View source for Pleiades

{{Short description|Open cluster in the constellation of Taurus}}
{{About|the star cluster|other uses of Pleiades or Pléiades|Pleiades (disambiguation)}}
{{Infobox open cluster
| image         = Pleiades large.jpg
| image_size    = 280px
| caption       = A color-composite image of the Pleiades from the [[Digitized Sky Survey]]
| name          = Pleiades
| type          = [[Open Cluster]]
| epoch         = [[Epoch (astronomy)#Julian years and J2000|J2000]]
| ra            = {{RA|03|47|24}}<ref name="simbad">{{cite simbad|title=Cl Melotte 22|access-date=2007-04-20}}</ref>
| dec           = {{DEC|+24|07|00}}<ref name="simbad" />
| dist_ly       = 444 [[light-year|ly]] on average<ref name=vanleeuwen09/><ref name=majaess11/><ref name="Percival"/><ref name="Zwahlen" />
| dist_pc       = 136.2±1.2 [[parsec|pc]]
| appmag_v      = 1.6<ref name = "SEDS">[http://messier.seds.org/m/m045.html Messier 45]</ref>
| size_v        = 2° <ref name = "SEDS" />
| mass_msol     = 800
| radius_ly     = 20.34 light years<ref>{{Cite journal |last1=Danilov |first1=V. M. |last2=Seleznev |first2=A. F. |date=2020-10-01 |title=On the Motion of Stars in the Pleiades According to Gaia DR2 Data |url=https://ui.adsabs.harvard.edu/abs/2020AstBu..75..407D |journal=Astrophysical Bulletin |volume=75 |issue=4 |pages=407–424 |doi=10.1134/S1990341320040045|arxiv=2012.15289 |bibcode=2020AstBu..75..407D }}</ref>
| age           = 75 to 150 million years
| absmag_v      =
| constellation = [[Taurus (constellation)|Taurus]]
| notes =
| names        = Seven Sisters,<ref name="simbad" /> [[Messier object|M]]45,<ref name="simbad" /> [[Collinder catalogue|Cr]] 42,<ref name="simbad" /> [[Melotte catalogue|Mel]] 22<ref name="simbad" />
}}

The '''Pleiades''' ({{IPAc-en|ˈ|p|l|iː|.|ə|d|iː|z|,_|ˈ|p|l|eɪ|-|,_|ˈ|p|l|aɪ|-}}),<ref>{{MW|Pleiades}}</ref><ref>{{OED|Pleiades}}</ref> also known as '''the Seven Sisters''' and '''Messier 45''', is an [[Asterism (astronomy)|asterism]] of an [[open cluster|open star cluster]] containing young [[Stellar classification#Class B|B-type stars]] in the northwest of the constellation [[Taurus (constellation)|Taurus]]. At a distance of about 444 [[light-year]]s, it is among the nearest [[star cluster]]s to [[Earth]] and the nearest [[Messier object]] to Earth, being the most obvious star cluster to the [[naked eye]] in the [[night sky]]. It is also observed to house the reflection nebula [[NGC 1432]], an [[HII region]].<ref>{{Cite web |title=NGC 1432 (Maia Nebula) {{!}} TheSkyLive.com |url=https://theskylive.com/sky/deepsky/ngc1432-maia-nebula-object |access-date=2022-12-10 |website=theskylive.com}}</ref>

The cluster is dominated by [[OB star|hot blue luminous stars]] that have formed within the last 100 million years. [[Reflection nebula]]e around the brightest stars were once thought to be leftover material from their formation, but are now considered likely to be an unrelated dust cloud in the [[interstellar medium]] through which the stars are currently passing.<ref name="Gibson2003">{{Cite journal
|date=2003
|last1=Gibson|first1=S.J.
|last2=Nordsieck|first2=K.H.
|title=The Pleiades Reflection Nebula. II. Simple Model Constraints on Dust Properties and Scattering Geometry
|journal=[[The Astrophysical Journal]]
|volume=589
|issue=1
|pages=362–377
|bibcode=2003ApJ...589..362G
|doi=10.1086/374590|doi-access=free
}}</ref> This dust cloud is estimated to be moving at a speed of approximately 18&nbsp;km/s relative to the stars in the cluster.<ref>{{cite journal | last1 = White | first1 = Richard E. | last2 = Bally | first2 = John | title = Interstellar matter near the Pleiades. IV - The wake of the Pleiades through the interstellar medium in Taurus | journal = The Astrophysical Journal | date = May 1993 | volume = 409 | page = 234 | issn = 0004-637X | eissn = 1538-4357 | doi = 10.1086/172658 | bibcode = 1993ApJ...409..234W }}</ref>

Computer simulations have shown that the Pleiades were probably formed from a compact configuration that once resembled the [[Orion Nebula]].<ref name="Kroupa2001">{{Cite journal
|date=2001
|last1=Kroupa|first1=Pavel
|last2=Aarseth|first2=Sverre
|last3=Hurley|first3=Jarrod
|title=The formation of a bound star cluster: From the Orion nebula cluster to the Pleiades
|journal=[[Monthly Notices of the Royal Astronomical Society]]
|volume=321
|issue=4
|pages=699–712
|bibcode=2001MNRAS.321..699K
|doi=10.1046/j.1365-8711.2001.04050.x
|doi-access=free |arxiv = astro-ph/0009470 |s2cid=11660522}}</ref> Astronomers estimate that the cluster will survive for approximately another 250 million years, after which the clustering will be lost due to gravitational interactions with the galactic neighborhood.<ref name="Gendler2006">{{cite book
|date=2006
|last=Gendler|first=Robert
|title =A Year in the Life of the Universe: A Seasonal Guide to Viewing the Cosmos
|publisher = Voyageur Press
|page=54
|isbn=978-1610603409}}</ref>

Together with the open star cluster of the [[Hyades (star cluster)|Hyades]], the Pleiades form the [[Golden Gate of the Ecliptic]].

== Origin of name ==
The name, Pleiades, comes from {{langx|grc|[[wikt:Πλειάδες|Πλειάδες]]}}.<ref>{{Cite web|url=https://en.wiktionary.org/wiki/Pleiades|title=Pleiades - Wiktionary|date=5 August 2021}}</ref> It probably derives from ''plein'' ("to sail") because of the cluster's importance in delimiting the sailing season in the [[Mediterranean Sea]]: "the season of navigation began with their [[heliacal rising]]".<ref>{{cite OED |Pleiad |access-date=2022-02-15 }}</ref> In Classical Greek mythology the name was used for seven divine sisters called the [[Pleiades (Greek mythology)|Pleiades]]. In time, the name was said to be derived from that of a mythical mother, [[Pleione (mythology)|Pleione]], effectively meaning "daughters of Pleione".<ref name="Ridpath">{{cite web |url= http://www.ianridpath.com/startales/taurus2.html |title= The Pleiades – seven celestial sisters|author= [[Ian Ridpath]] |website= Ian Ridpath's Star Tales |access-date=20 November 2023}}</ref> In reality, the ancient name of the star cluster related to sailing almost certainly came first in the culture, naming of a relationship to the sister deities followed, and eventually appearing in later myths, to interpret the group name, a mother, Pleione.<ref>{{cite book | author = Robin Hard | date = 2020 | title = The Routledge Handbook of Greek Mythology: Partially Based on H.J. Rose's A Handbook of Greek Mythology | publisher = Routledge | pages = | isbn = 978-1-138-65260-6 | url = https://books.google.com/books?id=8X27tAEACAAJ}}</ref>

