saros(redirected from Saros cycle)
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[Gr.,=failing], in astronomy, partial or total obscuring of one celestial body by the shadow of another. Best known are the lunar eclipses, which occur when the earth blocks the sun's light from the moon, and solar eclipses, occurring when the moon blocks the sun's light
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saros(sair -os) The period of 6585.32 days (about 18 years) that elapses before a particular sequence of solar and lunar eclipses can recur in the same order and with approximately the same time intervals. Following such a period, the Earth, Sun, Moon, and nodes of the Moon's orbit return to about the same relative positions: the period is equal to 223 synodic months and is almost equal to 19 eclipse years (6585.78 days). An eclipse repeated after one saros occurs 0.32 days later and hence 115°W of its predecessor. The saros was known in ancient times.
the period over which solar and lunar eclipses are repeated in the same sequence as a result of the repetition of the relative positions of the sun, the moon, and the nodes of the lunar orbit on the celestial sphere. The saros was known in Egypt and Greece several centuries before the Common Era. It is approximately equal to 6,585 1/3 days, that is, 18 years and 10 1/3 or 11 1/3 days, depending on the number of leap years in the period under consideration. During one saros there are 43 solar eclipses (12 total, two mixed annular and total, 14 annular, and 15 partial) and 28 lunar eclipses; for various reasons, the number of eclipses in different periods may vary somewhat. Eclipses can be predicted approximately on the basis of the saros, but without an exact indication of the areas of visibility or times of onset.