Editing Crux

{{short description|Constellation in the southern celestial hemisphere}}
{{hatnote group|
{{other uses}}
{{redirect|Southern Cross}}
}}
{{Infobox constellation
| name = Crux
| abbreviation = Cru
| genitive = Crucis
| pronounce = {{IPAc-en|k|r|ʌ|k|s}}, genitive {{IPAc-en|ˈ|k|r|uː|s|ɪ|s}}
| symbolism = Southern Cross
| RA = {{RA|12.5}}
| dec= {{DEC|−60}}
| family = [[Hercules Family|Hercules]]
| quadrant = SQ3
| areatotal = 68
| arearank = 88th
| numbermainstars = 4
| numberbfstars = 19
| numberstarsplanets = 2
| numberbrightstars = 5
| numbernearbystars = 0
| brighteststarname = [[Alpha Crucis|Acrux]] (α Cru)
| starmagnitude = 0.87
| neareststarname = [[Eta Crucis|η Cru]]
| stardistancely = 64.22
| stardistancepc = 19.69
| numbermessierobjects = 0
| meteorshowers = [[Crucids]]
| bordering = [[Centaurus]]<br />[[Musca]]
| latmax = [[20th parallel north|20]]
| latmin = [[South Pole|90]]
| month = May
| notes=
| main stars = 5
}}
'''Crux''' ({{IPAc-en|k|r|ʌ|k|s}}) is a [[constellation]] of the [[southern sky]] that is centred on four bright stars in a [[Christian cross|cross]]-shaped [[Asterism (astronomy)|asterism]] commonly known as the '''Southern Cross'''. It lies on the southern end of the [[Milky Way]]'s visible band.  The name ''Crux'' is Latin for cross. Even though it is the [[List of constellations by area|smallest]] of all [[88 modern constellations]], Crux is among the most easily distinguished as its four main stars each have an [[apparent visual magnitude]] brighter than +2.8. It has attained a high level of cultural significance in many Southern Hemisphere states and nations.

Blue-white [[α Crucis]] (Acrux) is the most southerly member of the constellation and, at magnitude 0.8, the brightest. The three other stars of the cross appear clockwise and in order of lessening magnitude: [[β Crucis]] (Mimosa), [[γ Crucis]] (Gacrux), and [[δ Crucis]] (Imai). [[ε Crucis]] (Ginan) also lies within the cross asterism. Many of these brighter stars are members of the [[Scorpius–Centaurus association]], a large but loose group of hot, blue-white stars that appear to share common origins and motion across the southern Milky Way.

Crux contains four [[Classical Cepheid variable|Cepheid variables]], each visible to the naked eye under optimum conditions. Crux also contains the bright and colourful [[open cluster]] known as the [[Jewel Box (star cluster)|Jewel Box]] (NGC 4755) on its eastern border. Nearby to the southeast is a large [[dark nebula]] spanning 7° by 5° known as the [[Coalsack Nebula]], portions of which are mapped in the neighbouring constellations of [[Centaurus]] and [[Musca]].

==History==
The bright stars in Crux were known to the [[Ancient Greeks]], where [[Ptolemy]] regarded them as part of the constellation [[Centaurus]].<ref>{{Cite book|last1=Pasachoff|first1=J. M.|authorlink=Jay Pasachoff|last2=Menzel|first2=D. H.|authorlink2=Donald Howard Menzel|last3=Tirion|first3=W.|authorlink3=Wil Tirion|editor=R. T. Petarson|title=A Field Guide to the Stars and Planets|edition=3|year=1992|publisher=Houghton Mifflin Company|location=New York|series=The Peterson Field Guide Series|volume=15|isbn=0395537649|url=https://books.google.com/books?id=OuMLSZI1ZUIC&q=crux|page=144}}</ref>{{sfn|Staal|1988|p=247}} They were entirely visible as far north as [[Great Britain|Britain]] in the fourth millennium BC. However, the [[precession of the equinoxes]] gradually lowered the stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes.{{sfn|Ridpath|Tirion|2017|pp=134–135}} By 400&nbsp;[[Anno Domini|AD]], the stars in the constellation now called Crux never rose above the horizon throughout most of Europe. [[Dante Alighieri|Dante]] may have known about the constellation in the 14th century, as he describes an [[asterism (astronomy)|asterism]] of four bright stars in the southern sky in his ''[[Divine Comedy]]''.<ref>Dante, ''Purgatorio'', Canto I, lines 22-27, Hollander translation
::"I turned to the right and, fixing my attention
::on the other pole, I saw four stars
:: not seen but by those first on earth.
:: The very sky seemed to rejoice
:: in their bright glittering. O widowed
:: region of the north, denied that sight!"
</ref><ref name="Walker1882">{{Cite journal|title=Dante and the Southern Cross|author=Walker, J. J.|journal=Nature|volume=25|issue=636|date=22 December 1881|page=173|doi=10.1038/025217b0|s2cid=4064727|doi-access=free}}</ref> His description, however, may be allegorical, and the similarity to the constellation a coincidence.<ref name="Dante">{{Cite book|url=https://books.google.com/books?id=p_5l2FCfvF8C&q=%22almost+certain+that+Dante+did+not+know+about+that+formation%22&pg=PT315|title=The Divine Comedy|author=Dante Alighieri|isbn=9781101117996|date=2003-05-27|publisher=Penguin }}</ref>

[[Image:Southern Celestial Map of Mestre João Faras.gif|thumb|left|Depiction of the Crux by [[João Faras]] in May 1500]]

