A period of approximately 54 years and 33 days (19,756 days), equal to three Saros cycles. While a single Saros cycle (~18 years 11 days) produces eclipses of similar type and magnitude, each recurrence shifts westward geographically. The exeligmos nearly eliminates this drift, causing eclipses to repeat at almost the same geographic location with comparable magnitude and type. Discovered by ancient Greek astronomers and utilized by Hipparchus and Ptolemy, it serves as a fundamental unit in mundane astrology for correlating long-term eclipse series (Saros families) with historical events.