== Astronomical role of M45 in antiquity ==
The M45 group played an important role in ancient times for the establishment of many calendars thanks to the combination of two remarkable elements. The first, which is still valid, is its unique and easily identifiable appearance on the celestial vault near the [[ecliptic]]. The second, essential for the ancients, is that in the middle of the third millennium BC, this asterism (a prominent pattern or group of stars that is smaller than a constellation) marked the [[Equinox|vernal point]].<ref>Wilfred G. Lambert, (en) « The section AN », in : Luigi Cagni (a cura di), ''Il bilinguismo a Ebla'', Atti del convegno inter-nazionale (Napoli,, 19-22 aprile 1982), Napoli, Istituto Universitario Orientale, Dipartimento di studi asiatici, XXII (1984), 396-397</ref> (2330 BC with ecliptic latitude about +3.5° according to [[Stellarium_(software)|Stellarium]])

[[File:Nebra Scheibe.jpg|thumb|upright=1.2|On the [[Nebra sky disc]], dated circa 1600&nbsp;BC, the cluster of seven dots in the upper right portion of the disk is believed to be the Pleiades.]]
The importance of this asterism is also evident in northern Europe. The Pleiades cluster is displayed on the [[Nebra sky disc]] that was found in Germany and is dated to around 1600 BC. On the disk the cluster is represented in a high position between the Sun and the Moon.

This asterism also marks the beginning of several ancient calendars:
* In ancient India, it constitutes, in the [[Atharvaveda]], compiled around 1200-1000 BC, the first ''nakṣatra'' (Sanskrit name for lunar stations), which is called क्रृत्तिका ''Kṛttikā'', a revealing name since it literally means "the Cuttings",<ref>{{cite web|author=Gérard Huet|language=fr, skr|title=« Dictionnaire Héritage du Sanskrit », version 3.48[2023-07-01, ''s.v.'' « Kṛttikā ».|url=https://sanskrit.inria.fr/cgi-bin/SKT/sktindex.cgi?lex=SH&q=k.rttikaa&t=VH}}<!-- auto-translated by Module:CS1 translator --></ref>'' i.e. ''"Those that mark the break of the year".<ref>David Pingree & Morrissey, "On the Identification of the Yogataras of the Indian Naksatras", in ''Journal for the History of Astronomy'', Vol. 20, N° 2/61 (June 1989), p. 100.</ref> This is so before the classic list lowers this nakṣatra to third place, henceforth giving the first to the couple ''βγ Arietis'', which, notably in [[Hipparchus]], at that time, marks the equinox.
* In Mesopotamia, the ''[[MUL.APIN]] compendium'', the first known Mesopotamian astronomy treatise, discovered at Nineveh in the library of Assurbanipal and dating from no later than 627 BC, presents a list of deities [holders of stars] who stand on "the path of the Moon", a list which begins with mul.MUL.<ref>{{cite web|author=Roland Laffitte|language=fr|title=Série MUL.APIN (BM 86378)", Tab. I, iv, 31-39., on URANOS, the astronomical website of the Selefa.|url=http://www.uranos.fr/PDF/ETUDES_01_N21_FR.pdf|access-date=2023-08-03|archive-date=2023-08-12|archive-url=https://web.archive.org/web/20230812194317/http://www.uranos.fr/PDF/ETUDES_01_N21_FR.pdf|url-status=dead}}<!-- auto-translated by Module:CS1 translator --></ref>
* In Greece, the ''Πλειάδες'', are a group whose name is probably functional before having a mythological meaning, as André Lebœuffle points out, who has his preference for the explanation by the Indo-European root *''p''e/o''l''-/''pl-'' that expresses the idea of multiplicity, crowd, assembly.<ref>(en) André Le Bœuffle, ''Les Noms latins d'astres et de constellations'', éd. Paris: Les Belles Lettres, 1977, pp. 120-124.</ref>
* Similarly, the Ancient Arabs begin their old [[parapegma]] type calendar, that of the ''anwā'', with M45 under the name of الثريّا ''al-Ṯurayyā''.<ref>Charles Pellat, ''Dictons rimés'', ''anwa et mansions lunaires chez les Arabes'', in ''Arabica. Journal of arabic and islamic studies'', vol. 2 (1955) p. 19.</ref> And this before their classic calendar, that of the ''[[manāzil al-qamar]]'' or "lunar stations", also begins with the couple ''βγ Arietis'' whose name, الشرطان ''al- Šaraṭān'', is literally "the Two Marks [of entering the equinox]"<ref>Roland Laffitte, ''Essai de reconstitution du comput antique, et« le comput des des ''[[manāzil al-qamar]]'' ou stations lunaires'', in ''Le ciel des Arabes. Apport de l'uranographie arabe'', Paris : Geuthner, 2012, pp. 42-43, puis 51-60.</ref>
Although M45 is no longer at the vernal point, the asterism still remains important, both functionally and symbolically. In addition to the changes in the calendars based on the lunar stations among the Indians and the Arabs, consider the case of an ancient Yemeni calendar in which the months are designated according to an astronomical criterion that caused it to be named ''Calendar of the Pleiades'': the month of ''ḫams'', literally "five", is that during which the ''Sun'' and ''al-Ṯurayyā'', i.e. ''the Pleiades'', deviate from each other by five ''movements of the Moon'', ''i.e.'' five times the path that the "Moon" travels on average in one day and one night, to use the terminology of [[Abd al-Rahman al-Sufi]].<ref>(de) Eduard Glaser, ''Die Sternkunde der südarabischen Kabylen'', Wien : aus der Hof- und Staatsdruckerei, (s.d.) [Aus dem XCL. Bande der Sitzb. der kays. Akad. der Wissensch., II. Jänner-Heft Jahrg.1885], pp. 3-4.</ref>

