IAU designated constellations
Constellations recognized by the International Astronomical Union
From Wikipedia, the free encyclopedia
In contemporary astronomy, 88 constellations are recognized by the International Astronomical Union (IAU).[1] Each constellation is a region of the sky bordered by arcs of right ascension and declination, together covering the entire celestial sphere. Their boundaries were officially adopted by the International Astronomical Union in 1928[2] and published in 1930.[3]
The ancient Mesopotamians and later the Greeks established most of the northern constellations in international use today, listed by the Roman-Egyptian astronomer Ptolemy. 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. In 1922, the International Astronomical Union adopted three-letter abbreviations for 89 constellations, the modern list of 88 plus Argo.[4] After this, Eugène Joseph Delporte drew boundaries for each of the 88 constellations so that every point in the sky belonged to one constellation.[1][3] Therefore, when an object is said to lay inside a particular constellation, it is understood to be positioned within these specified boundaries.
History
Some constellations are no longer recognized by the IAU but may appear in older star charts and other references. The most notable of these is Argo Navis, which was one of Ptolemy's original 48 constellations. In the 1750s, the French astronomer Nicolas Louis de Lacaille divided this into three separate constellations: Carina, Puppis, and Vela.[5]
Modern constellations
The 88 constellations depict 42 animals, 29 inanimate objects, and 17 humans or mythological characters.
Abbreviations
Each IAU constellation has an official three-letter abbreviation based on the Latin genitive form of the constellation name. As the genitive is similar to the base name, the majority of the abbreviations are the first three letters of the constellation name: Ori for Orion/Orionis, Ara for Ara/Arae, and Com for Coma Berenices. Some abbreviations use letters beyond the initial three to unambiguously identify the constellation: Aps for Apus/Apodis, CrA for Corona Australis, CrB for Corona Borealis, Crv for Corvus. (Crater is abbreviated Crt to prevent confusion with CrA.) In other cases, the abbreviation contains letters from the genitive not appearing in the base name, as in Hyi for Hydrus/Hydri, to avoid confusion with Hydra, abbreviated Hya; and Sge for Sagitta/Sagittae, to avoid confusion with Sgr for Sagittarius. When letters are taken from the second word of a two-word name, the first letter from the second word is capitalised: CMa for Canis Major, CMi for Canis Minor. Two cases are ambiguous: Leo for the constellation Leo could be mistaken for Leo Minor (abbreviated LMi), and Tri for Triangulum could be mistaken for Triangulum Australe (abbreviated TrA).[6]
In addition to the three-letter abbreviations used today, the IAU also introduced four-letter abbreviations in 1932. The four-letter abbreviations were repealed in 1955 and are now obsolete, but were included in the NASA Dictionary of Technical Terms for Aerospace Use (NASA SP-7) published in 1965.[7] These are labeled "NASA" in the table below and are included here for reference only.
List
For help with the literary English pronunciations, see the pronunciation key. There is considerable diversity in how Latinate names are pronounced in English. For traditions closer to the original, see Latin spelling and pronunciation.
Asterisms
Various other non-IAU-designated patterns, known as asterisms, exist alongside the constellations. Some are part of one larger constellation, while others consist of stars in two adjoining constellations. Examples include the Big Dipper in Ursa Major; the Teapot in Sagittarius; the Square of Pegasus in Pegasus and Andromeda; and the False Cross in Carina and Vela.
See also
Notes
- With the exception of Triangulum Australe (which was mentioned but not precisely charted earlier), these southern constellations first appeared on a globe engraved by Jodocus Hondius and published by Petrus Plancius in 1598. The constellations were based on observations by Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman, who were commissioned by Plancius to chart the southern sky on a voyage to what is now Indonesia. It is no longer clear who formed the observations into the constellations shown on the globe, and modern authors generally give credit to some combination of Kaiser, de Houtmann, and Plancius. The constellations are also widely but incorrectly attributed to Johann Bayer, since they first became widely known from his star atlas Uranometria, published in 1603.
- The constellations Camelopardalis, Columba, and Monoceros, formed by Petrus Plancius in 1592 and in 1613, are often erroneously attributed to Jacob Bartsch and Augustin Royer.