The 15th&nbsp;century Venetian navigator [[Alvise Cadamosto]] made note of what was probably the Southern Cross on exiting the [[Gambia River]] in 1455, calling it the ''carro dell'ostro'' ("southern chariot").  However, Cadamosto's accompanying diagram was inaccurate.<ref>{{cite book |quote=We likewise observed ... due south by compass, a constellation of six large bright stars, in the figure of a cross in this form ... we conjectured this to be the southern chariot, but could not expect to observe the principal star, as we had not yet lost sight of the north pole. |author=Cadamosto, A. |title=Navigatione |year=c. 1465 |edition= 1550 Ramusio |url=https://books.google.com/books?id=iZ5TZHXOnYcC&pg=RA2-PA114 |page=116r}}{{cite book |author=Cadamosto, A. |title=Navigatione |year=c. 1465 |edition= 1811 Kerr |url=https://books.google.com/books?id=YVjm2VmuOlgC&pg=PA244 |page=244}}. However, no manuscript of Cadamosto's notebook has survived, only the printed version, and the errors in the diagram may be due to the printer's decision.</ref><ref>{{cite book |author=Dekker, Elly |author-link= Elly Dekker |date=1990 |title=Annals of Science |volume=47 |pages=530–533}}</ref> Historians generally credit [[João Faras]]<ref group=lower-alpha>[[João Faras]] was an astronomer and physician of King [[Manuel I of Portugal]] who accompanied [[Pedro Álvares Cabral]] in the discovery of Brazil in 1500</ref> for being the first European to depict it correctly. Faras sketched and described the constellation (calling it "''las guardas''") in a letter written on the beaches of Brazil on 1&nbsp;May 1500 to the Portuguese monarch.<ref>{{cite book |title=Revista do Instituto Histórico e Geográfico Brasileiro |location=Rio de Janeiro |year=1843 |volume=V |issue=19 |url=https://books.google.com/books?id=fx1-Np41_90C&pg=PA342}}</ref><ref>{{cite book |author=Dekker, Elly|author-link= Elly Dekker  |date=1990 |title=Annals of Science |volume=47 |pages=533–535}}</ref>

Explorer [[Amerigo Vespucci]] seems to have observed not only the Southern Cross but also the neighboring Coalsack Nebula on his second voyage in 1501–1502.<ref>{{cite book |author=Dekker, Elly |author-link= Elly Dekker |date=1990 |title=Annals of Science |volume=47 |pages=535–543}}</ref>

Another early modern description clearly describing Crux as a separate constellation is attributed to [[Andrea Corsali]], an Italian navigator who from 1515 to 1517 sailed to China and the [[East Indies]] in an expedition sponsored by [[Manuel I of Portugal|King Manuel&nbsp;I]]. In 1516, Corsali wrote a letter to the monarch describing his observations of the southern sky, which included a rather crude map of the stars around the south celestial pole including the Southern Cross and the two Magellanic Clouds seen in an external orientation, as on a globe.<ref>{{cite book |author=Dekker, Elly|author-link= Elly Dekker  |date=1990 |title=Annals of Science |volume=47 |pages=545–548}}</ref><ref>{{cite web |title=Letter to Giuliano de Medici |year=c. 1516 |url=http://www2.sl.nsw.gov.au/archive/events/exhibitions/2010/onehundred/100-objects/Exhibit-002.htm |website=State Library of New South Wales |access-date=1 February 2018}}</ref>

[[Emery Molyneux]] and [[Petrus Plancius]] have also been cited as the first [[Celestial cartography|uranographers]] (sky mappers) to distinguish Crux as a separate constellation; their representations date from 1592, the former depicting it on his [[celestial globe]] and the latter in one of the small celestial maps on his large wall map. Both authors, however, depended on unreliable sources and placed Crux in the wrong position. Crux was first shown in its correct position on the celestial globes of [[Petrus Plancius]] and [[Jodocus Hondius]] in 1598 and 1600. Its stars were first catalogued separately from Centaurus by [[Frederick de Houtman]] in 1603.<ref>{{cite web |url=http://www.ianridpath.com/startales/crux.html |title=Ian Ridpath's Star Tales – Crux |access-date=5 August 2013}}</ref> The constellation was later adopted by [[Jakob Bartsch]] in 1624 and [[Augustin Royer]] in 1679. Royer is sometimes wrongly cited as initially distinguishing Crux.{{sfn|Staal|1988|p=247}}

==Characteristics==
[[File:Southern Cross -New Zealand-.jpg|right|thumb|upright=1.2|Southern Cross from New Zealand]]
Crux is bordered by the constellations [[Centaurus]] (which surrounds it on three sides) on the east, north and west, and [[Musca]] to the south. Covering 68&nbsp;square degrees and 0.165% of the night sky, it is the smallest of the 88 constellations.<ref name=bagnall>{{cite book |last=Bagnall |first=Philip M. |title=The Star Atlas Companion: What You Need to Know about the Constellations |publisher=Springer  |location=New York, New York |year=2012 |isbn=978-1-4614-0830-7 |pages=183–87|url=https://books.google.com/books?id=KcIg02TKW6QC&pg=PA303}}</ref> The three-letter abbreviation for the constellation, as adopted by the [[International Astronomical Union]] in 1922, is "Cru".<ref name="pa30_469">{{cite journal | last=Russell | first=Henry Norris |author-link=Henry Norris Russell | title=The New International Symbols for the Constellations | journal=Popular Astronomy | volume=30 | page=469 | bibcode=1922PA.....30..469R | year=1922 }}</ref>  The official constellation boundaries, as set by Belgian astronomer [[Eugène Joseph Delporte|Eugène Delporte]] in 1930, are defined by a polygon of four segments. In the [[equatorial coordinate system]], the [[right ascension]] coordinates of these borders lie between {{RA|11|56.13}} and {{RA|12|57.45}}, while the [[declination]] coordinates are between −55.68° and −64.70°.<ref name="boundary">{{Cite journal | title=Crux, Constellation Boundary | journal=The Constellations | publisher=International Astronomical Union | url=https://www.iau.org/public/themes/constellations/#cru | access-date=23 June 2014 | archive-date=4 June 2013 | archive-url=https://web.archive.org/web/20130604014156/https://www.iau.org/public/themes/constellations/#cru | url-status=dead }}</ref> Its totality figures at least part of the year south of the [[25th parallel north]].<ref name=tirionconst>{{cite web| url=http://www.ianridpath.com/constellations1.html | title=Constellations 1: Andromeda–Indus |author=Ian Ridpath|publisher=Self-published | access-date=23 June 2014| author-link=Ian Ridpath }}</ref>{{efn|1=While parts of the constellation technically rise above the horizon to observers between 25°N and 34°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.<ref name=tirionconst/>}}

In tropical regions Crux can be seen in the sky from April to June. Crux is exactly opposite to [[Cassiopeia (constellation)|Cassiopeia]] on the celestial sphere, and therefore it cannot appear in the sky with the latter at the same time. In this era, south of [[Cape Town]], [[Adelaide]], and [[Buenos Aires]] (the [[34th parallel south]]), Crux is circumpolar and thus always appears in the sky.

