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This article is about the star grouping. For other uses, see Constellation (disambiguation).
The constellation Orion is one of the most recognizable in the night sky. The name is associated with the region of the star map marked in yellow, as well as with the pattern of stars within this area, marked in green.

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. Historically, the term was also used to refer to a perceived pattern formed by prominent stars within apparent proximity to one another, and this practice is still common today.

Definition

In colloquial usage, a constellation is a group of celestial bodies, usually stars, which appear to form a pattern in the sky. Astronomers today still utilize the term, though the current system focuses primarily on constellations as grid-like segments of the celestial sphere rather than as patterns. A star-pattern that is not officially classed as a constellation is referred to as an asterism. One famous example is the asterism known as the Big Dipper, a term unused by the International Astronomical Union (IAU) as the stars are considered part of the larger constellation of Ursa Major.

In 1922, Henry Norris Russell aided the IAU in dividing the celestial sphere into 88 official constellations.[1] Typically, these modern constellations share the names of their Graeco-Roman predecessors, such as Orion, Leo and Scorpius. While such celestial formations were originally linked to a mythical event, creature or person, the categorization of the night sky into recognizable patterns was important in early land and naval navigation prior to the invention of the compass during the Age of Discovery. With the technical advancement of astronomy, it became important to move from a pattern-based system of constellations to one based on area-mapping, which led to several historic formations becoming obsolete.[2]

Boundaries

In 1930, the boundaries between the 88 official constellations were devised by Eugène Delporte along vertical and horizontal lines of right ascension and declination, from which 37 belong to northern hemisphere and 51 to southern hemisphere. However, the data he used originated back to epoch B1875.0, which was when Benjamin A. Gould first made the proposal to designate boundaries for the celestial sphere, a suggestion upon which Delporte would base his work. The consequence of this early date is that due to 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.

Proximity

The stars within a constellation rarely have any substantial astrophysical relationship to each other, and their apparent proximity when viewed from Earth disguises the fact that they typically lie light years apart. However, there are some exceptions: the constellation of Ursa Major is almost entirely constituted by stars approximate to one another, a phenomenon known as the Ursa Major moving group.

History

Further information: Obsolete constellations

Babylonian

See also: Babylonian star catalogues

The oldest known catalogues of stars and constellations are from Old Babylonian astronomy, beginning in the Middle Bronze Age. The numerous Sumerian names in these catalogues suggest that they build on older, but otherwise unattested, Sumerian traditions of the Early Bronze Age. The classical Zodiac is a product of a revision of the Old Babylonian system in later Neo-Babylonian astronomy (7th century BC).

Graeco-Roman

The first ancient Greek works which dealt with the constellations were books of star myths. The oldest of these was a poem composed by Hesiod in or around the eighth century BC, of which only fragments survive.

Aratus in the 3rd century BC compiled a verse setting of the otherwise lost catalogue of constellations of Eudoxus of Cnidus (4th century BC). Eudoxus was instrumental in the reception of the older Babylonian star catalogues in ancient Greek astronomy.

The most complete existing works dealing with the mythical origins of the constellations are by the Hellenistic writer termed pseudo-Eratosthenes and an early Roman writer styled pseudo-Hyginus. In the 2nd century AD, the Greek astronomer Ptolemy described the constellations in great detail in his influential work the Almagest.

Chinese

Main article: Chinese constellation

Chinese constellations are different from the Western constellations due to the independent development of ancient Chinese astronomy. One difference is that the Chinese counterpart of the 12 western zodiac constellations is the 28 "Xiu" (宿) or "mansions" (a literal translation).

Indian

See also: Jyotiṣa

In Hindu astrology, the 12 zodiac constellations were adopted from the Greeks in the Hellenistic era. The twelve zodiacal constellations are divided into 27 Nakshatras, or lunar houses.

Dark cloud constellations

The "Emu in the sky," a constellation defined by dark clouds rather than the stars. A western interpretation would recognise Crux (the Southern Cross) above the emu's head and Scorpius on the left. The head of the emu is the Coalsack.

More visible and striking in the southern hemisphere than in the northern, dark patches in the Milky Way vividly stand out in Earth conditions when the Milky Way central region casts noticeable shadows on the ground. Some cultures have discerned shapes in these patches and have given names to these "dark cloud constellations." 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.[3] Australian Aboriginal astronomy also describes dark cloud constellations, the most famous being the "emu in the sky" whose head is formed by the Coalsack.

