Thursday, March 23, 2006

Ancient Solar Eclipses and Delta-T - LexiLine Journal 402

One of the critical parameters for the chronological dating of ancient civilizations is an assessment of ancient solar eclipses. Unfortunately, alleging a solar eclipse to have occurred anywhere on earth at a given date prior to about 700 BC is fraught with difficulty, since the location of solar eclipses depends very much on Delta-T, the change in the rate of spin of the Earth over time.

Fred Espenak at the NASA Eclipse Home Page

http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/deltaT2.html

has a nice, short article on "Historical Values of Delta T" which is a definite "must read" for anyone interested in the confluence of Astronomy and the History of Civilization.

Espenak's page also has four links to Delta T pages online as follows:
  • Delta T - NASA Eclipse Home Page
  • Delta T - Felix Verbelen (Belgium)
  • Delta-T - Robert van Gent (The Netherlands)
  • Delta T - IERS Rapid Service/Prediction Center
There is good agreement between Espenak's data and the ancient eclipses of Egypt featured on Amir Bey's site (click "Eclipses" at that site), referred to several postings ago on LexiLine.

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