In contemporary astronomy, the sky is divided into 88 regions called constellations, generally based on the asterisms (which are also called “constellations”) of Greek and Roman mythology. The number of 88, along with the contemporary scientific notion of “constellation”, was convention in 1922 by the International Astronomical Union in order to establish a universal pattern for professional astronomers, who defined constellations from then on as regions of the sky separated by arcs of right ascensions and declinations and grouped by asterisms of their historically most important stars, which cover the entire celestial sphere. The constellations along the ecliptic are called the zodiac.

The ancient Sumerians, and later the Greeks (as recorded by Ptolemy), established most of the northern constellations in international use today. When explorers mapped the stars of the southern skies, European and American astronomers proposed new constellations for that region, as well as ones to fill gaps between the traditional constellations. Not all of these proposals caught on, but in 1922, the International Astronomical Union (IAU) adopted the modern list of 88 constellations. After this, Eugène Joseph Delporte drew up precise boundaries for each constellation, so that every point in the sky belonged to exactly one constellation.

History

Constellation

Some constellations are no longer recognized by the International Astronomical Union but may appear in older star charts and other references. Most notable is Argo Navis, which was one of Ptolemy’s original 48 constellations.
a constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices. The 88 modern constellations are defined regions of the sky together covering the entire celestial sphere.

Origins for the earliest constellations likely goes back to prehistory, whose now unknown creators collectively used them to relate important stories of either their beliefs, experiences, creation or mythology. As such, different cultures and countries often adopted their own set of constellations outlines, some that persisted into the early 20th century. Adoption of numerous constellations has significantly changed throughout the centuries. Many have varied in size or shape, while some became popular then dropped into obscurity. Others were traditionally used only by various cultures or single nations.

The traditional Western constellations are the 48 Greek classical patterns, as stated in both Aratus’ work Phenomena or Ptolemy’s Almagest, though their existence probably predates these constellation names by several centuries. Newer constellations in the far Southern Sky were added much later since the 15th century until the mid-18th century when European explorers began traveling to the Southern Hemisphere. Twelve important constellations are assigned to the zodiac (where the Sun, Moon, and planets all lie), which straddles the ecliptic. The origins of the zodiac probably date back into prehistory, whose astrological divisions became prominent c. 400 BC within Babylonian or Chaldean astronomy.

In 1928, the International Astronomical Union (IAU) ratified and recognized 88 modern constellations, with contiguous boundaries defined by right ascension and declination. Therefore, any given point in a celestial coordinate system lies in one of the modern constellations. Some astronomical naming systems give the constellation where a given celestial object is found along with a designation in order to convey an approximate idea of its location in the sky. e.g. The Flamsteed designation for bright stars consists of a number and the genitive form of the constellation name.

Former constellations

Former constellations are old historical Western constellations that for various reasons are no longer recognized or adopted as official constellations by the International Astronomical Union (IAU). Prior to 1930, many of these defunct constellations were traditionally identified by one or more countries or cultures. Some only lasted several decades but others continued over many centuries. All are now only recognized for having classical or historical value. Many former constellations have had complex Latinised names assigned as objects, people, or as mythological or zoological creatures. Others with unwieldy names were foreshortened for the sake of practical convenience. e.g. Scutum Sobiescianum reduced to Scutum, Mons Mensae to Mensa or Apparatus Sculptoris to Sculptor.

Some of the northern sky’s former constellations were often placed in the less populated stellar regions between the traditional brighter constellations just to fill any unassigned gaps. In the southern skies, new constellations were often created from about the 15th Century by voyagers who began journeying south of the equator. European countries like England, France, the Netherlands, German or Italian states, etc., often supported and popularised their constellation outlines. In some cases, differing constellations occupied areas using the same shared stars. Most of these former constellations can often be found mentioned in older books, star charts or star catalogs.

