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constellation




  1. A grouping of stars in the night sky that forms a recognizable pattern, derived from some mythical or pictorial association.


  2. Any of the 88 unequal regions into which the celestial sphere is divided by international agreement.
    Go to list of constellations.

The present constellation boundaries were adopted in 1930 by the International Astronomical Union (IAU) having been drawn up by Eugène Delaporte. They are similar to the rectangular borders of some American states that run exactly north/south or east/west. The constellation boundaries run along lines of declination and right ascension for the epoch 1875 (chosen because this epoch had already been used by Benjamin Gould in defining boundaries for the southern constellations.)

Forty-eight of our present-day constellations were identified by Ptolemy in his great Almagest of the second century AD. Coma Berenices was invented by Gerardus Mercator in 1551 by taking a few stars from Leo. A further 12, in the region around the celestial south pole, were staked out by the Dutch explorers Pieter Keyser and Frederick de Houtman and included on a globe of the sky made by Petrus Plancius in 1598 and then in Johan Bayer's Uranometria star atlas in 1603 (see Bayer's constellations). Jakob Bartsch added three constellations in spaces between existing patterns and is also credited with naming Crux, the Cross, by taking four stars from Ptolemy's original Centaurus. Johannes Hevelius contributed seven more in his star atlas of 1687. Finally, in 1750, during a trip to the Cape of Good Hope, Nicolas de Lacaille penciled in the last 14 of our modern constellations to fill in some star-poor regions between existing groups.

The stars making up a constellation are not actually bound together in close association but just happen to lie in roughly the same direction as seen from the observer's viewpoint. For example, the five brightest stars in the constellation of Cygnus the Swan (comprising an arrangement also known as the Northern Cross) are approximately 74, 270, 410, 750 and 1600 light-years from the Sun. Moreover, the dimmest of the quintet, Gienah (Epsilon Cygni), lies nearest to the Sun while the brightest, Deneb (Alpha Cygni), is the most remote. Were these two stars to exchange places, Deneb, which is intrinsically one of the most luminous stars visible to the naked eye, would outshine Venus in our night sky.

Any future travelers to the stars will quickly grow accustomed to the changing shape of constellations as they cross the interstellar voids. The first groupings to become noticeably distorted from their familiar forms will be those made up largely of nearby stars, such as Cassiopeia (three of the brightest members of which are less than 100 light-years from the Sun) and the Big Dipper (with four stars under 100 light-years away). By contrast, none of the prominent stars in Orion is less than 300 light-years distant and several are between 1,000 and 2,000 light-years from the Sun. Only a very lengthy interstellar voyage would suffice to seriously disturb the Great Hunter's well-known outline.

distances to the stars in Orion
The stars in Orion all look as if they lie at the same distance. Turn the constellation through 90°, however, and the true picture emerges. Credit: ESA