Crux is sometimes confused with the nearby [[False Cross]] asterism by stargazers. The False Cross consists of stars in Carina and Vela, is larger and dimmer, does not have a fifth star, and lacks the two prominent nearby "Pointer Stars". Between the two is the even larger and dimmer [[Diamond Cross]].

==Visibility==
[[File:Deep Crux wide field with fog.jpg|right|thumb|upright=1.2|Deep exposure of Crux, [[Coalsack Nebula]], and [[IC 2944]]]]
Crux is easily visible from the [[southern hemisphere]], south of 35th parallel at practically any time of year as circumpolar. It is also visible near the horizon from [[Tropics|tropical latitudes]] of the [[northern hemisphere]] for a few hours every night during the northern winter and spring. For instance, it is visible from [[Cancun]] or any other place at latitude 25° N or less at around 10 pm at the end of April.<ref>{{cite book | title=Field Guide to the Stars and Planets | author=Pasachoff, Jay M | year=2000 | publisher=Houghton Mifflin | isbn=978-0-395-93431-9 | page=67}}</ref><ref name=tirionconst/> There are 5 main stars.
Due to [[precession]], Crux will move closer to the South Pole in the next millennia, up to 67 degrees south declination for the middle of the constellation. However, by the year 14,000, Crux will be visible for most parts of Europe and the continental United States. Its visibility will extend to North Europe by the year 18,000 when it will be less than 30 degrees south declination.

===Use in navigation===
[[Image:Pole01-eng.svg|thumb|right|upright=1.2|Locating the south celestial pole]]
In the [[Southern Hemisphere]], the Southern Cross is frequently used for [[Celestial Navigation|navigation]] in much the same way that [[Polaris]] is used in the [[Northern Hemisphere]]. Projecting a line from [[Gacrux|γ]] to [[Acrux|α Crucis]] (the foot of the crucifix) approximately {{frac|4|1|2}} times beyond gives a point close to the Southern Celestial Pole{{sfn|Ridpath|Tirion|2017|pp=134–135}} which is also, coincidentally, where it intersects a perpendicular line taken southwards from the east–west axis of [[Alpha Centauri]] to [[Beta Centauri]], which are stars at an alike declination to Crux and of a similar width as the cross, but higher magnitude.<ref name= Grainger>{{cite book |title = Don't die in the Bundu| first1 = DH| last1 = Grainger| year = 1969| location = Cape Town| isbn = 0-86978-056-5| pages = 84–86| edition = 8th}}</ref>  [[Argentina|Argentine]] [[gaucho]]s are documented as using Crux for night orientation in the [[Pampa]]s and [[Patagonia]].

Alpha and Beta Centauri are of similar declinations (thus distance from the pole) and are often referred as the "Southern Pointers" or just "The Pointers", allowing people to easily identify the Southern Cross, the constellation of Crux.  Very few bright stars lie between Crux and the pole itself, although the constellation [[Musca]] is fairly easily recognised immediately south of Crux.<ref name= Grainger/>

===Bright stars===
Down to apparent magnitude +2.5 are 92 stars [[list of brightest stars|that shine the brightest as viewed from the Earth]]. Three of these stars are in Crux making it the most densely populated as to those stars (this being 3.26% of these 92 stars, and in turn being 19.2 times more than the expected 0.17% that would result on a homogenous distribution of all bright stars and a randomised drawing of all 88 constellations, given its area, 0.17% of the sky).

==Features==

===Stars===
{{further|List of stars in Crux}}
[[File:Constellation Crux.jpg|thumb|right|upright=1|The constellation Crux as it can be seen by the naked eye]]


Within the constellation's borders, there are 49 stars brighter than or equal to [[apparent magnitude]] 6.5.{{efn|1=Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.<ref>{{cite web|url=http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|title=The Bortle Dark-Sky Scale|last=Bortle|first=John E.|date=February 2001|work=[[Sky & Telescope]]|publisher=Sky Publishing Corporation|access-date=29 November 2014|archive-date=31 March 2014|archive-url=https://web.archive.org/web/20140331202746/http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|url-status=dead}}</ref>}}<ref name=tirionconst/> The four main stars that form the asterism are Alpha, Beta, Gamma, and Delta Crucis.
* [[α Crucis]] or Acrux is a triple star 321 light-years from Earth. A rich blue in colour, with a visual [[apparent magnitude|magnitude]] 0.8 to the unaided eye, it has two close components of a similar magnitude, 1.3 and 1.8 respectively, plus another much wider component of the 5th magnitude. The two close components are resolved in a small amateur telescope and the wide component is readily visible in a pair of binoculars.
* [[β Crucis]] or Mimosa is a blue-hued giant star of magnitude 1.3, and lies 353 light-years from Earth. It is a [[Beta Cephei]]-type [[variable star]] with a variation of less than 0.1 magnitudes.{{sfn|Ridpath|Tirion|2017|pp=134–135}}
* [[γ Crucis]] or Gacrux is an optical [[double star]]. The primary is a red-hued giant star of magnitude 1.6, 88 light-years from Earth, and is one of the closest [[red giant]]s to Earth. Its secondary component is magnitude 6.5, 264 light-years from Earth.
* [[δ Crucis]] (Imai) is a magnitude 2.8 blue-white hued star about 345 light-years from Earth.{{sfn|Ridpath|Tirion|2017|pp=134–135}} Like Mimosa it is a Beta Cepheid variable.<ref name=bagnall/>

There is also a fifth star, that is often included with the Southern Cross.
* [[ε Crucis]] (Ginan) is an orange-hued giant star of magnitude 3.6, 228 light-years from Earth.

