An important lunar periodicity that was probably first observed and named by Babylonian astronomers about two millennia BC, the Saros cycle came down to us through the compilations of Hipparchus and Ptolemy. It was successfully employed to predict a solar eclipse on 28 May 585 BC by Thales of Miletus (q.v.). According to Stephenson (1991) probably every eclipse from about 750 BC to 100 AD was anticipated and recorded on clay tablets, although many have been lost. The Saros length is 18.0303 years or 6585.32 days (223 ‘lunations’ or synodic months), which represents the interval after which either solar or lunar eclipses of the same series are repeated. During this time the relative positions of the Earth, Moon and Sun have returned to almost the same relationships. Long-term changes, however, are still poorly understood (Kopal and Mikhaelov, 1962; Lustig, 1967).
The period is approximately 18 years 10 2/3 d, and because of that 1/3 fraction the following eclipse shifts 120° west in...
This is a preview of subscription content, log in via an institution to check access.
Bibliography
Kopal, Z. and Mikhaelov, Z. K. (eds) (1962) The Moon (Int. Astron. Symp. 14, Pulkovo, 1960). New York: Academic Press.
Lustig, L. K. (1967) Earth—Moon relations, in The Encyclopedia of Atmospheric Sciences and Astrogeology (ed. R. W. Fairbridge). New York: Reinhold Publ. Co., pp. 332–5.
Stephenson, F. R. (1991) The Earth's rotation as documented by historical data, in New Approaches in Geomagnetism and the Earth's Rotation (ed. S. Flodmark). Singapore: World Scientific Publ., pp. 87–113.
Rights and permissions
Copyright information
© 1997 Chapman & Hall
About this entry
Cite this entry
Fairbridge, R.W. (1997). Saros cycle . In: Encyclopedia of Planetary Science. Encyclopedia of Earth Science. Springer, Dordrecht. https://doi.org/10.1007/1-4020-4520-4_350
Download citation
DOI: https://doi.org/10.1007/1-4020-4520-4_350
Publisher Name: Springer, Dordrecht
Print ISBN: 978-0-412-06951-2
Online ISBN: 978-1-4020-4520-2
eBook Packages: Springer Book Archive