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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Constellation | 4/4 | https://en.wikipedia.org/wiki/Constellation | reference | science, encyclopedia | 2026-05-05T13:31:57.150168+00:00 | kb-cron |
A list of 88 constellations was produced for the IAU in 1922. It is roughly based on the traditional Greek constellations listed by Ptolemy in his Almagest in the 2nd century and Aratus' work Phenomena, with early modern modifications and additions (most importantly introducing constellations covering the parts of the southern sky unknown to Ptolemy) by Petrus Plancius (1592, 1597/98 and 1613), Johannes Hevelius (1690) and Nicolas Louis de Lacaille (1763), who introduced fourteen new constellations. Lacaille studied the stars of the southern hemisphere from 1751 until 1752 from the Cape of Good Hope, when he was said to have observed more than 10,000 stars using a refracting telescope with an aperture of 0.5 inches (13 mm). In 1922, Henry Norris Russell produced a list of 88 constellations with three-letter abbreviations for them. However, these constellations did not have clear borders between them. In 1928, the IAU formally accepted the 88 modern constellations, with contiguous boundaries along vertical and horizontal lines of right ascension and declination developed by Eugene Delporte that, together, cover the entire celestial sphere; this list was finally published in 1930. Where possible, these modern constellations usually share the names of their Graeco-Roman predecessors, such as Orion, Leo, or Scorpius. The aim of this system is area-mapping, i.e. the division of the celestial sphere into contiguous fields. Of the 88 modern constellations, 36 lie predominantly in the northern sky, and the other 52 predominantly in the southern.
The boundaries developed by Delporte used data that originated back to epoch B1875.0, which was when Benjamin A. Gould first made his proposal to designate boundaries for the celestial sphere, a suggestion on which Delporte based his work. The consequence of this early date is that because of the precession of the equinoxes, the borders on a modern star map, such as epoch J2000, are already somewhat skewed and no longer perfectly vertical or horizontal. This effect will increase over the years and centuries to come.
=== Symbols ===
The constellations have no official symbols, though those of the ecliptic may take the signs of the zodiac. Symbols for the other modern constellations, as well as older ones that still occur in modern nomenclature, have occasionally been published.
== Dark cloud constellations ==
The Great Rift, a series of dark patches in the Milky Way, is most visible in the southern sky. Some cultures have discerned shapes in these patches. Members of the Inca civilization identified various dark areas or dark nebulae in the Milky Way as animals and associated their appearance with the seasonal rains. Australian Aboriginal astronomy also describes dark cloud constellations, the most famous being the "emu in the sky" whose head is formed by the Coalsack, a dark nebula, instead of the stars.
=== List of dark cloud constellations ===
Great Rift (astronomy) Cygnus Rift Serpens–Aquila Rift Dark Horse (astronomy) Rho Ophiuchi cloud complex Emu in the sky
== See also == Celestial cartography Constellation family Former constellations Lists of stars by constellation Constellations listed by Johannes Hevelius Constellations listed by Lacaille Constellations listed by Petrus Plancius Constellations listed by Ptolemy
== References == Footnotes
Citations
== Further reading ==
=== Mythology, lore, history, and archaeoastronomy ===
=== Atlases and celestial maps ===
=== Catalogs ===
== External links ==
IAU: The Constellations, including high quality maps. Atlascoelestis, di Felice Stoppa. Celestia free 3D realtime space-simulation (OpenGL) Stellarium realtime sky rendering program (OpenGL) Strasbourg Astronomical Data Center Files on official IAU constellation boundaries Studies of Occidental Constellations and Star Names to the Classical Period: An Annotated Bibliography Table of IAU Constellations Online Text: Hyginus, Astronomica translated by Mary Grant Greco-Roman constellation myths Neave Planetarium Adobe Flash interactive web browser planetarium and stardome with realistic movement of stars and the planets. Audio – Cain/Gay (2009) Astronomy Cast Constellations The Greek Star-Map short essay by Gavin White Bucur, Doina (2022). "The network signature of constellation line figures". PLOS ONE. 17 (7) e0272270. arXiv:2110.12329. Bibcode:2022PLoSO..1772270B. doi:10.1371/journal.pone.0272270. PMC 9333327. PMID 35901190.