There are several other naked-eye stars within the borders of Crux, especially:
* [[Iota Crucis]] is a visual [[double star]] 125 light-years from Earth. The primary is an orange-hued giant of magnitude 4.6 and the secondary at magnitude 9.5.
* [[Mu Crucis]] or Mu<sup>1,2</sup> Crucis is a wide double star where the components are about 370 light-years from Earth. Equally blue-white in colour, the components are magnitude 4.0 and 5.1 respectively, and are easily divisible in small amateur telescopes or large binoculars.{{sfn|Ridpath|Tirion|2017|pp=134–135}}


===Scorpius–Centaurus association===

Unusually, a total of 15 of the 23 brightest stars in Crux are spectrally blue-white B-type stars.<ref name=bagnall/> Among the five main bright stars, Delta, and probably Alpha and Beta, are likely co-moving B-type members of the [[Scorpius–Centaurus association]], the nearest [[stellar association|OB association]] to the [[Sun]].<ref name=Preibisch>{{cite journal|title=The Nearest OB Association: Scorpius–Centaurus (Sco OB2)|author1=Preibisch, T. |author2=Mamajek, E. |year=2008|journal=Handbook of Star-Forming Regions|volume=2|page=235|bibcode=2008hsf2.book..235P|arxiv=0809.0407}}</ref><ref name=mnras416_3108>{{citation | last1=Rizzuto | first1=Aaron | last2=Ireland| first2=Michael | last3=Robertson | first3=J. G. | title=Multidimensional Bayesian membership analysis of the Sco OB2 moving group | journal=Monthly Notices of the Royal Astronomical Society |date=October 2011 | volume=416 | issue=4 | pages=3108–3117 | doi=10.1111/j.1365-2966.2011.19256.x | doi-access=free | bibcode=2011MNRAS.416.3108R | arxiv=1106.2857 | s2cid=54510608 | postscript=. }}</ref> They are among the highest-mass stellar members of the Lower Centaurus–Crux subgroup of the association, with ages of roughly 10 to 20&nbsp;million years.<ref>{{cite journal | bibcode=1989A&A...216...44D |author1=de Geus, E. J. |author2=de Zeeuw, P. T. |author3= Lub, J. |name-list-style=amp | title= Physical Parameters of Stars in the Scorpio-Centaurus OB Association| journal=[[Astronomy & Astrophysics]]| volume=216 | issue=3 | year=1989 | pages=44–61 }}</ref><ref>{{cite journal |bibcode=2002AJ....124.1670M |doi=10.1086/341952 |author1=Mamajek, E. E. |author2=Meyer, M. R. |author3=Liebert, James |title=Post-T Tauri Stars in the Nearest OB Association |journal=[[Astronomical Journal]] |volume=124 |issue=3 |year=2002 |pages=1670–1694 |arxiv=astro-ph/0205417 |s2cid=16855894 }}</ref> Other members include the blue-white stars [[Zeta Crucis|Zeta]], [[Lambda Crucis|Lambda]] and both the components of the visual [[double star]], [[Mu Crucis|Mu]].<ref name=dezeeuw99>{{cite journal|title=A Hipparcos Census of Nearby OB Associations|author1=de Zeeuw, P.T. |author2=Hoogerwerf, R. |author3=de Bruijne, J.H.J. |author4=Brown, A.G.A. |author5=Blaauw, A. |year=1999|journal=Astronomical Journal|volume=117|issue=1|pages=354–99|bibcode=1999AJ....117..354D|doi=10.1086/300682|arxiv = astro-ph/9809227 |s2cid=16098861 }}</ref>

===Variable stars===

Crux contains many [[variable star]]s. It boasts four [[Cepheid variable]]s that may all reach naked eye visibility.
* [[BG Crucis]] ranges from magnitude 5.34 to 5.58 over 3.3428 days,<ref name=AAVSOBG>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10853 |title=BG Crucis |last=Watson, Christopher |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=12 March 2014}}</ref>
* [[T Crucis]] ranges from 6.32 to 6.83 over 6.73331 days,<ref name=AAVSOT>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10771 |title=T Crucis |last=Watson, Christopher |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=12 March 2014}}</ref>
* [[S Crucis]] ranges from 6.22 to 6.92 over 4.68997 days,<ref name=AAVSOS>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10770 |title=S Crucis |last=Watson, Christopher |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=12 March 2014}}</ref>
* [[R Crucis]] ranges from 6.4 to 7.23 over 5.82575 days.<ref name=AAVSOR>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10769 |title=R Crucis |last=Watson, Christopher |date=4 January 2010 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=12 March 2014}}</ref>

Other well studied variable stars includes:
* [[Lambda Crucis]] and [[Theta2 Crucis|Theta<sup>2</sup> Crucis]], that are both Beta Cepheid type variable stars.<ref name=bagnall/>
* [[BH Crucis]], also known as Welch's Red Variable, is a [[Mira variable]] that ranges from magnitude 6.6 to 9.8 over 530 days.<ref name=AAVSOBH>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=10854 |title=BH Crucis |last=Otero, Sebastian |date=6 January 2011 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=23 June 2014}}</ref>  Discovered in October 1969, it has become redder and brighter (mean magnitude changing from 8.047 to 7.762) and its period lengthened by 25% in the first thirty years since its discovery.<ref name=walker09>{{cite journal | bibcode=2009JAVSO..37...87W   | journal = J. Am. Assoc. Variable Star Obs. |volume= 37| issue = 2 |pages= 87–95 |year=2009|title= BH Crucis : Period, Magnitude, and Color Changes |author= Walker, W.S.G.}}</ref>

