.S. city of [[Flag of Duluth, Minnesota|Duluth, Minnesota]].<ref name="Fox21">{{cite news |url= https://www.fox21online.com/2019/08/14/duluth-picks-new-city-flag/ |title= Duluth Picks New City Flag |publisher= Fox 21 |date=2019-08-14 |accessdate = 2024-09-03}}</ref><ref name="press">{{cite web |url=https://duluthmn.gov/media/13186/duluth-flag-press-release.pdf |title= City of Duluth selects new flag |first= Kate |last= Van Daele |publisher = City of Duluth |date= 2019-08-14 |accessdate= 2024-09-05}}</ref>

===Vexillology===
<gallery>
Flag of Nunavut.svg|[[Flag of Nunavut]]
Flag of Alaska.svg|[[Flag of Alaska]]
Flag of Minnesota.svg|[[Flag of Minnesota]]
Flag of Duluth, Minnesota.svg|[[Flag of Duluth, Minnesota]]
Flag of Maine.svg|[[Flag of Maine]]
Flag of Maine (1901–1909).svg|[[Flag of Maine (1901–1909)]]
Pan American Exposition Flag.svg|Flag of the [[Pan-American Exposition]] (1901)<ref>{{cite web |url=https://panam1901.org/documents/flag/pan_american_flag.html |title=Pan-American Flag |work=panam1901.org |access-date=16 November 2024}}</ref>
Francis Leopold McClintock's sledge flag (1852–1854).svg|Sledge flag used by [[Francis Leopold McClintock]] in the Arctic (1852–1854)<ref>{{cite web |url=https://www.arcticfoxtrail.com/gallery.shtml |title=Sir Francis McClintock Explorer - Arctic Fox Exhibition, Louth County Museum (Gallery Section) |author= |date= |work=arcticfoxtrail.com |access-date=14 January 2025}}</ref>
</gallery>

===Heraldry===
<gallery>
Coat of arms of Nunavut.svg|[[Coat of arms of Nunavut]]
Seal of Minnesota.svg|[[Seal of Minnesota]]
Seal of Maine.svg|[[Seal of Maine]]
Utsjoki.vaakuna.svg|Coat of arms of [[Utsjoki]]{{citation needed|date=August 2022}}
</gallery>

==Gallery==
<gallery>
UrsaMinorCC.jpg|Polaris is the brightest star in the constellation of Ursa Minor (upper right).
Ursa Major - Ursa Minor - Polaris.jpg|[[Big Dipper]] and [[Ursa Minor]] in relation to Polaris
Polaris star and companion.jpg|A view of Polaris in a small telescope. Polaris B is separated by 18 arc seconds  from the primary star, Polaris A.
File:Polaris time-lapse illustrating Cepheid type variability.gif|A 4-day time lapse of Polaris illustrating its Cepheid type variability.
</gallery>

=== Ships ===

* The [[Chinese spy ship Beijixing|Chinese spy ship ''Beijixing'']] is named after Polaris.
* [[USS Polaris]] is named after Polaris

==See also==
* [[Extraterrestrial sky]] (for the pole stars of other celestial bodies)
* [[List of nearest supergiants]]
* [[Polar alignment]]
* [[Sigma Octantis]]
* [[Polaris Flare]]
* [[Regiment of the North Pole]]

==References==
{{Reflist|30em}}

{{Commons category|Polaris}}

{{Sky|02|31|48.7|+|89|15|51|430}}
{{s-start}}
{{s-bef
| before = [[Kochab]] & [[Pherkad]]
}}
{{s-ttl
| title = [[Pole star]]
| years = [[6th century BC|500]]–[[3rd millennium|3000]]
}}
{{s-aft
| after = [[Gamma Cephei]]
}}
{{s-end}}
{{Pole star}}
{{Stars of Ursa Minor|state=collapsed}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Authority control}}

[[Category:Polaris| ]]
[[Category:F-type supergiants]]
[[Category:F-type main-sequence stars]]
[[Category:Ursa Minor]]
[[Category:Bayer objects|Ursae Minoris, Alpha]]
[[Category:Durchmusterung objects]]
[[Category:Flamsteed objects|Ursae Minoris, 01]]
[[Category:Henry Draper Catalogue objects|008890]]
[[Category:Hipparcos objects|011767]]
[[Category:Bright Star Catalogue objects|0424]]
[[Category:Stars with proper names]]
[[Category:Northern pole stars]]
[[Category:Classical Cepheid variables]]
[[Category:Suspected variables]]
[[Category:Triple star systems]]