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Encyclopedia > Astronomical chronology

Astronomical chronology, or astronomical dating, is a technical method of dating events or artifacts that are associated with astronomical phenomena. Written records of historical events that include descriptions of astronomical phenomena have done much to clarify the chronology of the Ancient Near East; works of art which depict the configuration of the stars and planets and buildings which are oriented to the rising and setting of celestial bodies at a particular time have all been dated through astronomical calculations. Overview map of the ancient Near East The terms ancient Near East or ancient Orient encompass the early civilizations predating classical antiquity in the region roughly corresponding to that described by the modern term Middle East (Egypt, Iraq, Turkey, Israel, Palestinian Authority, Lebanon, Jordan, Syria), during the time roughly spanning...

Astronomical dating can be a powerful tool for establishing absolute chronologies, but...
it can easily produce precise and impressive looking results based on invalid assumptions –
results so precise and impressive they may not be questioned by scholars in other fields.
—John Steele, "The Use and Abuse of Astronomy in Establishing Absolute Chronologies."

Contents

Dating historical events

The use of descriptions of astronomical phenomena to date historical events began in the sixteenth century, a time of a renewed humanistic interest in history and of increasingly precise astronomical tables.[1] In the cases of unique astronomical events like eclipses, since eclipses are relatively infrequent events, they can be dated to the exact date. When the circumstances are not exact and there are several possible eclipses, one can often use other details such as the month of the eclipse or the position of other stars and planets to identify the specific eclipse.[2]


Astronomical dating, like other forms of historical interpretation, requires care in interpreting the surviving written records. John Steele has proposed three questions that must be asked when dating an event: Does the record refer to an actual astronomical event, or is this merely a modern assumption? If it does refer to an actual astronomical event, is the source reliable? Can the record provide an unambiguous date without making unwarranted assumptions about ancient astronomical observational methods?[3]


Babylonian astronomical diaries provide detailed and unambiguous accounts of the positions of all the visible planets, often in relation to specific stars, that have been used to provide precise dates of events like the defeat of Darius III by Alexander the Great at the Battle of Gaugamela on 1 October 331 BCE and of Alexander's subsequent death on 11 June 323.[4] Darius III or Codomannus (c. ... For the film of the same name, see Alexander the Great (1956 film). ... Combatants Macedon Achaemenid Persia Commanders Alexander the Great Darius III Strength 9,000 peltasts,[1] 31,000 hoplites,[1][2] 7,000 cavalry[2] 1,000,000 total (See Size of Persian army) Casualties 4,000 40,000[3] The Battle of Gaugamela (IPA: ) took place in 331 BC between...


Since the success of this method depends on the reliability of the written sources and the precision of their accounts of astronomical phenomena, attempts to date literary texts astronomically, which may describe astronomical events loosely or even as metaphors, have lead researchers to conclusions that appear precise, but rely on invalid assumptions and are consequently less widely accepted. Thus the attempts to date Vedic texts describing the Pleiades as rising "due East" to about 2300 BCE, which is the time when the Pleiades are "exactly" due East is complicated by the fact that poetic descriptions need not be taken as reflecting precise astronomical observations while precession is a very slow process, which makes only small changes in the azimuth of a star rising in the East.[5]


Dating artifacts

Among the artifacts that can most readily be dated by astronomical techniques are depictions of the positions of the celestial bodies at a particular time. Since the motions of the celestial bodies are all at different periods, it takes many centuries for all the planets plus the Sun and the Moon, to reach the same positions in the signs of the Zodiac. For a configuration accurate to ±15° (that is, within a single sign) the positions of these seven bodies will only return to the same configuration once in about 3700 years. A particular case involved a medieval illuminated manuscript which portrayed the position of these seven celestial bodies on 18 March 816; corresponding to the period when the manuscript was written. This calculation demonstrated that this illustration was not a copy of an earlier classical depiction of the position of the stars.[6] The rapidly moving Moon is the most sensitive indicator for the exact time; if one can estimate the indicated position of the Moon to within a degree, the time of the diagram can be computed to within an hour.[7] ... For other uses, see Zodiac (disambiguation). ... For other uses, see Zodiac (disambiguation). ... In the strictest definition of illuminated manuscript, only manuscripts decorated with gold or silver, like this miniature of Christ in Majesty from the Aberdeen Bestiary (folio 4v), would be considered illuminated. ...


A striking example of this method was an astrological portrait of Sir Christopher Hatton (1540-1591), which depicted the positions of the seven classical planets in the zodiac and noted the computed positions of the planets to the nearest minute of arc. Here the largest source of error in the date was the uncertainty of 16th-century astronomical calculations. The resulting time was about noon of 12 December 1581.[8] Christopher Hatton, c. ...


Dating structures by their orientation

A more controversial archaeoastronomical approach has been used to date structures that are believed to have been oriented on astronomical principles by measuring their orientation and computing the date in the past when a single specified celestial body, whether the Sun or a selected star, rises or sets at the measured azimuth. The astronomer, Norman Lockyer, applied this method to Stonehenge[9] by measuring the orientation of the Stonehenge avenue and comparing it to the position of solstitial sunrise, which changes slowly due to the changing obliquity of the ecliptic. The archaeologist, F. C. Penrose, applied a similar method to ancient Greek Temples, attempting to establish their dates by relating their orientation to the appearance of stars on the horizon, the position of which changes slowly due to the precession of the equinoxes.[10] The sun rising over Stonehenge at the 2005 Summer Solstice. ... Sir Joseph Norman Lockyer or Norman Lockyer (May 17, 1836 – August 16, 1920) was an English scientist and astronomer. ... For other uses, see Stonehenge (disambiguation). ... The Obliquity of the ecliptic is the angle between the plane of the Earths equator and the ecliptic plane in which the Earth rotates around the Sun. ... Precession of the equinoxes refers to the precession of the Earths axis of rotation. ...


