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[[File:390px-Pleiades large.jpg|thumb|Pleiades or Messier 45]]
[[File:390px-Pleiades large.jpg|thumb|Pleiades or Messier 45]]


In astronomy, the Pleiades  or Seven Sisters (Messier 45 or M45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of [[Taurus]]. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. The celestial entity has several meanings in different cultures and traditions.
In astronomy, the [[Pleiades]] or [[Seven Sisters]] (Messier 45 or M45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of [[Taurus]]. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. The celestial entity has several meanings in different cultures and traditions.


The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years. Dust that forms a faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster (hence the alternative name Maia Nebula after the star Maia), but is now known to be an unrelated dust cloud in the interstellar medium, through which the stars are currently passing. Computer simulations have shown that the Pleiades was probably formed from a compact configuration that resembled the Orion Nebula. Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood.
The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years. Dust that forms a faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster (hence the alternative name Maia Nebula after the star Maia), but is now known to be an unrelated dust cloud in the interstellar medium, through which the stars are currently passing. Computer simulations have shown that the Pleiades was probably formed from a compact configuration that resembled the Orion Nebula. Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood.
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In Japan, the constellation is mentioned under the name Mutsuraboshi ("six stars") in the 8th century Kojiki and Manyosyu documents. The constellation is also known in Japan as Subaru (“unite”) and is depicted in the logo and name of the Subaru automobile company. The Persian equivalent is Nahid (pronounced "Naheed").
In Japan, the constellation is mentioned under the name Mutsuraboshi ("six stars") in the 8th century Kojiki and Manyosyu documents. The constellation is also known in Japan as Subaru (“unite”) and is depicted in the logo and name of the Subaru automobile company. The Persian equivalent is Nahid (pronounced "Naheed").


The rising of the Pleiades is mentioned in the Ancient Greek text Geoponica.[11] The Greeks oriented the Hecatompedon temple of 550 BC and the Parthenon of 438 BC to their rising.[12] The rising of the Pleiades before dawn (usually at the beginning of June) has long been regarded as the start of the new year in Māori culture, with the star group being known as Matariki. The rising of Matariki is celebrated as a midwinter festival in New Zealand.[13] In Hawaiian culture the cluster is known as the Makali'i and their rising shortly after sunset marks the beginning of Makahiki, a 4 month time of peace in honor of the god Lono.
The rising of the Pleiades is mentioned in the Ancient Greek text Geoponica. The Greeks oriented the Hecatompedon temple of 550 BC and the Parthenon of 438 BC to their rising.The rising of the Pleiades before dawn (usually at the beginning of June) has long been regarded as the start of the new year in Māori culture, with the star group being known as Matariki. The rising of Matariki is celebrated as a midwinter festival in New Zealand. In Hawaiian culture the cluster is known as the Makali'i and their rising shortly after sunset marks the beginning of Makahiki, a 4 month time of peace in honor of the god Lono.
Animation of proper motion in 400,000 years (cross-eyed viewing Stereogram guide cross-eyed.png). Due to technical limitations on thumbnails, you must click through to the actual image to see the animation.
Animation of proper motion in 400,000 years (cross-eyed viewing Stereogram guide cross-eyed.png). Due to technical limitations on thumbnails, you must click through to the actual image to see the animation.


Galileo Galilei was the first astronomer to view the Pleiades through a telescope. 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.
Galileo Galilei was the first astronomer to view the Pleiades through a telescope. 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. The Reverend 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 correctly surmised that the Pleiades and many other clusters of stars must be physically related.[14] When studies were first made of the stars' proper motions, 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.
The Pleiades have long been known to be a physically related group of stars rather than any chance alignment. The Reverend 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 correctly surmised that the Pleiades and many other clusters of stars must be physically related. When studies were first made of the stars' proper motions, 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 catalogue of comet-like objects, published in 1771. Along with the Orion Nebula and the 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 Lacaille, whose 1755 catalogue contained 42 objects, and so he added some bright, well-known objects to boost his list.
Charles Messier measured the position of the cluster and included it as M45 in his catalogue of comet-like objects, published in 1771. Along with the Orion Nebula and the 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 Lacaille, whose 1755 catalogue contained 42 objects, and so he added some bright, well-known objects to boost his list.
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