== Nomenclature and mythology==
{{See also|Pleiades in folklore and literature}}
In [[Turkic Mythology]] - The Pleiades Constellation is one of the oldest cosmological figures of the Turks. Seasonal cycles in Anatolia are determined by this star group.<ref>{{Cite web|url=https://tr.wikipedia.org/wiki/%C3%9Clker_(y%C4%B1ld%C4%B1z_k%C3%BCmesi)#T%C3%BCrk_mitolojisinde|title=Turkic Mythology|website=tr.wikipedia.org |date=31 August 2024|access-date=31 August 2024}}</ref>
[[File:Seven Sisters coin Royal Australian Mint 1 dollar 2020 Reverse.jpg|thumb|Commemorative silver one dollar coin issued in 2020 by the [[Royal Australian Mint]] - on the reverse, the Seven Sisters (Pleiades) are represented as they are portrayed in an ancient story of Australian Indigenous tradition.<ref>{{Cite web|url=https://www.ramint.gov.au/publications/royal-australian-mint-looks-stars-honour-australian-indigenous-stories|title=The Royal Australian Mint looks to the stars to honour Australian Indigenous stories|website=www.ramint.gov.au|date=3 September 2020|access-date=31 December 2020}}</ref>]]
The Pleiades are a prominent sight in winter in the [[Northern Hemisphere]], and are easily visible from mid-southern latitudes. They have been known since antiquity to cultures all around the world,<ref>Julien D'Huy, Yuri Berezkin. How Did the First Humans Perceive the Starry Night? On the Pleiades. The Retrospective Methods Network Newsletter 2017, pp.100-122. https://halshs.archives-ouvertes.fr/halshs-01673386/document</ref> including the [[Celts]] ({{langx|cy|Tŵr Tewdws}}, {{langx|ga|Streoillín}}); pre-colonial [[Filipino people|Filipinos]] (who called it {{lang|tl|Mapúlon}}, {{lang|tl|Mulo‑pulo}} or {{lang|tl|Muró‑púro}}, among other names), for whom it indicated the beginning of the year;<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><ref name="MacKinlay">{{cite book |last1=MacKinlay |first1=William Egbert Wheeler |title=A Handbook and Grammar of the Tagalog Language |date=1905 |publisher=U.S. Government Printing Office |page=46}}</ref> [[Native Hawaiians|Hawaiians]] (who call them {{lang|haw|Makali{{okina}}i}}),<ref>{{Cite web|url=http://archive.hokulea.com/pdfs/Hawaiian_astronomy_I.pdf|title=Hawaiian Astronomical Concepts|last=Makemson|first=Maud|website=Hokulea.com|access-date=31 October 2018}}</ref> [[Māori culture|Māori]] (who call them {{lang|mi|[[Matariki]]}}); [[Indigenous Australians]] (from [[Australian Aboriginal astronomy#Pleiades|several traditions]]); the [[Achaemenid Empire]], whence in [[Persians]] (who called them {{transl|fa|Parvīn}} – {{lang|fa|پروین}} – or {{transl|fa|Parvī}} – {{lang|fa|پروی}});<ref>{{Cite web|url=https://www.parsi.wiki/fa/wiki/174713/%d9%be%d8%b1%d9%88%db%8c%d9%86|title=Dehkhoda Dictionary|last=Dehkhoda|first=Ali Akbar|website=Parsi Wiki}}</ref> the [[Arabs]] (who call them {{transl|ar|al-Thurayyā}}; {{lang|ar|الثريا}}<ref name="allen">{{cite book | author=Allen, Richard Hinckley | author-link=Richard Hinckley Allen | date=1963 | orig-year=1899 | title=Star Names: Their Lore and Meaning | edition=[[Reprint]] | publisher=[[Dover Publications]] Inc. | location=[[New York City|New York]], [[New York (state)|NY]] | url=https://archive.org/details/starnamestheirlo00alle | isbn=978-0-486-21079-7 | url-access=registration }}</ref>); the [[China|Chinese]] (who called them {{transl|zh|mǎo}}; {{lang|zh|昴}}); the [[Quechua people|Quechua]] (who call them [[Quyllurit'i|Qullqa]] or the storehouse); the [[Japan]]ese (who call them {{transl|ja|Subaru}}; {{lang|ja|昴}}, {{lang|ja|スバル}}); the [[Maya civilization|Maya]]; the [[Aztec]]; the [[Sioux]]; the [[Kiowa]];<ref name="Andrews2004">{{cite book |last1=Andrews |first1=Munya |title=The Seven Sisters of the Pleiades: Stories from Around the World |date=2004 |publisher=Spinifex Press |isbn=978-1876756451 |pages=149–152}}</ref><ref name="Kracht2017">{{cite book |last1=Kracht |first1=Benjamin |title=Kiowa Belief and Ritual |date=2017 |publisher=University of Nebraska Press |isbn=978-1496201461 |pages=63,75,139,189}}</ref> and the [[Cherokee]]. In [[Hinduism]], the Pleiades are known as [[Kṛttikā]] and are scripturally associated with the war deity [[Kartikeya]] and are also identified or associated with the [[Matrikas|Saptamatrika(s)]] (Seven Mothers). Hindus celebrate the first day (new moon) of the month of [[Kartik (month)|Kartik]] as [[Diwali]], a festival of abundance and lamps. {{Citation needed|date=October 2024}} The Pleiades are also mentioned three times in the [[Bible]].<ref>{{Bibleverse|Job|9:9|KJV}}, {{Bibleverse|Job|38:31|KJV}} and {{Bibleverse|Amos|5:8|KJV}}</ref><ref name="HastingsSelbie1911">{{cite book |author1=James Hastings |author2=John Alexander Selbie |author3=Andrew Bruce Davidson |author4=Samuel Rolles Driver |author5=Henry Barclay Swete |title=Dictionary of the Bible: Kir-Pleiades |url=https://books.google.com/books?id=fxZVAAAAYAAJ&pg=PA492 |year=1911 |publisher=Scribner |pages=895–896}}</ref>

