Saros

The natural cycle over which sequences of lunar and solar eclipses repeat themselves. The period is 6,585.32 days (approximately 18 years): over this cycle the Earth, Sun and Moon return to the same relative positions. An eclipse in one saros occurs about 8 hours later and 115° of longitude further west in the next cycle. This predictability was known to the Maya as well as to the builders of Stonehenge.

Sa"ros (?), n. [NL., fr. Gr. ] Astron

A Chaldean astronomical period or cycle, the length of which has been variously estimated from 3,600 years to 3,600 days, or a little short of 10 years.

Brande & C.

<-- A length of time (6535.82 days, or 18 years 11.32 days, assuming 4 leap years in that interval), after which the eclipses of the sun repeat their pattern, but are shifted 120° west.. -->

© Webster 1913.