The 88 Modern Constellations
Name Genitive Abbr. Area
(sq. deg.)
Rank Origin* R.A. range (h m) Dec. range (o )
Andromeda Andromedae And 722 19 1 23 00 to 02 40 +21 to +53
Antlia Antliae Ant 239 62 6 09 25 to 11 05 -24 to -40
Apus Apodis Aps 206 67 3 13 50 to 18 05 -67 to -83
Aquarius Aquarii Aqr 980 10 1 20 40 to 00 00 +3 to -24
Aquila Aquilae Aql 652 22 1 19 00 to 20 30 +10 to -10
Ara Arae Ara 237 63 1 16 35 to 18 10 -55 to -68
Aries Arietis Ari 441 39 1 01 40 to 03 30 +10 to +30
Auriga Aurigae Aur 657 21 1 04 40 to 07 30 +28 to +55
Bootes Bootis Boo 907 13 1 13 40 to 15 50 +8 to +55
Caelum Caeli Cae 125 81 6 04 20 to 05 10 -27 to -49
Camelopardalis Camelopardalis Cam 757 18 4 03 10 to 14 30 +52 to +87
Cancer Cancri Cnc 506 31 1 07 50 to 09 20 +7 to +33
Canes Venatici Canum Venaticorum CVn 465 38 5 12 10 to 14 10 +28 to +53
Canis Major Canis Majoris CMa 380 43 1 06 10 to 07 30 -11 to -33
Canis Minor Canis Minoris CMi 183 71 1 07 05 to 08 10 0 to +12
Capricornus Capricorni Cap 414 40 1 20 10 to 22 00 -9 to 27
Carina Carinae Car 494 34 6 06 05 to 11 20 -51 to -75
Cassiopeia Cassiopeiae Cas 598 25 1 23 00 to 03 00 +50 to +60
Centaurus Centauri Cen 1,060 9 1 11 05 to 15 00 -30 to -65
Cepheus Cephei Cep 588 27 1 20 05 to 00 00 +53 to +87
Cetus Ceti Cet 1,231 4 1 00 00 to 03 25 +10 to -25
Chamaeleon Chamaeleontis Cha 132 79 3 07 30 to 13 50 +74 to +83
Circinus Circini Cir 93 85 6 13 45 to 15 25 -54 to -70
Columba Columbae Col 270 54 4 05 05 to 06 40 -27 to -43
Coma Berenices Comae Berenices Com 386 42 2 12 00 to 13 53 +14 to +34
Corona Austrina Coronae Austrinae CrA 128 80 1 18 00 to 19 20 -37 to -45
Corona Borealis Coronae Borealis CrB 179 73 1 15 15 to 16 25 +26 to +40
Corvus Corvi Crv 184 70 1 11 55 to 13 00 -11 to -25
Crater Crateris Crt 282 53 1 10 50 to 11 55 -6 to -25
Crux Crucis Cru 68 88 4 12 00 to 13 00 -56 to -65
Cygnus Cygni Cyg 804 16 1 19 10 to 22 00 +28 to +60
Delphinus Delphini Del 189 69 1 20 10 to 21 05 +2 to +21
Dorado Doradus Dor 179 72 3 03 50 to 06 40 -49 to -85
Draco Draconis Dra 1,083 8 1 10 00 to 20 00 +50 to +80
Equuleus Equulei Equ 72 87 1 20 50 to 21 25 +2 to +13
Eridanus Eridani Eri 1,138 6 1 01 20 to 05 10 0 to -58
Fornax Fornacis For 398 41 6 01 45 to 03 50 -24 to -40
Gemini Geminorum Gem 514 30 1 06 00 to 08 05 +10 to +35
Grus Gruis Gru 366 45 3 21 30 to 23 30 -37 to -57
Hercules Herculis Her 1,225 5 1 15 50 to 19 00 +4 to +50
Horologium Horologii Hor 249 58 6 02 10 to 04 20 -40 to -67
Hydra Hydrae Hya 1,303 1 1 08 05 to 15 00 -22 to -65
Hydrus Hydri Hyi 243 61 3 01 25 to 04 30 -58 to -90
Indus Indi Ind 294 49 3 20 30 to 23 30 -45 to -75
Lacerta Lacertae Lac 201 68 5 21 55 to 22 55 +33 to +57
Leo Leonis Leo 947 12 1 09 20 to 11 55 -6 to +33
Leo Minor Leonis Minoris LMi 232 64 5 09 15 to 11 05 +23 to +42
Lepus Leporis Lep 290 51 1 04 55 to 06 10 -11 to -27
Libra Librae Lib 538 29 1 14 20 to 16 00 0 to -30
Lupus Lupi Lup 334 46 1 14 15 to 16 05 -30 to -55
Lynx Lyncis Lyn 545 28 6 06 20 to 09 40 +34 to +62
Lyra Lyrae Lyr 286 52 1 18 10 to 19 30 +26 to +48
Mensa Mensae Men 153 75 6 03 30 to 07 40 -70 to -85
Microscopium Microscopii Mic 210 66 6 20 25 to 21 25 -28 to -45
Monoceros Monocerotis Mon 482 35 4 06 00 to 08 10 -11 to +12
Musca Muscae Mus 138 77 3 11 20 to 13 50 -64 to -74
Norma Normae Nor 165 74 6 15 25 to 16 35 -42 to -60
Octans Octantis Oct 291 50 6 00 00 to 24 00 -75 to -90
Ophiuchus Ophiuchi Oph 948 11 1 16 00 to 18 40 +14 to -30
Orion Orionis Ori 594 26 1 04 40 to 06 20 -11 to +23
Pavo Pavonis Pav 378 44 3 17 40 to 21 30 -57 to -75
Pegasus Pegasi Peg 1,121 7 1 21 05 to 00 15 +2 to +37
Perseus Persei Per 615 24 1 01 30 to 04 50 +31 to +59
Phoenix Phoenicis Phe 469 37 3 23 20 to 02 25 -40 to -59
Pictor Pictoris Pic 247 59 6 04 35 to 06 55 -43 to -64
Pisces Piscium Psc 889 14 1 22 50 to 02 10 -5 to +34
Piscis Austrinus Piscis Austrini PsA 245 60 1 21 25 to 23 05 -25 to -36
Puppis Puppis Pup 673 20 6 06 00 to 08 30 -12 to -51
Pyxis Pyxidis Pyx 221 65 6 08 25 to 09 30 -17 to -38
Reticulum Reticuli Ret 114 82 6 03 15 to 04 40 +53 to +67
Sagitta Sagittae Sge 80 86 1 18 55 to 20 20 +17 to +22
Sagittarius Sagittarii Sgr 867 15 1 18 00 to 20 25 -12 to -46
Scorpius Scorpii Sco 497 33 1 15 45 to 17 55 -8 to -45
Sculptor Sculptoris Scl 475 36 6 23 05 to 01 45 -25 to -59
Scutum Scuti Sct 109 84 5 18 15 to 18 55 -4 to -16
Serpens Serpentis Ser 637 23 1 15 10 to 16 20 &
17 15 to 18 55
-4 to +20 &
-15 to +6
Sextans Sextantis Sex 314 47 5 09 -- to 10 50 -11 to +7
Taurus Tauri Tau 797 17 1 03 20 to 06 00 -1 to +31
Telescopium Telescopii Tel 252 57 6 18 10 to 20 30 -46 to -57
Triangulum Trianguli Tri 132 78 1 01 30 to 02 50 +26 to +37
Triangulum Australe Trianguli Australis TrA 110 83 3 15 00 to 17 00 -60 to -70
Tucana Tucana Tuc 295 48 3 22 10 to 01 20 +56 to +75
Ursa Major Ursae Majoris UMa 1,280 3 1 08 35 to 14 30 +29 to +73
Ursa Minor Ursae Minoris UMi 256 56 1 00 00 to 24 00 +66 to +90
Vela Velorum Vel 500 32 6 08 00 to 11 05 -40 to -57
Virgo Virginis Vir 1,294 2 1 11 35 to 15 10 -22 to +15
Volans Volantis Vol 141 76 3 06 30 to 09 00 -64 to -75
Vulpecula Vulpeculae Vul 268 55 5 19 00 to 21 30 +20 to +30

*1 = Ptolemy, 2 = Mercator, 3 = Keyser/de Houtman, 4 = Plancius, 5 = Hevelius, 6 = Lacaille