===Host star exoplanets in Crux===

The star [[HD 106906]] has been found to have a planet—[[HD 106906 b]]—that has one of the widest orbits of any currently known planetary-mass companions.<ref name="Bailey2014">{{cite journal |title=HD 106906 b: A planetary-mass companion outside a massive debris disk |journal=[[The Astrophysical Journal Letters]] |first1=Vanessa |last1=Bailey |first2=Tiffany |last2=Meshkat |first3=Megan |last3=Reiter |first4=Katie |last4=Morzinski |first5=Jared |last5=Males |first6=Kate Y. L. |last6=Su |first7=Philip M. |last7=Hinz |first8=Matthew |last8=Kenworthy |first9=Daniel |last9=Stark |first10=Eric |last10=Mamajek |first11=Runa |last11=Briguglio |first12=Laird M. |last12=Close |first13=Katherine B. |last13=Follette |first14=Alfio |last14=Puglisi |first15=Timothy |last15=Rodigas |first16=Alycia J. |last16=Weinberger |first17=Marco |last17=Xompero |display-authors=1 |volume=780 |issue=1 |page=L4 |date=January 2014 |arxiv=1312.1265 |doi=10.1088/2041-8205/780/1/L4 |bibcode=2014ApJ...780L...4B|s2cid=119113709 }}</ref>

===Objects beyond the Local Arm===

Crux is backlit by the multitude of stars of the Scutum-Crux Arm (more commonly called the [[Scutum-Centaurus Arm]]) of the Milky Way.  This is the main inner arm in the local radial quarter of the galaxy.  Part-obscuring this is:
* The [[Coalsack Nebula]] lies partially within Crux and partly in the neighboring constellations of [[Musca]] and [[Centaurus]].{{sfn|Ridpath|Tirion|2017|pp=134–135}} It is the most prominent [[dark nebula]] in the skies, and is easily visible to the naked eye as a prominent dark patch in the southern Milky Way. It can be found 6.5° southeast from the centre of Crux or 3° east from α Crucis. Its large area covers about 7° by 5°, and is {{convert|180|pc|ly|lk=on}} away from [[Earth]].<ref name="Franco2000">{{cite journal
|last1=Franco
|first1=G.P.A.
|year=2000
|title=Interstellar Na I D lines towards the Southern Coalsack
|journal=Monthly Notices of the Royal Astronomical Society
|volume=315
|issue=3
|pages=611–621
|bibcode=2000MNRAS.315..611F
|doi=10.1046/j.1365-8711.2000.03434.x|doi-access=free
}}</ref>

A key feature of the Scutum-Crux Arm is:
* The [[Jewel Box (star cluster)|Jewel Box]], κ Crucis Cluster or NGC 4755, is a small but bright [[open cluster]] that appears as a fuzzy star to the naked eye and is very close to the easternmost boundary of Crux: about 1° southeast of Beta Crucis. The combined or total magnitude is 4.2 and it lies at a distance of {{convert|1.95|kpc|ly|lk=on}} from Earth.{{sfn|Ridpath|Tirion|2017|pp=134–135}} The cluster was given its name by [[John Herschel]],{{sfn|Ridpath|Tirion|2017|pp=134–135}} based on the range of colours visible throughout the star cluster in his telescope. About seven million years old,<ref name="webda">{{cite web
|title=WEBDA Open cluster
|work=Results for NGC 4755
|url=http://www.univie.ac.at/webda/cgi-bin/ocl_page.cgi?dirname=ngc4755
|access-date=30 April 2019}}</ref> it is one of the youngest open clusters in the Milky Way, and it appears to have the shape of a letter 'A'. The Jewel Box Cluster is classified as Shapley class 'g' and Trumpler class 'I 3 r -' cluster; it is a very rich, centrally-concentrated cluster detached from the surrounding star field. It has more than 100 stars that range significantly in brightness.{{sfn|Levy|2005|p=87}} The brightest cluster stars are mostly [[blue supergiant]]s, though the cluster contains at least one [[red supergiant]]. [[Kappa Crucis (star)|Kappa Crucis]] is a true member of the cluster that bears its name, and is one of the brighter stars at magnitude 5.9.{{sfn|Ridpath|Tirion|2017|pp=134–135}}

==Cultural significance==
[[File:Following the Equator (Mark Twain) (page 88 crop).jpg|thumb|A depiction of The Southern Cross in Mark Twain's 1897 travelogue, "Following the Equator"]]
The most prominent feature of Crux is the distinctive asterism known as the Southern Cross. It has great significance in the cultures of the southern hemisphere, particularly of Australia, Brazil, Chile and New Zealand.<ref>{{cite web|url=https://teara.govt.nz/en/southern-cross/page-1|title=Story: Southern Cross}}</ref>

===Flags and symbols===
{{More citations needed section|date=January 2018}}
{{further|Flags depicting the Southern Cross}}
[[Image:Southern cross appearing on a number of flags.PNG|thumb|upright=1.5|Crux, appearing on a number of flags and insignia]]
Several southern countries and organisations have traditionally used Crux as a national or distinctive symbol. The four or five brightest stars of Crux appear, heraldically standardised in various ways, on the flags of [[flag of Australia|Australia]], [[flag of Brazil|Brazil]], [[flag of New Zealand|New Zealand]], [[flag of Papua New Guinea|Papua New Guinea]] and [[flag of Samoa|Samoa]]. They also appear on the flags of the [[Flag of Victoria (Australia)|Australian state of Victoria]], the [[flag of Australian Capital Territory|Australian Capital Territory]], the [[flag of Northern Territory|Northern Territory]], as well as the flag of [[Flag of Magallanes|Magallanes Region of Chile]], the flag of [[Londrina]] (Brazil) and several [[Argentina|Argentine]] provincial flags and emblems (for example, ''[[Tierra del Fuego Province (Argentina)|Tierra del Fuego]]'' and ''[[Santa Cruz Province (Argentina)|Santa Cruz]]''). The flag of the [[Mercosur]] trading zone displays the four brightest stars. Crux also appears on the [[Coat of arms of Brazil|Brazilian coat of arms]] and, {{as of | 2015 | July|alt=as of July 2015}}, on the cover of [[Brazilian passport]]s.

