What is the Saros Cycle?

The Saros Cycle is an eclipse cycle with a period of nearly 18 years, 11 days and 8 hours. The earliest discovered historical record of the Saros Cycle is by the Chaldeans (ancient Babylonian astronomers). It is very useful for predicting the times at which nearly identical eclipses of the sun and moon will occur. A complication with the Saros Cycle is that its period is not an integer number of days.