25. Saros Innards

In addition to tracking a Saros cycle from one eclipse to the next, the Babylonians worked out the internal structure of the period. The 18 years interval, or more precisely 223 months, allows for exactly 38 eclipses possibilities, 33 spaced 6 months apart and 5 separated by 5 months.

The Babylonians organized this scheme in tables of Saros cycles that begin as early as 747 BC. They continued mapping the Saros scheme until the 1st century AD.