Exactly 223 synodic months after an eclipse, a near similar eclipse will occur at the same place in the zodiac, a fact that has been known for more than two millennia. These two nearly identical eclipses occurring 18 years apart are said to belong to the same saros cycle (a saros being the time interval between two nearly identical eclipses). If you consider the chain of eclipses separated by 223 synodic months (a saros), they are said to belong to the same saros cycle (a Saros cycle can be about solar or lunar eclipses).

Every lunar and solar eclipses belong to a Saros cycle that spans throughout more than a millennium. At the very beginning of a Saros cycle, the sun, moon and earth are poorly aligned, resulting in partial eclipses. As time progresses, the Saros eclipses become more spectacular as the sun, moon, earth alignment improves and eclipses become total. Intensity reaches its climax when the three bodies are perfectly aligned. This is what I define as the culmination of the Saros cycle. Then, the perfect alignment relative to one Saros cycle gradually vanishes, its eclipses become partial again, then cease. This process, the rise, culmination and retraction of a Saros cycle spans over a millennium of years, and generally comprises 71-73 eclipses (figure 1).