[[File:Pleiades Sidereus Nuncius.png|thumb|right|upright|Galileo's drawings of the Pleiades star cluster from ''Sidereus Nuncius'']]
The earliest known depiction of the Pleiades is likely a Northern German [[Bronze Age]] artifact known as the [[Nebra sky disk]], dated to approximately 1600 BC.<ref name=BBC2008>{{cite web|url=http://www.bbc.co.uk/science/horizon/2004/stardisctrans.shtml|title=BBC - Science & Nature - Horizon - Secrets of the Star Disc|date=2004|publisher=BBC|access-date=2008-03-25}}</ref> The [[Babylonian star catalogues]] name the Pleiades {{transl|sux|<sup>MUL</sup>MUL}} ({{lang|sux|{{cuneiform|10|𒀯𒀯}}}}), meaning "stars" (literally "star star"), and they head the list of stars along the ecliptic, reflecting the fact that they were close to the point of the [[March equinox|vernal equinox]] around the twenty-third century BC. The Ancient Egyptians may have used the names "Followers" and "Ennead" in the prognosis texts of the Calendar of Lucky and Unlucky Days of papyrus Cairo 86637.<ref>{{cite journal|author=Jetsu, L.|author2=Porceddu, S.|title=Shifting Milestones of Natural Sciences: The Ancient Egyptian Discovery of Algol's Period Confirmed|journal = PLOS ONE|volume = 10 |issue=12|date = 2015|pages = e.0144140 (23pp)|doi=10.1371/journal.pone.0144140|pmid=26679699|pmc=4683080|bibcode=2015PLoSO..1044140J|arxiv = 1601.06990 |doi-access=free}}</ref> Some [[Ancient Greece|Greek]] astronomers considered them to be a distinct [[constellation]], and they are mentioned by [[Hesiod]]'s ''[[Works and Days]]'',<ref>Hesiod, ''[[Works and Days]]'', (618-23)</ref> [[Homer]]'s ''[[Iliad]]'' and ''[[Odyssey]]'',<ref name=homer>{{cite journal|bibcode=2011JAHH...14...22T|title=Astronomy and Constellations in the Iliad and Odyssey|journal=Journal of Astronomical History and Heritage|issn=1440-2807|volume=14|issue=1|pages=22|last1=Theodossiou|first1=E.|last2=Manimanis|first2=V. N.|last3=Mantarakis|first3=P.|last4=Dimitrijevic|first4=M. S.|year=2011|doi=10.3724/SP.J.1440-2807.2011.01.02 |s2cid=129824469 }}</ref> and the ''[[Geoponica]]''.<ref>{{cite web |url=http://www.ancientlibrary.com/geoponica/0028.html |title=The Geoponica (Agricultural Pursuits), page 6 (V. 1) |access-date=2011-04-22 |url-status=dead |archive-url=https://web.archive.org/web/20121012092608/http://www.ancientlibrary.com/geoponica/0028.html |archive-date=2012-10-12 }}{{dead link|date=February 2022}}</ref> The Pleiades was the most well-known "star" among pre-Islamic Arabs and so often referred to simply as "the Star" ({{transl|ar|an-Najm}}; {{lang|ar|النجم}}).<ref>{{cite thesis |author1=Danielle Kira Adams |url=https://repository.arizona.edu/handle/10150/630173 |title=Rain Stars Set, Lunar Stations Rise: Multivalent Textures of Pre-Islamic Arabian Astronomy and the Hegemonic Discourse of Order |type=PhD |publisher=University of Arizona |year=2018 |pages=105–107 }}</ref> Some scholars of [[Islam]] suggested that the Pleiades are the "star" mentioned in [[An-Najm|Surah An-Najm]] ("The Star") in the [[Quran]].<ref>Saqib Hussain, "The Prophet's Vision in Sūrat al-Najm," ''Journal of the International Qur'anic Studies Association'', '''5''' (2020): 97–132.</ref>

On numerous cylinder seals from the beginning of the first millennium BC, M45 is represented by seven points, while the ''Seven Gods'' appear, on low-reliefs of Neo-Assyrian royal palaces, wearing long open robes and large cylindrical headdresses surmounted by short feathers and adorned with three frontal rows of horns and a crown of feathers, while carrying both an ax and a knife, as well as a bow and a quiver.<ref>Jeremy Black & Anthony Green, ''Gods, Demons and Symbols of Ancient Mesopotamia'', an Illustrated Dictionary, London: British Museum Press, 1992, p. 162.</ref>

As noted by scholar [[Stith Thompson]], the constellation was "nearly always imagined" as a group of seven sisters, and their myths explain why there are only six.<ref>Thompson, Stith (1977). ''The Folktale''. University of California Press. pp. 237-238. {{ISBN|0-520-03537-2}}.</ref> Some scientists suggest that these may come from observations back when [[Pleione (star)|Pleione]] was farther from [[Atlas (star)|Atlas]] and more visible as a separate star as far back as 100,000 BC.<ref>Norris, Ray P., Norris, Barnaby R.M. (2021). Why Are There Seven Sisters?. In: Boutsikas, E., McCluskey, S.C., Steele, J. (eds) Advancing Cultural Astronomy. Historical & Cultural Astronomy. Springer, Cham. https://doi.org/10.1007/978-3-030-64606-6_11</ref>

=== Subaru ===
In [[Japan]], the cluster is mentioned under the name {{transl|ja|Mutsuraboshi}} ("six stars") in the eighth-century ''[[Kojiki]]''.<ref name="kojiki-pleiades">{{cite book|title=The Seven Sisters of the Pleiades: Stories from Around the World|first=Munya |last=Andrews |date=2004|url=https://books.google.com/books?id=3GbYg26S8pUC&pg=PA293|publisher=Spinifex Press|location=North Melbourne, Victoria, Australia|isbn=978-1-876756-45-1|page=293}}</ref> The cluster is now known in Japan as Subaru.<ref>{{cite book|title=The Seven Sisters of the Pleiades: Stories from Around the World|first=Munya |last=Andrews |date=2004|url=https://books.google.com/books?id=3GbYg26S8pUC&pg=PA293|publisher=Spinifex Press|location=North Melbourne, Victoria, Australia|isbn=978-1-876756-45-1|page=25}}</ref>

The name was chosen for that of the [[Subaru Telescope]], the {{convert|8.2|m|in|adj=on|sp=us}} flagship telescope of the [[National Astronomical Observatory of Japan]], located at the [[Mauna Kea Observatory]] on the island of [[Hawaii (island)|Hawaii]]. It had the largest [[Segmented mirror#Application|monolithic]] [[primary mirror]] in the world from its commissioning in 1998 until 2005.<ref>{{cite web|url=http://web-japan.org/kidsweb/hitech/subaru/index.html |title=The Subaru Telescope |publisher=web-japan.org |access-date=2010-09-22}}</ref>

It also was chosen as the brand name of [[Subaru]] automobiles to reflect the origins of the firm as the joining of five companies, and is depicted in the firm's six-star logo.<ref>{{cite web|title=Fuji Heavy Industries Changes Name to Subaru|url=http://www.automotive-fleet.com/news/story/2016/05/fuji-heavy-industries-changes-name-to-subaru.aspx|website=automotive-fleet.com|publisher=Automotive Fleet Magazine|access-date=24 June 2016|date=May 12, 2016}}</ref>

== Observational history ==
[[Galileo Galilei]] was the first [[astronomer]] to view the Pleiades through a [[telescope]].<ref>{{Cite web |title=Messier 45 (The Pleiades) |url=https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-45/ |url-status=live |archive-url=https://web.archive.org/web/20231116112505/https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-messier-catalog/messier-45/ |archive-date=November 16, 2023 |access-date=November 16, 2023 |website=NASA Science |language=en}}</ref> He thereby discovered that the cluster contains many stars too dim to be seen with the naked eye. He published his observations, including a sketch of the Pleiades showing 36 stars, in his treatise ''[[Sidereus Nuncius]]'' in March 1610.

The Pleiades have long been known to be a physically related group of stars rather than any chance alignment. [[John Michell]] calculated in 1767 that the probability of a chance alignment of so many bright stars was only 1 in 500,000, and so surmised that the Pleiades and many other clusters must consist of physically related stars.<ref>
{{cite journal
 |author=Michell J.
 |date=1767
 |title=An Inquiry into the probable Parallax, and Magnitude, of the Fixed Stars, from the Quantity of Light which they afford us, and the particular Circumstances of their Situation
 |journal=[[Philosophical Transactions]]
 |volume=57 |pages=234–264
 |doi=10.1098/rstl.1767.0028
|bibcode=1767RSPT...57..234M
|doi-access=free
 }}</ref> When studies were first made of the [[proper motion]]s of the stars, it was found that they are all moving in the same direction across the sky, at the same rate, further demonstrating that they were related.

