In contemporary

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

, 88

constellations A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellatio ...

are recognized by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

(IAU). Each constellation is a region of the sky, bordered by arcs of

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the ( hour circle of the) point in question above the earth. When pai ...

and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of t ...

. Together they cover the

celestial sphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...

, with their boundaries adopted officially by the International Astronomical Union in 1928 and published in 1930. The ancient Sumerians, and later the

Greeks The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group and nation indigenous to the Eastern Mediterranean and the Black Sea regions, namely Greece, Greek Cypriots, Cyprus, Greeks in Albania, Albania, Greeks in Italy, ...

(as recorded by

Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of import ...

), established most of the northern constellations in international use today. The constellations along the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...

are called the

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The p ...

. 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. In 1922, the International Astronomical Union adopted three-letter abbreviations for 89 constellations, the modern list of 88 plus Argo. After this,

Eugène Joseph Delporte Eugène Joseph Delporte (10 January 1882 – 19 October 1955) was a Belgian astronomer born in Genappe. He discovered a total of sixty-six asteroids. Notable discoveries include 1221 Amor (which lent its name to the Amor asteroids) and ...

drew up boundaries for each of the 88 constellations so that every point in the sky belonged to one constellation.

History

Some constellations are no longer recognized by the IAU, but may appear in older star charts and other references. Most notable is

Argo Navis Argo Navis (the Ship Argo), or simply Argo, is one of the 48 Ptolemy's constellations, now a grouping of three IAU constellations. It is formerly a single large constellation in the southern sky. The genitive is "Argus Navis", abbreviated "Arg". ...

, 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 Puppis is a constellation in the southern sky. Puppis, the Latin translation of " poop deck", was originally part of an over-large constellation Argo Navis (the ship of Jason and the Argonauts), which centuries after its initial description, w ...

, and

Vela Vela or Velas may refer to: Astronomy * Vela (constellation), a constellation in the southern sky (the Sails) ** Vela (Chinese astronomy) ** Vela Pulsar ** Vela X-1, a pulsing, eclipsing high-mass X-ray binary system Places * Vela Bluff, Antarc ...

Modern constellations

The 88 constellations depict 42 animals, 29 inanimate objects and 17 humans or mythological characters.

Abbreviations

Each IAU constellation has an official 3-letter abbreviation based on the

genitive In grammar, the genitive case ( abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can ...

form of the constellation name. The majority of the abbreviations are just the first three letters of the constellation name, with the first character capitalised: ''Ori'' for ''Orion'', ''Ara'' for ''Ara/Arae'', ''Com'' for ''Coma Berenices''. In some cases, the abbreviation is from the genitive form without 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 ''Sagittarius'', abbreviated ''Sgr''). In other cases, to unambiguously identify the constellation, such as where the name and its genitive differ in the first three letters, other letters beyond the initial three are used: ''Aps'' for ''Apus/Apodis'', ''CrA'' for ''Corona Australis'', ''CrB'' for ''Corona Borealis'', ''Crv'' for ''Corvus''. (''Crater'' is abbreviated ''Crt'' to prevent confusion with ''CrA''.) 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'').

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 Latin phonology continually evolved over the centuries, making it difficult for speakers in one era to know how Latin was spoken before then. A given phoneme may be represented by different letters in different periods. This article deals primar ...

Asterisms

Various other unofficial patterns exist alongside the constellations. These are known as "asterisms". Examples include the

Big Dipper The Big Dipper ( US, Canada) or the Plough ( UK, Ireland) is a large asterism consisting of seven bright stars of the constellation Ursa Major; six of them are of second magnitude and one, Megrez (δ), of third magnitude. Four define a "bowl ...

/Plough and the Northern Cross. Some ancient asterisms, for example

Coma Berenices Coma Berenices is an ancient asterism in the northern sky, which has been defined as one of the 88 modern constellations. It is in the direction of the fourth galactic quadrant, between Leo and Boötes, and it is visible in both hemisphe ...

Serpens Serpens ( grc, , , the Serpent) is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International ...

, and portions of

, are now officially constellations.

Notes

References

External links

* http://www.ianridpath.com/constellations1.htm – Ian Ridpath's list of constellations. * http://www.ianridpath.com/startales/contents.htm – Ian Ridpath's ''Star Tales''. * http://cdsarc.u-strasbg.fr/viz-bin/Cat?cat=VI/49 – CDS's archive of constellation boundaries. The text file constbnd.dat gives the 1875.0 coordinates of the vertices of the constellation regions, together with the constellations adjacent to each boundary segment. {{DEFAULTSORT:List Of Constellations * * IAU constellations