Solar and Lunar Eclipses 2016, Astrology Calendar - Astro-Seek.com The periodicity and recurrence of solar and lunar eclipses is governed by the Saros cycle. Saros cycle is a period of approximately 6,585.3 days (18 years 11 days 8 hours). When two eclipses are separated by a period of one Saros, they share a very similar geometry.