[[Charles Messier]] measured the position of the cluster and included it as "M45" in his [[Messier object|catalogue]] of [[comet]]-like objects, published in 1771. Along with the [[Orion Nebula]] and the [[Beehive Cluster|Praesepe]] cluster, Messier's inclusion of the Pleiades has been noted as curious, as most of Messier's objects were much fainter and more easily confused with comets—something that seems scarcely possible for the Pleiades. One possibility is that Messier simply wanted to have a larger catalogue than his scientific rival [[Nicolas-Louis de Lacaille|Lacaille]], whose 1755 catalogue contained 42 objects, and so he added some bright, well-known objects to boost the number on his list.<ref>
{{cite web
 |author=Frommert, Hartmut
 |date=1998
 |title=Messier Questions & Answers
 |url=http://messier.seds.org/m-q&a.html#why_M42-45
 |access-date=2005-03-01
}}</ref>

[[Edme-Sébastien Jeaurat]] then drew in 1782 a map of 64 stars of the Pleiades from his observations in 1779, which he published in 1786.<ref>A New review: with literary curiosities and literary intelligence, page 326, [[Paul Henry Maty]], Printed for the author, 1783.</ref><ref>Mémoires de [[French Academy of Sciences|l'Acadêmie des sciences de l'Institut de France]], page 289, Didot frères, fils et cie, 1786.</ref><ref>Edme-Sébastien Jeaurat, ''Carte des 64 Principales Etoiles des Playades par M. Jeaurat, pour le 1.er Janvier 1786''.</ref>

== Distance ==
{{Location mark
|type=thumb|caption=Location of Pleiades (circled) in the [[night sky]]
|image=Taurus constellation map.svg|alt=|float=left|width=260
|label=|position=left
|mark=Red circle.svg|mark_width=20|mark_link=λ Tau
|x=810|y=320
}}
The distance to the Pleiades can be used as a key first step to calibrate the [[cosmic distance ladder]]. As the cluster is relatively close to the Earth, the distance should be relatively easy to measure and has been estimated by many methods. Accurate knowledge of the distance allows astronomers to plot a [[Hertzsprung–Russell diagram]] for the cluster, which, when compared with those plotted for clusters whose distance is not known, allows their distances to be estimated. Other methods may then extend the distance scale from open clusters to galaxies and clusters of galaxies, and a cosmic distance ladder may be constructed. Ultimately astronomers' understanding of the age and future evolution of the universe is influenced by their knowledge of the distance to the Pleiades. Yet some authors argue that the controversy over the distance to the Pleiades discussed below is a [[red herring]], since the cosmic distance ladder can (presently) rely on a suite of other nearby clusters where consensus exists regarding the distances as established by the ''[[Hipparcos]]'' satellite and independent means (e.g., the [[Hyades (star cluster)|Hyades]], the [[Coma Star Cluster|Coma Berenices cluster]], etc.).<ref name=majaess11>{{Cite journal|arxiv=1102.1705|last1= Majaess|first1= Daniel J.|title= Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting delta Scuti Stars|journal= Journal of the American Association of Variable Star Observers (Jaavso)|volume= 39|issue= 2|pages= 219|last2=  Turner|first2= David G.|last3=  Lane|first3= David J.|last4= Krajci|first4= Tom|date= 2011|bibcode= 2011JAVSO..39..219M}}</ref>

[[File:Astro 4D m45 cr anim.gif|upright|thumb|Animation of proper motion in 400,000 years—[[Autostereogram#3D perception|cross-eyed viewing]] [[File:Stereogram guide cross-eyed.svg|10px]] (click for viewing guide)]]