The wide variance or these dates from historically accepted ones led the architect and archaeologist, William Bell Dinsmoor, to mistrust dates established by the slowly changing obliquity of the ecliptic or by stellar alignments, which involve an arbitrary selection of a star that rises on the proper azimuth. Instead he proposed a method employing what was already known from historical records concerning the dates of construction of Greek temples, the festivals associated with specific temples, and the nature of the Greek Lunisolar calendar. Since the date of a festival in the Greek lunisolar calendar only recurs on the same date in the solar calendar every eight or nineteen years, Dinsmoor identified a festival connected with a specific temple and was able to determine the exact year near the historically recorded construction date when the Sun rose in alignment with the temple.[11] William Bell Dinsmoor, Sr. ... A lunisolar calendar is a calendar whose date indicates both the moon phase and the time of the solar year. ...


Notes

  1. ^ Anthony Grafton, "Some Uses of Eclipses in Early Modern Chronology," Journal of the History of Ideas, 64 (2003): 213-229.
  2. ^ F. R. Stephenson and J. M. Steele, "Astronomical Dating of Babylonian Texts Describing the Total Solar Eclipse of S.E. 175", Journal for the History of Astronomy, 37 (2006): 55-69.
  3. ^ John M. Steele, "The Use and Abuse of Astronomy in Establishing Ancient Chronologies," Physics in Canada/La Physique au Canada, 59 (2003): 243-8, p. 247.
  4. ^ Jona Lendering, "Astronomical Diaries"
  5. ^ Michael Witzel, "The Pleiades and the Bears viewed from inside the Vedic texts," Electronic Journal of Vedic Studies, 5 (1999), issue 2
  6. ^ Richard Mostert and Marco Mostert, "Using astronomy as an aid to dating manuscripts, The example of the Leiden Aratea planetarium", Quaerendo, 20 (1999): 248-261; see esp. § 6. Reliability of the Dating Method, p. 258.
  7. ^ William D. Stahlman, "Astronomical Dating Applied to a Type of Astrological Illustration," Isis, 47 (1956): 154-160, p. 158.
  8. ^ Arthur Beer, "Astronomical dating of works of art", Vistas in Astronomy, 9 (1967): 177-223.
  9. ^ Norman Lockyer and F. C. Penrose, "An Attempt to Ascertain the Date of the Original Construction of Stonehenge from Its Orientation", Proceedings of the Royal Society of London, 69. (1901 - 1902): 137-147.
  10. ^ F. C. Penrose, "On the Results of an Examination of the Orientations of a Number of Greek Temples with a View to Connect these Angles with the Amplitudes of Certain Stars at the Time the Temples were Founded, and an Endeavour to Derive therefrom the Dates of their Foundation by Consideration of the Changes Produced upon the Right Ascension and Declination of the Stars by the Precession of the Equinoxes", Philosophical Transactions of the Royal Society of London, A, 184 (1893): 805-834.
  11. ^ William Bell Dinsmoor, "Archæology and Astronomy", Proceedings of the American Philosophical Society, 10 (1939): 95-173.

Professor F. Richard Stephenson is an Emeritus Professor at the Physics department at the University of Durham. ... Jona Lendering is a Dutch historian and the author of books on antiquity, Dutch history and modern management. ...

References

  • Neugebaer, Otto. A History of Ancient Mathematical Astronomy, (3 vols). New York: Springer, 1975. Vol. 3, pp. 1071-1076 provides a brief introduction to astronomical chronology.

Bibliography

  • Gingerich, Owen and Barbara Welther. Planetary, Lunar, and Solar Positions, A. D. 1650 to 1805, Memoirs of the American Philosophical Society, 59S. Philadelphia, 1983.
  • Neugebauer, Paul V. Astronomische Chronologie (2 vols). Berlin: De Gruyter, 1929.
  • Steele, John M. "The Use and Abuse of Astronomy in Establishing Absolute Chronologies", Physics in Canada/La Physique au Canada, 59 (2003): 243-248.
  • Tuckerman, Bryant. Planetary, Lunar, and Solar Positions, 601 B.C. to A, D. 1, Memoirs of the American Philosophical Society, 56. Philadelphia, 1962.
  • Tuckerman, Bryant. Planetary, Lunar, and Solar Positions, A. D. 2 to 1649, Memoirs of the American Philosophical Society, 59. Philadelphia, 1964.

External links

  • van Gent, R. H., Astronomical Chronology
Amino acid dating is a technique used to estimate age in a wide variety of situations. ... The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. ... Generally a chronicle (Latin chronica, from Greek Χρόνος) is historical account of facts and events in chronological order. ... Cover of History: Fiction or Science? Chronology volumes 1,2,3 The New Chronology of Anatoly Timofeevich Fomenko is an attempt to rewrite world chronology, based on his conclusion that world chronology as we know it today is fundamentally flawed. ... Periodization is the attempt to categorize or divide time into discrete named blocks. ... A Synchronoptic view is a graphic display of a number of entities as they proceed through time. ... For other uses, see Timeline (disambiguation). ... For the political notion, see Year Zero (political notion). ... Look up Circa on Wiktionary, the free dictionary The Latin word circa, literally meaning about, is often used to describe various dates (often birth and death dates) that are uncertain. ... Floruit (or fl. ...


 
 

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