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People in many cultures have imagined that the brightest stars form constellations, which are apparent pictures in the sky seeming to be persistent, being deemed also as fixed. That way, constellations have been used for centuries, and still are today, to identify regions of the night sky by both professional and amateur astronomers.
Constellation positions change throughout the year due to night on Earth occurring at gradually different portions of its orbit around the Sun. As Earth rotates toward the east, the celestial sphere appears to rotate west, with stars circling counterclockwise around the northern pole star and clockwise around the southern pole star.
Because of precession, the positions of the constellations slowly change over time. By comparing the positions of the 41 constellations against the grid circles, an accurate determination can be made of the epoch when the original observations were performed. Based upon this information, the constellations were catalogued at 125 ± 55 BC.
The change μ α, which must be multiplied by cosδ to become a component of the proper motion, is sometimes called the "proper motion in right ascension", and μ δ the "proper motion in declination". [11] If the proper motion in right ascension has been converted by cosδ, the result is designated μ α*.
The constellations along the ecliptic are called the zodiac. When explorers mapped the stars of the southern skies, European astronomers proposed new constellations for that region, as well as ones to fill gaps between the traditional constellations. Because of their Roman and European origins, every constellation has a Latin name.
Stellar drift, or the motion of stars, is a necessary result of the lack of an absolute reference frame in special relativity.. Nothing in space stands still—more precisely, standing still is meaningless without defining what "still" means.
In this list, a star is identified by a lower-case letter of the Greek alphabet, followed by the Latin name of its parent constellation. The Bayer designation uses the possessive form of a constellation's name, which in almost every case ends in is, i or ae; um if the constellation's name is plural (see genitive case for constellations). In ...
The following lists of constellations are available: IAU designated constellations – a list of the current, or "modern", constellations; Former constellations – a list of former constellations; Chinese constellations – traditional Chinese astronomy constellations; List of Nakshatras – sectors along the Moon's ecliptic