Lunar eclipses are related by many different eclipse cycles. The Saros cycle (18 years and 10 days) repeats the most consistently due three coinciding periods, and continue over 70 events (1200+ years). Eclipses are identified by a Saros number and a member index within each series. The lunar year (354 days) and Metonic cycles (19 years) are short period last only 8 to 10 events. The Metonic cycle is equal to one Saros cycle plus one lunar year, and so the two series progress in parallel. The Inex cycle (29 years minus 20 days) can last tens of thousands of years, so long that long perturbations in the moon's path must be taken into account for prediction. Also the eclipse qualities are less inconsistent because the moon is at different significantly positions in its elliptical orbit in sequential events. Similarly for the shorter Tritos cycle (10 years and 31 days), repeats less consistently for the same reason.^{[citation needed]}

Saros series edit

Lunar saros series 132, repeating every 18 years and 11 days, has a total of 71 lunar eclipse events including 44 umbral lunar eclipses (32 partial lunar eclipses and 12 total lunar eclipses).

There are 11 series events between 1901 and 2100, grouped into threes (called an exeligmos), each column with approximately the same viewing longitude on earth.

Half-Saros cycle edit

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).^[6] This lunar eclipse is related to two total solar eclipses of Solar Saros 139.