series of eclipses separated by a saros period
The Saros cycle is an eclipse cycle of about 18 years 11 days 8 hours (about 6585⅓ days). A solar eclipse 18 years past will be similar with one 18 years in the future. This is because the Earth, Moon and Sun return to almost the same positions they were at 18 years ago. The first predictions of a solar eclipse using the Saros were made by Ancient Greek philosophers.