Five stars appear in the logo of the Brazilian football team [[Cruzeiro Esporte Clube]] and in the insignia of the [[Order of the Southern Cross]], and the cross has featured as name of the Brazilian currency (the ''[[Brazilian cruzeiro (disambiguation)|cruzeiro]]'' from 1942 to 1986 and again from 1990 to 1994). All coins of the {{as of | 2017 | alt = current}} (1998) series of the [[Brazilian real]] display the constellation.
[[File:CruzeiroDoSul-Brasil GraCruz MusHistMili-Valencia 20191204.jpg|thumb|Brazil's [[National Order of the Southern Cross]]]]
[[File:Brazilian Air Force marshal of the air rank insignia.svg|thumb|Brazilian Air Force's [[Marshal (Brazil)|''Marshal of the Air'']] military shoulder rank|100px]]
Songs and literature reference the Southern Cross, including the Argentine epic poem ''[[Martín Fierro]]''. The Argentinian singer [[Charly García]] says that he is "from the Southern Cross" in the song "No voy en tren".

The Cross gets a mention in the lyrics of the [[Brazilian National Anthem]] (1909): "''A imagem do Cruzeiro resplandece''" ("the image of the Cross shines").

The Southern Cross is mentioned in the [[Advance Australia Fair|Australian National Anthem]], "''Beneath our radiant Southern Cross we'll toil with hearts and hands''"

The Southern Cross features in the coat of arms of [[William Birdwood, 1st Baron Birdwood]], the British officer who commanded the [[Australian and New Zealand Army Corps]] during the [[Gallipoli Campaign]] of the [[First World War]].

The Southern Cross is also mentioned in the [[The Banner of Freedom|Samoan
National Anthem]].
"''Vaai 'i na fetu o lo'u a agiagia ai: Le faailoga lea o Iesu, na maliu ai mo Samoa.''" ("Look at those stars that are waving on it: This is the symbol of Jesus, who died on it for Samoa.")

The 1952-53 NBC Television Series ''[[Victory At Sea]]'' contained a musical number entitled "Beneath the Southern Cross".

"[[Southern Cross (Crosby, Stills and Nash song)|Southern Cross]]" is a single released by [[Crosby, Stills and Nash]] in 1981. It reached #18 on Billboard Hot 100 in late 1982.

"The Sign of the Southern Cross" is a song released by [[Black Sabbath]] in 1981. The song was released on the album "[[Mob Rules (album)|Mob Rules]]".

The [[Order of the Southern Cross]] is a Brazilian [[order of chivalry]] awarded to "those who have rendered significant service to the Brazilian nation".

In "[[O Sweet Saint Martin's Land]]", the lyrics mention the Southern Cross: ''Thy Southern Cross the night''.

A stylized version of Crux appears on the Australian [[Eureka Flag]]. The constellation was also used on the dark blue, shield-like patch worn by personnel of the U.S. Army's [[Americal Division]], which was organized in the Southern Hemisphere, on the island of [[New Caledonia]], and also on the blue diamond of the [[1st Marine Division (United States)|U.S. 1st Marine Division]], which fought on the Southern Hemisphere islands of [[Guadalcanal]] and [[New Britain]].

The ''Petersflagge'' flag of the [[German East Africa Company]] of 1885–1920, which included a constellation of five white five-pointed Crux "stars" on a red ground, later served as the model for symbolism associated with generic German colonial-oriented organisations: the [[Reichskolonialbund]] of 1936–1943 and the {{ill|Friends of the former German Protectorates|de|Traditionsverband ehemaliger Schutz- und Überseetruppen}} (1956/1983 to the present).

[[Southern Cross railway station|Southern Cross station]] is a major rail terminal in Melbourne, Australia.<ref>{{Cite news|url=https://www.railway-technology.com/projects/southerncrossrailway/|title=Southern Cross Railway Station, Victoria – Railway Technology|work=Railway Technology|access-date=2018-04-19|language=en-GB}}</ref>

The [[Personal Ordinariate of Our Lady of the Southern Cross]] is a personal ordinariate of the Roman Catholic Church primarily within the territory of the Australian Catholic Bishops Conference for groups of Anglicans who desire full communion with the Catholic Church in Australia and Asia.

The [[Knights of the Southern Cross]] (KSC) is a Catholic fraternal order throughout Australia.

===Various cultures===

In India, there is a story related to the creation of [[Trishanku|Trishanku Swarga]] (त्रिशंकु), meaning ''[[Chinese constellations#The Southern Asterisms (近南極星區)|Cross]]'' (Crux), created by Sage [[Vishvamitra|Vishwamitra]].<ref>{{cite web | url=https://pipanews.com/vishwamitra-created-the-parallel-universe-pipa-news/ | title=Vishwamitra created the parallel universe! PiPa News - PiPa News | date=28 May 2022 }}</ref>

In [[Chinese language|Chinese]], {{lang|zh|十字架}} ({{lang|zh-Latn|Shí Zì Jià}}), meaning ''[[Chinese constellations#The Southern Asterisms (近南極星區)|Cross]]'', refers to an asterism consisting of γ Crucis, [[Alpha Crucis|α Crucis]], [[Beta Crucis|β Crucis]] and [[Delta Crucis|δ Crucis]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|9789867332257}}.</ref>

In [[Australian Aboriginal astronomy]], Crux and the [[Coalsack Nebula|Coalsack]] mark the head of the 'Emu in the Sky' (which is seen in the dark spaces rather than in the patterns of stars) in several [[Aboriginal cultures]],<ref>Norris, R. (2007): [http://www.emudreaming.com/Examples/emu.htm The Emu in the Sky] Australian Aboriginal Astronomy website. Retrieved 2 May 2013.</ref> while Crux itself is said to be a [[Phalangeriformes|possum]] sitting in a tree ([[Wergaia|Boorong people]] of the [[Wimmera]] region of northwestern Victoria), a representation of the sky deity Mirrabooka ([[Quandamooka people]] of [[Stradbroke Island]]), a stingray ([[Yolngu|Yolngu people]] of [[Arnhem Land]]), or an eagle ([[Kaurna|Kaurna people]] of the [[Adelaide Plains]]).<ref>Musgrave, I.: [http://www.abc.net.au/news/2016-05-02/may-sky-guide/7356040 May sky guide: The Eta Aquarid meteor shower, constellations and planets] ''ABC News'', 2 May 2016. Retrieved 2 May 2016.</ref>  Two Pacific constellations also included [[Gamma Centauri]]. [[Torres Strait Islanders]] in modern-day Australia saw Gamma Centauri as the handle and the four stars as the left hand of Tagai, and the stars of Musca as the [[trident]] of the fishing spear he is holding. In [[Aranda people|Aranda]] traditions of central Australia, the four Cross stars are the talon of an [[eagle]] and Gamma Centauri as its leg.{{sfn|Staal|1988|p=249}}