Measurements of the distance have elicited much controversy. Results prior to the launch of the ''Hipparcos'' satellite generally found that the Pleiades were approximately 135 [[parsec]]s (pc) away from Earth. Data from ''Hipparcos'' yielded a surprising result, namely a distance of only 118 pc, by measuring the [[parallax]] of stars in the cluster—a technique that should yield the most direct and accurate results. Later work consistently argued that the ''Hipparcos'' distance measurement for the Pleiades was erroneous:<ref name=majaess11/><ref name="Percival">{{cite journal
 |author=Percival, S. M.
 |author2=Salaris, M.
 |author3=Groenewegen, M. A. T.
 |date=2005
 |title=The distance to the Pleiades. Main sequence fitting in the near infrared
 |journal=[[Astronomy and Astrophysics]]
 |volume=429 |pages=887–894
 |bibcode=2005A&A...429..887P
|doi=10.1051/0004-6361:20041694
|arxiv = astro-ph/0409362
 |issue=3 |s2cid=14842664
 }}</ref><ref name="Zwahlen">
{{cite journal
 |display-authors=4
 |author=Zwahlen, N.
 |author2=North, P.
 |author3=Debernardi, Y.
 |author4=Eyer, L.
 |author5=Galland, F.
 |author6=Groenewegen, M. A. T.
 |author7=Hummel, C. A.
 |date=2004
 |title=A purely geometric distance to the binary star Atlas, a member of the Pleiades
 |journal=[[Astronomy and Astrophysics Letters]]
 |volume=425 |pages=L45
 |bibcode=2004A&A...425L..45Z
 |doi=10.1051/0004-6361:200400062
|arxiv = astro-ph/0408430
 |issue=3 |s2cid=37047575
 }}</ref><ref name=soderblom05>
{{cite journal
 |display-authors=4
 |author=Soderblom D. R.
 |author2=Nelan E.
 |author3=Benedict G. F.
 |author4=McArthur B.
 |author5=Ramirez I.
 |author6=Spiesman W.
 |author7=Jones B. F.
 |date=2005
 |title=Confirmation of Errors in Hipparcos Parallaxes from Hubble Space Telescope Fine Guidance Sensor Astrometry of the Pleiades
 |journal=[[Astronomical Journal]]
 |volume=129 |pages=1616–1624
 |bibcode=2005AJ....129.1616S
 |doi=10.1086/427860
|arxiv = astro-ph/0412093
 |issue=3 |s2cid=15354711
 }}</ref><ref>
{{cite journal
 |author=Turner, D. G.
 |date=1979
 |title=A reddening-free main sequence for the Pleiades cluster
 |journal=[[Publications of the Astronomical Society of the Pacific]]
 |volume=91 |pages=642–647
 |bibcode=1979PASP...91..642T
 |doi=10.1086/130556
|doi-access=free
 }}</ref><ref name=pan04>
{{cite journal
 |author=Pan, X.
 |date=2004
 |title=A distance of 133-137 parsecs to the Pleiades star cluster
 |journal=[[Nature (journal)|Nature]]
 |volume=427 |issue=6972
 |pages=326–328
 |bibcode=2004Natur.427..326P
 |doi=10.1038/nature02296
 |pmid=14737161
|s2cid=4383850
 }}</ref> In particular, distances derived to the cluster via the [[Hubble Space Telescope]] and infrared [[Hertzsprung–Russell diagram|color–magnitude diagram]] fitting (so-called "[[spectroscopic parallax]]") favor a distance between 135 and 140 pc;<ref name=majaess11/><ref name=soderblom05/> a dynamical distance from [[Interferometry|optical interferometric]] observations of the inner pair of stars within [[Atlas (star)|Atlas]] (a bright triple star in the Pleiades) favors a distance of 133 to 137 pc.<ref name=pan04/> However, the author of the 2007–2009 catalog of revised ''Hipparcos'' parallaxes reasserted that the distance to the Pleiades is ~120 pc and challenged the dissenting evidence.<ref name=vanleeuwen09>{{Cite journal|bibcode=2009A&A...497..209V |title=Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue |journal=[[Astronomy and Astrophysics]] |volume=497 |issue=1 |pages=209–242 |last1=Van Leeuwen |first1=F. |date=2009 |doi=10.1051/0004-6361/200811382 |arxiv = 0902.1039 |s2cid=16420237 }}</ref> In 2012, Francis and Anderson<ref>
{{cite journal
 |author=Francis C.
 |author2=Anderson E.
 |date=2012
 |title=XHIP II: clusters and associations
 |journal=[[Astronomy Letters]]
 |arxiv = 1203.4945 |bibcode = 2012AstL...38..681F
 |volume=1203
 |issue=11
 |pages=4945
 |doi=10.1134/S1063773712110023|s2cid=119285733
 }}</ref> proposed that a systematic effect on ''Hipparcos'' parallax errors for stars in clusters would bias calculation using the [[Weighted arithmetic mean|weighted mean]]; they gave a ''Hipparcos'' parallax distance of 126 pc and [[Photometry (astronomy)|photometric]] distance of 132 pc based on stars in the [[AB Doradus moving group|AB Doradus]], [[Tucana-Horologium association|Tucana-Horologium]] and [[Beta Pictoris moving group|Beta Pictoris]] moving groups, which are all similar in age and composition to the Pleiades. Those authors note that the difference between these results may be attributed to random error.
More recent results using [[very-long-baseline interferometry]] (VLBI) (August 2014), and preliminary solutions using [[Gaia (spacecraft)|Gaia]] Data Release 1 (September 2016) and Gaia Data Release 2 (August 2018), determine distances of 136.2 ± 1.2 pc,<ref name=vlbi14>
{{Cite journal
 |display-authors= 4
 |first1= Carl |last1= Melis
 |first2= Mark J. |last2= Reid
 |first3= Amy J. |last3= Mioduszewski
 |first4= John R. |last4= Stauffer
 |first5= Geoffrey |last5= Bower
 |date= 29 August 2014
 |title= A VLBI resolution of the Pleiades distance controversy
 |journal= Science
 |volume= 345 |issue= 6200 |pages= 1029–1032
 |doi= 10.1126/science.1256101
 |pmid= 25170147 |arxiv = 1408.6544 |bibcode = 2014Sci...345.1029M |s2cid= 34750246 }} See also commentary by
{{Citation
 |first1= Léo |last1= Girardi
 |date= 29 August 2014
 |title= One good cosmic measure
 |journal= Science
 |volume= 345 |issue= 6200 |pages= 1001–1002
 |doi= 10.1126/science.1258425
 |pmid= 25170136
 |bibcode = 2014Sci...345.1001G |s2cid= 5359091
 }}
</ref> 134 ± 6 pc<ref name=abrown>{{Citation
 | author = Anthony G. A. Brown
 | author2 = GAIA Collaboration
 | date = 2016
 | title = Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
 | type = forthcoming article
 | journal = Astronomy and Astrophysics
 | doi = 10.1051/0004-6361/201629512
 | url = http://www.aanda.org/articles/aa/pdf/forth/aa29512-16.pdf
 | access-date = 14 September 2016
 | bibcode=2016A&A...595A...2G
 | volume=595
 | page=A2
 | arxiv = 1609.04172
 | s2cid = 1828208
 }}</ref> and 136.2 ± 5.0 pc,<ref name="Abramson2018">{{cite journal |last1=Abramson |first1=Guillermo |title=The Distance to the Pleiades According to Gaia DR2 |journal=Research Notes of the AAS |date=20 August 2018 |volume=2 |issue=3 |pages=150 |doi=10.3847/2515-5172/aada8b|bibcode=2018RNAAS...2..150A |doi-access=free |hdl=11336/94435 |hdl-access=free }}</ref> respectively. The Gaia Data Release&nbsp;1 team were cautious about their result, and the VLBI authors assert "that the ''Hipparcos''-measured distance to the Pleiades cluster is in error".

The most recent distance estimate of the distance to the Pleiades based on the [[Gaia Data Release 3]] is {{val|135.74|0.10|u=pc}}.<ref name="Alfonso2023">{{cite journal |last1=Alfonso |first1=Jeison |last2=García-Varela |first2=Alejandro |title=A Gaia astrometric view of the open clusters Pleiades, Praesepe, and Blanco 1 |journal=Astronomy & Astrophysics |date=September 2023 |volume=677 |pages=A163 |doi=10.1051/0004-6361/202346569|arxiv=2304.00164 |bibcode=2023A&A...677A.163A }}</ref>

{| class="wikitable plainrowheaders" style="margin-right: 0; margin-left: 1em; text-align: center;"
|+ Selected distance estimates to the Pleiades
! scope="col" | Year
! scope="col" | Distance ([[parsec|pc]])
! scope="col" | Notes
|-
! scope="row" | 1999
| 125
| ''[[Hipparcos]]''<ref name=hipparcos1999>{{cite journal|bibcode=1999A&A...341L..71V|title=HIPPARCOS distance calibrations for 9 open clusters|journal=Astronomy and Astrophysics|volume=341|pages=L71|last1=Van Leeuwen|first1=Floor|year=1999}}</ref>
|-
! scope="row" | 2004
| 134.6 ± 3.1
| Hubble [[Fine Guidance Sensor (HST)|Fine Guidance Sensor]]<ref name="soderblom05" />
|-
! scope="row" | 2009
| 120.2 ± 1.9
| Revised ''Hipparcos''<ref name=vanleeuwen09/>
|-
! scope="row" | 2014
| 136.2 ± 1.2
| [[Very-long-baseline interferometry]]<ref name=vlbi14/>
|-
! scope="row" | 2016
| 134 ± 6
| [[Gaia Data Release 1]]<ref name=abrown/>
|-
! scope="row" | 2018
| 136.2 ± 5.0
| [[Gaia Data Release 2]]<ref name=Abramson2018/>
|-
! scope="row" | 2023
| {{val|135.74|0.10|u=pc}}
| [[Gaia Data Release 3]]<ref name="Alfonso2023"/>
|-
|}

