In contemporary

astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

, 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 first constellations were likely defin ...

are recognized by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

(IAU). Each constellation is a region of the

sky The sky is an unobstructed view upward from the planetary surface, surface of the Earth. It includes the atmosphere of Earth, atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from ...

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 equinox (celestial coordinates), March equinox to the (hour circle of the) point in questio ...

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. The declination angle is measured north (positive) or ...

, together covering the entire

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, ...

. Their boundaries were officially adopted by the International Astronomical Union in 1928 and published in 1930. The ancient Mesopotamians and later the

Greeks Greeks or Hellenes (; , ) are an ethnic group and nation native to Greece, Greek Cypriots, Cyprus, Greeks in Albania, southern Albania, Greeks in Turkey#History, Anatolia, parts of Greeks in Italy, Italy and Egyptian Greeks, Egypt, and to a l ...

established most of the northern constellations in international use today, listed by the Roman-Egyptian astronomer

Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...

. The constellations along the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

are called the

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this 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. After this, Eugène Joseph Delporte drew up boundaries for each of the 88 constellations so that every point in the sky belonged to one constellation. When astronomers say that an object lies in a particular constellation, they mean that it is 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. Most notable 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.

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

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. As the genitive is similar to the base name, the majority of the abbreviations are just the first three letters of the constellation name: ''Ori'' for ''Orion/Orionis'', ''Ara'' for ''Ara/Arae'', and ''Com'' for ''Coma Berenices/Comae Berenices''. In some 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 ''Sagittarius'', abbreviated ''Sgr''). Some abbreviations use letters beyond the initial three to unambiguously identify the constellation (for example when the name and its genitive differ in the first three letters): ''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''). 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. 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 Latin phonology is the system of sounds used in various kinds of Latin. This article largely deals with what features can be deduced for Classical Latin as it was spoken by the educated from the late Roman Republic to the early Roman Empire, Empir ...

Asterisms

Various other unofficial patterns exist alongside the constellations. These are known as "asterisms". Some are part of one larger constellation while others consists of stars in two adjoining constellations. Examples include the

Big Dipper The Big Dipper (American English, US, Canadian English, Canada) or the Plough (British English, UK, Hiberno-English, Ireland) is an asterism (astronomy), asterism consisting of seven bright stars of the constellation Ursa Major; six of them ar ...

/Plough in

Ursa Major Ursa Major, also known as the Great Bear, is a constellation in the Northern Sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear", referring to and contrasting it with nearby Ursa M ...

; the Teapot in Sagittarius; the Square of Pegasus in Pegasus and Andromeda; and the False Cross in Carina and Vela.

Notes

References

External links

The Constellations 1
– Ian Ridpath's list of constellations.
Ian Ridpath's Star Tales: Constellation Mythology and History
– Ian Ridpath's ''Star Tales''.
VizieR
– 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