We currently have 88 constellations recognised by the IAU, but it was not always thus.
The Ancient Greeks had knowledge of only the Northern hemisphere and the stars visible from it. So their constellations did not, for example, include Crux, the Southern Cross, which is only visible from latitudes south of the Equator.
The list of constellations that summarised what tbe Greeks knew about astronomy was compiled by Ptolemy, a Hellenic scholar living in Alexandria in Egypt from 90-168 AD. Known as the Almagest, it contains a star catalogue, which is probably an updated version of a catalogue created by Hipparchus, three centuries earlier.
Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky (only the sky Ptolemy could see).
Argo Navis
Argo Navis is the only constellation from Ptolemy's original list of 48 constellations that is no longer officially recognized.
Due to its large size, it was split into three constellations by Nicolas Louis de Lacaille: Carina (the keel), Puppis (the poop deck), and Vela (the sails). This new version was introduced in the star catalog Coelum Australe Stelliferum in 1763, which was published after de Lacaille's death.
Over the years, a number of constellations were proposed or invented, by various astronomers, which never caught on, and fell into disuse:
Antinous, Apis the bee (renamed Musca), Argo Navis, Cerberus, Custos Messium, Felis, Frederici Honores, Gallus, Globus Aerostaticus, Lochium Funis, Machina Electrica, Malus, Mons Maenalus, Musca Borealis, Noctua, Officina Typographica, Phoenicopterus (an obsolete name for Grus),
Polophylax, Psalterium Georgii, Quadrans Muralis, Ramus Pomifer, River Tigris, Robur Carolinum, Sceptrum Brandenburgicum, Sceptrum et Manus Iustitiae, Solarium, Tarandus vel Rangifer, Taurus Poniatovii, Telescopium Herschelii, Testudo, Triangulum Minor, Turdus Solitarius, Vespa (see second link)
As an example of what happened to these temporary constellations:
Quadrans Muralis
Quadrans Muralis was originally created in 1795, but has since been merged into the constellations Boötes and Ursa Major. However the Quadrantids meteor shower is still named after the former constellation.
In more recent times this list has been added to in order to fill gaps between Ptolemy's patterns. The Greeks considered the sky as including both constellations and dim spaces between. But Renaissance star catalogs by Johann Bayer and John Flamsteed required every star to be in a constellation, and the number of visible stars in a constellation to be manageably small.
The constellations around the South Pole were not observable by the Greeks. Twelve were created by Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman in the sixteenth century and first cataloged by Johann Bayer.
The 12 Constellations created by Pieter Dirkszoon Keyser and Frederick de Houtman between 1595 and 1597 and introduced by Johann Bayer in the 1603 text Uranometria were Apus, Chamaeleon, Dorado, Grus, Hydrus, Indus, Musca, Pavo, Phoenix, Triangulum Australe, Tucana, and Volans,
Several more were created by Nicolas Louis de Lacaille in his posthumous Coelum Australe Stelliferum, published in 1763. The 14 Constellations introduced by Lacaille in 1763 were Antlia, Caelum, Circinus, Fornax, Horologium, Mensa, Microscopium, Norma, Octans, Pictor, Pyxis, Reticulum, Sculptor and Telescopium.
In 1690 Johannes Hevelius introduced 7 new constellations delineated by him in his text Firmamentum Sobiescianum: Canes Venatici, Lacerta, Leo Minor, Lynx, Scutum, Sextans, and Vulpecula.
In 1922, the International Astronomical Union (IAU) (3 years after it was formed) officially adopted the modern list of 88 official constellations. After this, Eugène Delporte drew up precise boundaries for each constellation, so that every point in the sky belonged to exactly one constellation.
The full modern list reads: Andromeda • Antlia • Apus • Aquarius • Aquila • Ara • Aries • Auriga • Boötes • Caelum • Camelopardalis • Cancer • Canes Venatici • Canis Major • Canis Minor • Capricornus • Carina • Cassiopeia • Centaurus • Cepheus • Cetus • Chamaeleon • Circinus • Columba • Coma Berenices • Corona Australis • Corona Borealis • Corvus • Crater • Crux • Cygnus • Delphinus • Dorado • Draco • Equuleus • Eridanus • Fornax • Gemini • Grus • Hercules • Horologium • Hydra • Hydrus • Indus • Lacerta • Leo • Leo Minor • Lepus • Libra • Lupus • Lynx • Lyra • Mensa • Microscopium • Monoceros • Musca • Norma • Octans • Ophiuchus • Orion • Pavo • Pegasus • Perseus • Phoenix • Pictor • Pisces • Piscis Austrinus • Puppis • Pyxis • Reticulum • Sagitta • Sagittarius • Scorpius • Sculptor • Scutum • Serpens • Sextans • Taurus • Telescopium • Triangulum • Triangulum Australe • Tucana • Ursa Major • Ursa Minor • Vela • Virgo • Volans • Vulpecula
NB Constellations are stars that are in the same line of sight as seen from earth. These stars are rarely at a similar distance away from earth as one another, and over thousand of years, the constellations will start to look very different as the stars involved move in all different directions, and this is also affected by the Sun completing an orbit of the Orion Arm of the Milky Way once every 200-225 million years.
2006-10-23 13:45:19
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answer #5
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answered by Anonymous
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