Standardisation of all the modern eighty-eight constellations names and boundaries was finally made by Eugene Delporte for the IAU in 1930, under a ratified international agreement, successfully removing any possible astronomical ambiguities between the nations. Nearly all former or defunct constellations mostly differ in their designated boundaries inasmuch as they have outlines that do not follow the exacting defined lines of right ascension and declination.

Modern Constellations

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

Abbreviations

Each of the IAU constellations has an official 3 letter abbreviation. They are actually abbreviations of the genitive form of the constellation names, so some letters appearing in the abbreviation may come from the genitive form without appearing in the base name (as in Sge for Sagitta/Sagittae, to avoid confusion with Sagittarius, abbreviated Sgr).

The majority of the abbreviations are just the first three letters of the constellation, with the first character capitalised: Ori for Orion, Ara for Ara/Arae, Com for Coma Berenices. In cases where this would not unambiguously identify the constellation, or 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.

The abbreviations are unambiguous, with two exceptions. 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.

ConstellationOriginMeaningBrightest star
Andromedaancient (Ptolemy)Andromeda (The chained maiden or princess)Alpheratz
Antlia1763, Lacailleair pumpα Antliae
Apus 1603, Uranometria, created by Keyser and de HoutmanBird-of-paradise/Exotic Bird/Extraordinary Birdα Apodis
Aquarius ancient (Ptolemy)water-bearerSadalsuud
Aquila ancient (Ptolemy)eagleAltair
Araancient (Ptolemy)altarβ Arae
Ariesancient (Ptolemy)ramHamal
Auriga ancient (Ptolemy)charioteerCapella
Boötes ancient (Ptolemy)herdsmanArcturus
Caelum1763, Lacaillechisel or graving toolα Caeli
Camelopardalis 1613, Plancius[7]giraffeβ Camelopardalis
Cancer ancient (Ptolemy)crabTarf[8]
Canes Venatici 1690, Firmamentum Sobiescianum, Heveliushunting dogsCor Caroli
Canis Major ancient (Ptolemy)greater dogSirius
Canis Minor ancient (Ptolemy)lesser dogProcyon
Capricornus ancient (Ptolemy)sea goatDeneb Algedi
Carina 1763, Lacaille, split from Argo NaviskeelCanopus
Cassiopeia ancient (Ptolemy)Cassiopeia (mythological character)Schedar[8]
Centaurus ancient (Ptolemy)centaurRigil Kentaurus[8]
Cepheus ancient (Ptolemy)Cepheus (mythological character)Alderamin
Cetusancient (Ptolemy)sea monster (later interpreted as a whale)Diphda[8]
Chamaeleon 1603, Uranometria, created by Keyser and de Houtmanchameleonα Chamaeleontis
Circinus 1763, Lacaillecompassesα Circini
Columba1592, Plancius, split from Canis MajordovePhact
Coma Berenices 1603, Uranometria, split from LeoBerenice’s hairβ Comae Berenices
Corona Australis[9]ancient (Ptolemy)southern crownMeridiana[8]
Corona Borealis ancient (Ptolemy)northern crownAlphecca
Corvus ancient (Ptolemy)crowGienah
Crater ancient (Ptolemy)cupδ Crateris
Crux 1603, Uranometria, split from Centaurussouthern crossAcrux
Cygnus ancient (Ptolemy)swan or Northern CrossDeneb
Delphinus ancient (Ptolemy)dolphinRotanev
Dorado 1603, Uranometria, created by Keyser and de Houtmandolphinfishα Doradus
Draco ancient (Ptolemy)dragonEltanin[8]
Equuleus ancient (Ptolemy)ponyKitalpha