Various peoples in the [[East Indies]] and Brazil viewed the four main stars as the body of a [[ray (fish)|ray.]]{{sfn|Staal|1988|p=249}} In both Indonesia and Malaysia, it is known as ''Bintang Pari'' and ''Buruj Pari'',<ref name="ASIM">{{Cite journal|last=Nurul Fatini Jaafar|year=2016|title=Kebudayaan Langit Pribumi Malayonesia|url=|journal=Kesturi|publisher=Akademi Sains Islam Malaysia|volume=26|issue=2|pages=|doi=10.13140/RG.2.2.24869.55520}}</ref> respectively ("ray stars"). This aquatic theme is also shared by an archaic name of the constellation in [[Vietnam]], where it was once known as ''sao Cá Liệt'' (the [[Leiognathidae|ponyfish]] star).<ref>{{cite book|url=http://vietnamtudien.org/dnqatv/page/n.html |title=Đại Nam quấc âm tự vị |language=vi |trans-title=Dictionnaire annamite |date=1895 |first1=Tịnh Của |last1=Huỳnh |quote=''Nam tào'': "tên sao chòm ở phía nam, cũng là sao cá liệt" ... – " the name of a constellation in the south, also known as the ponyfish star."}}</ref>

Among [[Filipino people]], the southern cross have various names pertaining to [[Spinning top|top]]s, including ''kasing'' ([[Visayan languages]]), ''paglong'' ([[Bikol language|Bikol]]), and ''pasil'' ([[Tagalog language|Tagalog]]). It is also called ''butiti'' ([[puffer fish]]) in [[Waray language|Waray]].<ref name="Mintz">{{cite journal |last1=Mintz |first1=Malcolm W. |title=Monograph 1: The Philippines at the Turn of the Sixteenth Century |journal=Intersections: Gender and Sexuality in Asia and the Pacific |date=2021 |url=http://intersections.anu.edu.au/monograph1/mintz_cover.htm |access-date=2023-06-04 |archive-date=2023-05-03 |archive-url=https://web.archive.org/web/20230503153221/http://intersections.anu.edu.au/monograph1/mintz_cover.htm |url-status=dead }}</ref>

The [[Javanese people]] of Indonesia called this constellation ''Gubug pèncèng'' ("raking hut") or ''lumbung'' ("the granary"), because the shape of the constellation was like that of a [[raking hut]].<ref>{{cite journal |last = Daldjoeni |first = N. |year = 1984  |title = Pranatamangsa, the javanese agricultural calendar – Its bioclimatological and sociocultural function in developing rural life. |journal = The Environmentalist |volume = 4 |issue = S7 |pages=15–18 |doi=10.1007/BF01907286|bibcode = 1984ThEnv...4S..15D |s2cid = 189914684 }}</ref>

The Southern Cross ([[Alpha Crucis|α]], [[Beta Crucis|β]], [[Gamma Crucis|γ]] and [[Delta Crucis|δ Crucis]]) together with [[Mu Crucis|μ Crucis]] is one of the asterisms used by [[Bugis]] sailors for navigation, called ''bintoéng bola képpang'', meaning "incomplete house star"<ref name="kelley11">{{cite book|author1=Kelley, David H. |author2=Milone, Eugene F. |author3=Aveni, A.F. |title=Exploring Ancient Skies: A Survey of Ancient and Cultural Astronomy|publisher=Springer|location=New York, New York|year=2011|page=344|isbn=978-1-4419-7623-9|url=https://books.google.com/books?id=ILBuYcGASxcC&pg=PA307}}</ref>

The [[Māori language|Māori]] name for the Southern Cross is ''Māhutonga'' and it is thought of as the anchor (''Te Punga'') of Tama-rereti's ''[[waka (canoe)|waka]]'' (the [[Milky Way]]), while the Pointers are its rope.<ref>{{cite web |url=http://www.maoridictionary.co.nz/index.cfm?wordID=10907 |title=Māori Dictionary; Waka o Tama-rereti, Te |author=<!--Staff writer(s); no by-line.--> |access-date=4 February 2013}}</ref> In [[Tonga]] it is known as ''Toloa'' ("duck"); it is depicted as a duck flying south, with one of his wings ([[Delta Crucis|δ Crucis]]) wounded because ''Ongo tangata'' ("two men", [[α Centauri|α]] and [[β Centauri]]) threw a stone at it. The Coalsack is known as ''Humu'' (the "[[triggerfish]]"), because of its shape.{{sfn|Velt|1990}} In Samoa the constellation is called ''Sumu'' ("triggerfish") because of its rhomboid shape, while α and β Centauri are called ''Luatagata'' (Two Men), just as they are in Tonga. The peoples of the [[Solomon Islands]] saw several figures in the Southern Cross. These included a knee protector and a net used to catch [[Palolo worm]]s. Neighboring peoples in the [[Marshall Islands]] saw these stars as a fish.{{sfn|Staal|1988|p=249}} [[Malay Peninsula|Peninsular]] [[Malays (ethnic group)|Malays]] also see the likeness of a fish in the Crux, particularly the [[Scomberomorus]] or its local name ''Tohok''.<ref name="ASIM" />

