A sequence of lunar or solar eclipses occurring at intervals of one saros. Since there are up to seven eclipses every year, there are more than 80 saros series running concurrently. In any one series, an eclipse will recur at a particular longitude after an interval of three saroses 54 years. However, each succeeding eclipse in the series moves systematically in latitude either north or south from one pole to the other, until the series is completed.