Editing Pleiades (section)

== 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>