In [[Mapudungun]], the language of Patagonian [[Mapuche]]s, the name of the Southern Cross is ''Melipal'', which means "four stars". In [[Quechua languages|Quechua]], the language of the [[Inca]] civilization, Crux is known as "[[Chakana]]", which means literally "stair" (''chaka'', bridge, link; ''hanan'', high, above), but carries a deep symbolism within Quechua mysticism.<ref>{{cite web|url=http://www.ancientworlds.net/aw/Article/941062 |title=Chakana: Inca Cross |date=23 June 2007 |access-date=9 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120104121115/http://www.ancientworlds.net/aw/Article/941062 |archive-date=4 January 2012 }}</ref> Alpha and Beta Crucis make up one foot of the Great Rhea, a constellation encompassing [[Centaurus]] and [[Circinus]] along with the two bright stars. The Great Rhea was a constellation of the [[Bororo]] of Brazil. The [[Mocoví people]] of Argentina also saw a [[rhea (bird)|rhea]] including the stars of Crux. Their rhea is attacked by two dogs, represented by bright stars in Centaurus and Circinus. The dogs' heads are marked by [[Alpha Centauri|Alpha]] and [[Beta Centauri]]. The rhea's body is marked by the four main stars of Crux, while its head is [[Gamma Centauri]] and its feet are the bright stars of [[Musca]].{{sfn|Staal|1988|p=251}} The [[Bakairi people]] of Brazil had a sprawling constellation representing a bird snare. It included the bright stars of Crux, the southern part of Centaurus, Circinus, at least one star in [[Lupus (constellation)|Lupus]], the bright stars of Musca, [[Beta Chamaeleontis|Beta]] and the optical double star [[Delta Chamaeleontis|Delta<sup>1,2</sup> Chamaeleontis]]: and some of the stars of [[Volans]], and [[Mensa (constellation)|Mensa]].{{sfn|Staal|1988|p=250}} The [[Kalapalo people]] of [[Mato Grosso]] state in Brazil saw the stars of Crux as ''Aganagi'' angry bees having emerged from the Coalsack, which they saw as the beehive.<ref name="basso87">{{cite book|last=Basso|first=Ellen B. |title=In Favor of Deceit: A Study of Tricksters in an Amazonian Society|publisher=University of Arizona Press|location=Tucson, Arizona|date=1987|page=[https://archive.org/details/infavorofdeceits0000bass/page/360 360]|isbn=0816510229|url=https://archive.org/details/infavorofdeceits0000bass|url-access=registration}}</ref>

Among [[Tuareg people|Tuareg]]s, the four most visible stars of Crux are considered ''iggaren'', i.e. four ''[[Maerua crassifolia]]'' trees.<ref>{{Cite web|title=southern cross stars|url=http://iomcottages.com/ots8vb6u/aef346-southern-cross-stars|access-date=2021-02-02|website=iomcottages.com}}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{Cite web|title=southern cross stars|url=https://osipssausar.in/4jieznh/f17df4-southern-cross-stars|access-date=2021-02-02|website=osipssausar.in|archive-date=2021-02-13|archive-url=https://web.archive.org/web/20210213073217/https://osipssausar.in/4jieznh/f17df4-southern-cross-stars|url-status=dead}}</ref><ref>{{Cite web|title=southern cross stars|url=https://makeyourhomestandout.com/zyili4/southern-cross-stars-db60d7|access-date=2021-02-02|website=makeyourhomestandout.com}}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{Cite web|last=Tselentis|first=Chris|date=2017-03-22|title=To the Land of Dreams: Crux|url=http://tothelandofdreams.blogspot.com/2017/03/crux.html|access-date=2021-02-02|website=To the Land of Dreams}}</ref> The [[Tswana people]] of [[Botswana]] saw the constellation as ''Dithutlwa'', two giraffes – Alpha and Beta Crucis forming a male, and Gamma and Delta forming the female.<ref>{{cite journal|last=Clegg|first=Andrew|year=1986|title=Some Aspects of Tswana Cosmology|journal=Botswana Notes and Records|volume=18|pages=33–37|jstor=40979758 }}</ref>

==See also==
* [[Trishanku]]
* [[Northern Cross (asterism)|Northern Cross]]
* [[Crux (Chinese astronomy)]]

==Notes==
{{notelist}}

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

;Sources
* {{citation |title = Deep Sky Objects |last = Levy |first = David H. |publisher = Prometheus Books |year = 2005 |isbn = 1-59102-361-0 |url-access = registration |url = https://archive.org/details/deepskyobjects00davi }}
* {{citation |title = A Field Guide to the Stars and Planets |last = Pasachoff |first = Jay M. | author-link = Jay Pasachoff |year = 2006 |publisher = Houghton Mifflin}}
* {{citation |title = Stars and Planets Guide |last1 = Ridpath |first1 = Ian |last2 = Tirion |first2 = Wil |author-link1 = Ian Ridpath |author-link2 = Wil Tirion |year = 2017 |publisher = Princeton University Press |isbn = 9780691177885}}
* {{citation |title = The New Patterns in the Sky: Myths and Legends of the Stars |last = Staal |first = Julius D. W. |publisher = McDonald and Woodward Publishing Company |year = 1988 |isbn = 0939923041}}
* {{citation |last = Velt |first = Kik |title = Stars Over Tonga |publisher = 'Atenisi University |year = 1990}}

==External links==
{{Commons and category|Crux|Crux}}
* [http://www.dibonsmith.com/downunder.htm Finding the South Pole in the sky]
* [http://astrojan.nhely.hu/crux.htm The clickable Crux]
* [https://web.archive.org/web/20081014150915/http://www.teara.govt.nz/EarthSeaAndSky/Astronomy/SouthernCross/en ''Southern Cross''] in Te Ara – the Encyclopedia of New Zealand
* [http://archival.sl.nsw.gov.au/Details/archive/110324148 Andrea Corsali – Letter to Giuliano de Medici, 1516 showing the Southern Cross] at the [[State Library of NSW]]
* [http://nla.gov.au/nla.ms-ms7860 Letter of Andrea Corsali 1516–1989: with additional material] ("the first description and illustration of the Southern Cross, with speculations about Australia ...") digitised by the National Library of Australia.
* [https://classicalpoets.org/2024/02/12/the-southern-cross-a-poem-by-adam-sedia/ 'The Southern Cross': A Poem by Adam Sedia]

{{Stars of Crux}}
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[[Category:Crux| ]]
[[Category:National symbols of Australia]]
[[Category:National symbols of Brazil]]
[[Category:National symbols of New Zealand]]
[[Category:National symbols of Papua New Guinea]]
[[Category:National symbols of Samoa]]
[[Category:Southern constellations]]
[[Category:Heraldic charges]]
[[Category:Constellations listed by Petrus Plancius]]