See also

Notes

  1. ^ "The original names and abbreviations for constellations from 1922". Retrieved 2010-01-31.
  2. ^ "The IAU on constellations". Retrieved 2010-01-31.
  3. ^ The Incan View of the Night Sky

Further reading

Mythology, lore, history, and archaeoastronomy

  • Allen, Richard Hinckley. (1899) Star-Names And Their Meanings, G. E. Stechert, New York, New York, U.S.A., hardcover; reprint 1963 as Star Names: Their Lore and Meaning, Dover Publications, Inc., Mineola, New York, U.S.A., ISBN 978-0486210797 softcover.
  • Olcott, William Tyler. (1911); Star Lore of All Ages, G. P. Putnam's Sons, New York, New York, U.S.A., hardcover; reprint 2004 as Star Lore: Myths, Legends, and Facts, Dover Publications, Inc., Mineola, New York, U.S.A., ISBN 978-0486435817 softcover.
  • Kelley, David H. and Milone, Eugene F. (2004) Exploring Ancient Skies: An Encyclopedic Survey of Archaeoastronomy, Springer, ISBN 978-0-387-95310-6 hardcover.
  • Ridpath, Ian. (1989) Star Tales, Lutterworth Press, ISBN 0718826957 hardcover.
  • Staal, Julius D. W. (1988) The New Patterns in the Sky: Myths and Legends of the Stars, McDonald & Woodward Publishing Co., ISBN 0939923106 hardcover, ISBN 0939923041 softcover.
  • White, Gavin. (2008) Babylonian Star-lore, Solaria Publications, ISBN 9780955903700 softcover.

Atlases and celestial maps

General & Nonspecialized – Entire Celestial Heavens:

  • Becvar, Antonin. Atlas Coeli. Published as Atlas of the Heavens, Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A.; with coordinate grid transparency overlay.
  • Norton, Arthur Philip. (1910) Norton's Star Atlas, 20th Edition 2003 as Norton's Star Atlas and Reference Handbook, edited by Ridpath, Ian, Pi Press, ISBN 978-0-13-145164-3, hardcover.
  • National Geographic Society. (1957, 1970, 2001, 2007) The Heavens (1970), Cartographic Division of the National Geographic Society (NGS), Washington, D.C., U.S.A., two sided large map chart depicting the constellations of the heavens; as special supplement to the August 1970 issue of National Geographic. Forerunner map as A Map of The Heavens, as special supplement to the December 1957 issue. Current version 2001 (Tirion), with 2007 reprint.
  • Sinnott, Roger W. and Perryman, Michael A.C. (1997) Millennium Star Atlas, Epoch 2000.0, Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A., and European Space Agency (ESA), ESTEC, Noordwijk, The Netherlands. Subtitle: "An All-Sky Atlas Comprising One Million Stars to Visual Magnitude Eleven from the Hipparcos and Tycho Catalogues and Ten Thousand Nonstellar Objects". 3 volumes, hardcover, in hardcover slipcase, set ISBN 0-933346-84-0. Vol. 1, 0–8 Hours (Right Ascension), ISBN 0-933346-81-6 hardcover; Vol. 2, 8–16 Hours, ISBN 0-933346-82-4 hardcover; Vol. 3, 16–24 Hours, ISBN 0-933346-83-2 hardcover. Softcover version available. Supplemental separate purchasable coordinate grid transparent overlays.
  • Tirion, Wil; et al. (1987) Uranometria 2000.0, Willmann-Bell, Inc., Richmond, Virginia, U.S.A., 3 volumes, hardcover. Vol. 1 (1987): "The Northern Hemisphere to −6o", by Wil Tirion, Barry Rappaport, and George Lovi, ISBN 0-943396-14-X hardcover, printed boards (blue). Vol. 2 (1988): "The Southern Hemisphere to +6o", by Wil Tirion, Barry Rappaport and George Lovi, ISBN 0-943396-15-8 hardcover, printed boards (red). Vol. 3 (1993) as a separate added work: The Deep Sky Field Guide to Uranometria 2000.0, by Murray Cragin, James Lucyk, and Barry Rappaport, ISBN 0-943396-38-7 hardcover, printed boards (gray). 2nd Edition 2001 (black or dark background) as collective set of 3 volumes – Vol. 1: Uranometria 2000.0 Deep Sky Atlas, by Wil Tirion, Barry Rappaport, and Will Remaklus, ISBN 978-0-943396-71-2 hardcover, printed boards (blue edging); Vol. 2: Uranometria 2000.0 Deep Sky Atlas, by Wil Tirion, Barry Rappaport, and Will Remaklus, ISBN 978-0-943396-72-9 hardcover, printed boards (green edging); Vol. 3: Uranometria 2000.0 Deep Sky Field Guide by Murray Cragin and Emil Bonanno, ISBN 978-0-943396-73-6, hardcover, printed boards (teal green).
  • Tirion, Wil and Sinnott, Roger W. (1998) Sky Atlas 2000.0, various editions. 2nd Deluxe Edition, Cambridge University Press, Cambridge, England (U.K.).