Eridanusancient (Ptolemy)river Eridanus (mythology)Achernar
Fornax1763, Lacaillechemical furnaceDalim[8]
Gemini ancient (Ptolemy)twinsPollux
Grus 1603, Uranometria, created by Keyser and de HoutmanCraneAlnair
Hercules ancient (Ptolemy)Hercules (mythological character)Kornephoros
Horologium1763, Lacaillependulum clockα Horologii
Hydra ancient (Ptolemy)Hydra (mythological creature)Alphard
Hydrus1603, Uranometria, created by Keyser and de Houtmanlesser water snakeβ Hydri
Indus 1603, Uranometria, created by Keyser and de HoutmanIndian (of unspecified type)α Indi
Lacerta1690, Firmamentum Sobiescianum, Heveliuslizardα Lacertae
Leoancient (Ptolemy)lionRegulus
Leo Minor1690, Firmamentum Sobiescianum, Heveliuslesser lionPraecipua
Lepus ancient (Ptolemy)hareArneb
Libra ancient (Ptolemy)balanceZubeneschamali[8]
Lupus ancient (Ptolemy)wolfα Lupi
Lynx 1690, Firmamentum Sobiescianum, Heveliuslynxα Lyncis
Lyra ancient (Ptolemy)lyre / harpVega
Mensa1763, LacailleTable Mountain (South Africa)α Mensae
Microscopium1763, Lacaillemicroscopeγ Microscopii
Monoceros1613, Planciusunicornβ Monocerotis
Musca1603, Uranometria, created by Keyser and de Houtmanflyα Muscae
Norma 1763, Lacaillecarpenter’s levelγ2 Normae
Octans1763, Lacailleoctant (instrument)ν Octantis
Ophiuchus ancient (Ptolemy)serpent-bearerRasalhague
Orion ancient (Ptolemy)Orion (mythological character)Rigel
Pavo 1603, Uranometria, created by Keyser and de HoutmanpeacockPeacock
Pegasusancient (Ptolemy)Pegasus (mythological winged horse)Enif
Perseus ancient (Ptolemy)Perseus (mythological character)Mirfak
Phoenix1603, Uranometria, created by Keyser and de HoutmanphoenixAnkaa
Pictor 1763, Lacailleeaselα Pictoris
Piscesancient (Ptolemy)fishesAlpherg
Piscis Austrinus ancient (Ptolemy)southern fishFomalhaut
Puppis1763, Lacaille, split from Argo Navispoop deckNaos
Pyxis 1763, Lacaillemariner’s compassα Pyxidis
Reticulum 1763, Lacailleeyepiece graticuleα Reticuli
Sagittaancient (Ptolemy)arrowγ Sagittae
Sagittariusancient (Ptolemy)archerKaus Australis
Scorpiusancient (Ptolemy)scorpionAntares
Sculptor1763, Lacaillesculptorα Sculptoris
Scutum1690, Firmamentum Sobiescianum, Heveliusshield (of Sobieski)α Scuti
Serpens[11]ancient (Ptolemy)snakeUnukalhai
Sextans 1690, Firmamentum Sobiescianum, Heveliussextantα Sextantis
Taurus ancient (Ptolemy)bullAldebaran
Telescopium 1763, Lacailletelescopeα Telescopii
Triangulumancient (Ptolemy)triangleβ Trianguli
Triangulum Australe1603 Uranometria, created by Keyser and de Houtmansouthern triangleAtria
Tucana 1603 Uranometria, created by Keyser and de Houtmantoucanα Tucanae
Ursa Major ancient (Ptolemy)great bearAlioth
Ursa Minor ancient (Ptolemy)lesser bearPolaris
Vela 1763, Lacaille, split from Argo Navissailsγ2 Velorum
Virgo ancient (Ptolemy)virgin or maidenSpica
Volans1603, Uranometria, created by Keyser and de Houtmanflying fishβ Volantis
Vulpecula1690, Firmamentum Sobiescianum, HeveliusfoxAnser

Asterisms

Various other unofficial patterns exist alongside the constellations. These are known as “asterisms”. Examples include the Big Dipper/Plough and the Northern Cross. Some ancient asterisms, for example, Coma Berenices, Serpens, and portions of Argo Navis are now officially constellations.

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