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.