M45-The Pleiades




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M 45
Open Cluster M45 , type 'c', in Taurus

Right Ascension 03 : 47.0 (h:m)
Declination +24 : 07 (deg:m)
Distance 0.38 (kly)
Visual Brightness 1.6 (mag)
Apparent Dimension 110.0 (arc min)

Known pre-historically. Mentioned by Hesiod between 1000 and 700 B.C. The Pleiades are among those objects which are known since the earliest times. At least 6 member stars are visible to the naked eye, while under moderate conditions this number increases to 9, and under clear dark skies jumps up to more than a dozen (Vehrenberg, in his Atlas of Deep Sky Splendors, mentions that in 1579, well before the invention of the telescope, astronomer Moestlin has correctly drawn 11 Pleiades stars, while Kepler quotes observations of up to 14).

Modern observing methods have revealed that at least about 500 mostly faint stars belong to the Pleiades star cluster, spread over a 2 degree (four times the diameter of the Moon) field. Their density is pretty low, compared to other open clusters. This is one reason why the life expectation of the Pleiades cluster is also pretty low (see below).

According to Kenneth Glyn Jones, the earliest known reference of this cluster is a mention by Hesiod, about 1000 BC (according to Burnham, they were seen in connection to the agricultural seasons of that time). Homer mentions them in his Odyssee, and the Bible has three references to the Pleiades.

The Pleiades also carry the name "Seven Sisters"; according to Greek mythology, seven daughters and their parents. Their Japanese name is "Subaru", which was taken to christen the car of same name. The Persian name is "Soraya", after which the former Iranian empress was named. Old European (e.g., English and German) names indicate they were once compared to a "Hen with Chicks". Other cultures tell more and other lore of this naked-eye star cluster. Ancient Greek astronomers Eudoxus of Knidos (c. 403-350 BC) and Aratos of Phainomena (c. 270 BC) listed them as an own constellation: The Clusterers. This is also referred to by Admiral Smyth in his Bedford Catalog.