Saros (astronomy)

Length of time after which an eclipse repeats

In astronomy, the saros is a length of time covering exactly 223 synodic months (18 years 11 days and 8 hours), nearly 242 draconic months, and nearly 239 anomalistic months. Arising naturally due to synchronization between lunar phase, nodal precession, and apsidal precession, it can be used to predict eclipses of the Sun and Moon. One saros period after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, a near straight line, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle.

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