== Composition ==
[[File:M45map.jpg|thumb|right|A map of the Pleiades]]
The cluster core radius is approximately 8 [[light-year]]s and [[tidal radius]] is approximately 43 light-years. The cluster contains more than 1,000 statistically confirmed members, not counting the number that would be added if all [[binary star]]s could be resolved.<ref name="Adams, Joseph D. 2053">
{{cite journal
 |display-authors=4
 |author=Adams, Joseph D.
 |author2=Stauffer, John R.
 |author3=Monet, David G.
 |author4=Skrutskie, Michael F.
 |author5=Beichman, Charles A.
 |date=2001
 |title=The Mass and Structure of the Pleiades Star Cluster from 2MASS
 |journal=[[Astronomical Journal]]
 |volume=121 |pages=2053–2064
 |bibcode=2001AJ....121.2053A
 |doi=10.1086/319965
|arxiv = astro-ph/0101139
 |issue=4 |s2cid=17994583
 }}</ref> Its light is dominated by young, hot [[stellar classification|blue stars]], up to 14 of which may be seen with the naked eye, depending on local observing conditions and visual acuity of the observer. The brightest stars form a shape somewhat similar to that of [[Ursa Major]] and [[Ursa Minor]]. The total mass contained in the cluster is estimated to be approximately 800 [[solar mass]]es and is dominated by fainter and redder stars{{Clarification needed|reason=Do we mean that the MASS consists mostly of fainter and redder stars, or that the POPULATION consists mostly of fainter and redder stars?|date=May 2024}}.<ref name="Adams, Joseph D. 2053"/> An estimate of the frequency of [[binary star]]s in the Pleiades is approximately 57%.<ref>{{cite journal|doi=10.3847/1538-4357/ac1585|title=Long-term Spectroscopic Survey of the Pleiades Cluster: The Binary Population|year=2021|last1=Torres|first1=Guillermo|last2=Latham|first2=David W.|last3=Quinn|first3=Samuel N.|journal=The Astrophysical Journal|volume=921|issue=2|page=117|arxiv=2107.10259|bibcode=2021ApJ...921..117T|s2cid=236171384 |doi-access=free }}</ref>

The cluster contains many [[brown dwarf]]s, such as [[Teide 1]]. These are objects with less than approximately 8% of the [[Sun]]'s mass, insufficient for [[nuclear fusion]] reactions to start in their cores and become proper stars. They may constitute up to 25% of the total population of the cluster, although they contribute less than 2% of the total mass.<ref>
{{cite journal
 |author=Moraux, E.
 |author2=Bouvier, J.
 |author3=Stauffer, J. R.
 |author4=Cuillandre, J.-C.
 |date=2003
 |title=Brown in the Pleiades cluster: Clues to the substellar mass function
 |journal=[[Astronomy and Astrophysics]]
 |volume=400 |pages=891–902
 |bibcode=2003A&A...400..891M
 |doi=10.1051/0004-6361:20021903
|arxiv = astro-ph/0212571
 |issue=3 |s2cid=17613925
 }}</ref> Astronomers have made great efforts to find and analyze brown dwarfs in the Pleiades and other young clusters, because they are still relatively bright and observable, while brown dwarfs in older clusters have faded and are much more difficult to study.

== Brightest stars ==
The brightest stars of the cluster are named the [[Pleiades (Greek mythology)|Seven Sisters]] in early [[Greek mythology]]: [[Sterope (Pleiad)|Sterope]], [[Merope (Pleiades)|Merope]], [[Electra (Pleiad)|Electra]], [[Maia (mythology)|Maia]], [[Taygete|Taygeta]], [[Celaeno (Pleiad)|Celaeno]], and [[Alcyone (Pleiades)|Alcyone]]. Later, they were assigned parents, [[Pleione (mythology)|Pleione]] and [[Atlas (mythology)|Atlas]].<ref name="Ridpath" /> As daughters of Atlas, the [[Hyades (mythology)|Hyades]] were sisters of the Pleiades.

The following table gives details of the brightest stars in the cluster:
{{Clear}}
{| class="wikitable sortable"
|+'''Pleiades bright stars'''
|-
! class="unsortable"| Name
! class="unsortable"| Pronunciation ([[Help:IPA/English|IPA]])
! class="unsortable"| [[Star designation|Designation]]
! [[Apparent magnitude]]
! [[Stellar classification]]
! Distance (ly)<ref name="Gaia">{{Cite DR2}}</ref>
|-
| [[Alcyone (star)|Alcyone]]
| {{IPAc-en|æ|l|ˈ|s|aɪ|.|ə|n|iː}}
| Eta (25) Tauri
| 2.86
| B7IIIe
| {{val|409|50}}
|-
| [[Atlas (star)|Atlas]]
| {{IPAc-en|ˈ|æ|t|l|ə|s}}
| 27 Tauri
| 3.62
| B8III
| {{val|387|26}}
|-
| [[Electra (star)|Electra]]
| {{IPAc-en|ə|ˈ|l|ɛ|k|t|r|ə}}
| 17 Tauri
| 3.70
| B6IIIe
| {{val|375|23}}
|-
| [[Maia (star)|Maia]]
| {{IPAc-en|ˈ|m|eɪ|.|ə}}
| 20 Tauri
| 3.86
| B7III
| {{val|344|25}}
|-
| [[Merope (star)|Merope]]
| {{IPAc-en|ˈ|m|ɛr|ə|p|iː}}
| 23 Tauri
| 4.17
| B6IVev
| {{val|344|16}}
|-
| [[Taygeta (star)|Taygeta]]
| {{IPAc-en|t|eɪ|ˈ|ɪ|dʒ|ə|t|ə}}
| 19 Tauri
| 4.29
| B6IV
| {{val|364|16}}
|-
| [[Pleione (star)|Pleione]]
| {{IPAc-en|ˈ|p|l|iː|ə|n|iː|,_|'|p|l|aɪ|-}}
| 28 (BU) Tauri
| 5.09 [[Variable star|(var.)]]
| B8IVpe
| {{val|422|11}}
|-
| [[Celaeno (star)|Celaeno]]
| {{IPAc-en|s|ə|ˈ|l|iː|n|oʊ}}
| 16 Tauri
| 5.44
| B7IV
| {{val|434|10}}
|-
| [[21 Tauri|Asterope or Sterope I]]
| {{IPAc-en|ə|ˈ|s|t|ɛr|ə|p|iː}}
| 21 Tauri
| 5.64
| B8Ve
| {{val|431.1|7.5}}
|-
| —
| —
| [[18 Tauri]]
| 5.66
| B8V
| {{val|444|7}}
|-
| [[22 Tauri|Sterope II]]
| {{IPAc-en|ˈ|s|t|ɛr|ə|p|iː}}
| 22 Tauri
| 6.41
| B9V
| {{val|431.1|7.5}}
|-
| —
| —
| [[HD 23753]]
| 5.44
| B9Vn
| {{val|420|10}}
|-
| —
| —
| [[HD 23923]]
| 6.16
| B8V
| 374.04
|-
| —
| —
| [[HD 23853]]
| 6.59
| B9.5V
| 398.73
|-
| —
| —
| [[HD 23410]]
| 6.88
| A0V
| 395.82
|}