Northern Celestial Hemisphere & North Circumpolar Region:

  • Becvar, Antonin. (1962) Atlas Borealis 1950.0, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Praha, Czechoslovakia, 1st Edition, elephant folio hardcover, with small transparency overlay coordinate grid square and separate paper magnitude legend ruler. 2nd Edition 1972 and 1978 reprint, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Prague, Czechoslovakia, and Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A., ISBN 0-933346-01-8 oversize folio softcover spiral bound, with transparency overlay coordinate grid ruler.

Equatorial, Ecliptic, & Zodiacal Celestial Sky:

  • Becvar, Antonin. (1958) Atlas Eclipticalis 1950.0, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Praha, Czechoslovakia, 1st Edition, elephant folio hardcover, with small transparency overlay coordinate grid square and separate paper magnitude legend ruler. 2nd Edition 1974, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Prague, Czechoslovakia, and Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A., oversize folio softcover spiral bound, with transparency overlay coordinate grid ruler.

Southern Celestial Hemisphere & South Circumpolar Region:

  • Becvar, Antonin. Atlas Australis 1950.0, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Praha, Czechoslovakia, 1st Edition, elephant folio hardcover, with small transparency overlay coordinate grid square and separate paper magnitude legend ruler. 2nd Edition, Czechoslovak Academy of Sciences (Ceskoslovenske Akademie Ved), Prague, Czechoslovakia, and Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A., oversize folio softcover spiral bound, with transparency overlay coordinate grid ruler.

Catalogs

  • Becvar, Antonin. (1959) Atlas Coeli II Katalog 1950.0, Praha, 1960 Prague. Published 1964 as Atlas of the Heavens - II Catalogue 1950.0, Sky Publishing Corporation, Cambridge, Massachusetts, U.S.A.
  • Hirshfeld, Alan and Sinnott, Roger W. (1982) Sky Catalogue 2000.0, Cambridge University Press and Sky Publishing Corporation, 1st Edition, 2 volumes. LCCN 81017975 both vols., and LCCN 83240310 vol. 1. "Volume 1: Stars to Magnitude 8.0", ISBN 0-521-24710-1 (Cambridge) and 0-933346-35-2 (Sky) hardcover, ISBN 0-933346-34-4 (Sky) softcover. Vol. 2 (1985) - "Volume 2: Double Stars, Variable Stars, and Nonstellar Objects", ISBN 0-521-25818-9 (Cambridge) hardcover, ISBN 0-521-27721-3 (Cambridge) softcover. 2nd Edition (1991) with additional third author Frangois Ochsenbein, 2 volumes, LCCN 91026764. Vol. 1: ISBN 0-521-41743-0 (Cambridge) hardcover (black binding); ISBN 0-521-42736-3 (Cambridge) softcover (red lettering with Hans Vehrenberg astrophoto). Vol. 2 (1999): ISBN 0-521-27721-3 (Cambridge) softcover and 0-933346-38-7 (Sky) softcover - reprint of 1985 edition (blue lettering with Hans Vehrenberg astrophoto).
  • Yale University Observatory. (1908, et al.) Catalogue of Bright Stars, New Haven, Connecticut, U.S.A. Referred to commonly as "Bright Star Catalogue". Various editions with various authors historically, the longest term revising author as (Ellen) Dorrit Hoffleit. 1st Edition 1908. 2nd Edition 1940 by Frank Schlesinger and Louise F. Jenkins. 3rd Edition (1964), 4th Edition, 5th Edition (1991), and 6th Edition (pending posthumous) by Hoffleit.
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