== Age and future evolution ==
[[File:Pleiades-motion.png|thumb|Stars of Pleiades with color and 10,000-year backward proper motion shown]]
Ages for star clusters may be estimated by comparing the [[Hertzsprung–Russell diagram]] for the cluster with theoretical models of [[stellar evolution]]. Using this technique, ages for the Pleiades of between 75 and 150 million years have been estimated. The wide spread in estimated ages is a result of uncertainties in stellar evolution models, which include factors such as [[convective overshoot]], in which a [[convection|convective]] zone within a star penetrates an otherwise non-convective zone, resulting in higher apparent ages.{{citation needed|date=September 2023}}

Another way of estimating the age of the cluster is by looking at the lowest-mass objects. In normal [[main-sequence]] stars, [[lithium]] is rapidly destroyed in [[nuclear fusion]] reactions. [[Brown dwarf]]s can retain their lithium, however. Due to lithium's very low ignition temperature of 2.5 × 10<sup>6</sup> K, the highest-mass brown dwarfs will burn it eventually, and so determining the highest mass of brown dwarfs still containing lithium in the cluster may give an idea of its age. Applying this technique to the Pleiades gives an age of about 115 million years.<ref>
{{cite journal |last1=Basri |first1=Gibor |last2=Marcy |first2=Geoffrey W. |last3=Graham |first3=James R. |title=Lithium in Brown Dwarf Candidates: The Mass and Age of the Faintest Pleiades Stars |year=1996 |journal=[[The Astrophysical Journal]] |volume=458 |pages=600–609 |doi=10.1086/176842 |bibcode=1996ApJ...458..600B }}</ref><ref>
{{cite journal
 |display-authors=4
 |author=Ushomirsky, G.
 |author2=Matzner, C.
 |author3=Brown, E.
 |author4=Bildsten, L.
 |author5=Hilliard, V.
 |author6=Schroeder, P.
 |date=1998
 |title=Light-Element Depletion in Contracting Brown Dwarfs and Pre-Main-Sequence Stars
 |journal=[[Astrophysical Journal]]
 |volume=497 |issue=1
 |pages=253–266
 |bibcode=1998ApJ...497..253U
 |doi=10.1086/305457
|arxiv = astro-ph/9711099 |s2cid=14674869
 }}</ref>

The cluster is [[relative motion|slowly moving]] in the direction of the feet of what is currently the constellation of [[Orion (constellation)|Orion]]. Like most open clusters, the Pleiades will not stay gravitationally bound forever. Some component stars will be ejected after close encounters with other stars; others will be stripped by tidal gravitational fields. Calculations suggest that the cluster will take approximately 250 million years to disperse, because of gravitational interactions with [[molecular cloud|giant molecular clouds]] and the [[Spiral galaxy|spiral arms]] of our galaxy hastening its demise.<ref>
{{cite journal
 |author=Converse, Joseph M.
 |author2=Stahler, Steven W.
 |name-list-style=amp
 |date=2010
 |title=The dynamical evolution of the Pleiades
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=405 |issue=1
 |pages=666–680
 |doi=10.1111/j.1365-2966.2010.16505.x
 |doi-access=free
 |bibcode=2010MNRAS.405..666C
 |arxiv = 1002.2229 |s2cid=54611261
 }}</ref>

== Reflection nebulosity ==
[[File:Reflection nebula IC 349 near Merope.jpg|thumb|upright=1.0|[[Hubble Space Telescope]] image of reflection nebulosity near [[Merope (star)|Merope]] ([[IC 349]])]]

With larger amateur telescopes, the nebulosity around some of the stars may be easily seen, especially when long-exposure photographs are taken. Under ideal observing conditions, some hint of nebulosity around the cluster may be seen even with small telescopes or average binoculars. It is a [[reflection nebula]], caused by dust reflecting the blue light of the hot, young stars.

It was formerly thought that the dust was left over from the [[star formation|formation]] of the cluster, but at the age of approximately 100 million years generally accepted for the cluster, almost all the dust originally present would have been dispersed by [[radiation pressure]]. Instead, it seems that the cluster is simply passing through a particularly dusty region of the [[interstellar medium]].<ref name="Gibson2003" />

Studies show that the dust responsible for the nebulosity is not uniformly distributed, but is concentrated mainly in two layers along the line of sight to the cluster. These layers may have been formed by deceleration due to [[radiation]] pressure as the dust has moved toward the stars.<ref>
{{cite journal
 |author=Gibson, Steven J.
 |author2=Nordsieck, Kenneth H.
 |date=2003
 |title=The Pleiades Reflection Nebula. II. Simple Model Constraints on Dust Properties and Scattering Geometry
 |journal=[[Astrophysical Journal]]
 |volume=589 |issue=1
 |pages=362–377
 |bibcode=2003ApJ...589..362G
 |doi=10.1086/374590
|doi-access=free
 }}</ref>

== Possible planets ==
Analyzing deep-infrared images obtained by the [[Spitzer Space Telescope]] and [[Gemini Observatory|Gemini North telescope]], astronomers discovered that one of the stars in the cluster, [[HD 23514]], which has a mass and luminosity a bit greater than that of the Sun, is surrounded by an extraordinary number of hot dust particles. This could be evidence for planet formation around HD 23514.<ref>
{{cite web
 |author=ScienceDaily
 |date=2007
 |title=Planets Forming In Pleiades Star Cluster, Astronomers Report
 |url=https://www.sciencedaily.com/releases/2007/11/071114203718.htm
 |access-date=2012-11-15
}}</ref>

== Videos ==
{{multiple image
| align     = left
| direction = horizontal
| image1    = Pleiades.ogg
| width1    = 300
| alt1      =
| caption1  = A 3-D model of the Pleiades open cluster from the Galaxy Map app (iOS/Android)
}}
{{Clear}}

== Gallery ==
<gallery widths="200" heights="250">
File:Pleiades.png| A star chart of the Pleiades and their nebulae
File:M45 - The Pleiades.jpg|A widefield view of the Pleiades showing the surrounding dust, image taken with 7 hours of total exposure time
File:Pleiades Deep dive.jpg|A widefield view of the Pleiades showing the surrounding dust, image taken with 56 hours of total exposure time
</gallery>

== See also ==
* {{section link|Australian Aboriginal astronomy|Seven Sisters}}
* [[Stozhary]]
* [[Matrikas]]
* [[Saptarishi#Astronomy|The Seven Sages]]

== References ==
{{Reflist|25em}}

== External links ==
{{Wiktionary|Pleiades}}
{{Commons category|Pleiades (star cluster)}}
{{Wikiquote}}
* {{WikiSky|name=The Pleiades}}
* [http://messier.seds.org/m/m045.html Information on the Pleiades from SEDS]

{{Messier objects}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Authority control}}

{{Sky|03|47|24|+|24|07|00|440}}

{{DEFAULTSORT:Pleiades (Star Cluster)}}
[[Category:Astronomical objects known since antiquity]]
[[Category:Messier objects]]
[[Category:NGC objects]]
[[Category:Orion–Cygnus Arm]]
[[Category:Pleiades|*]]
[[Category:Taurus (constellation)]]