original_query: What is the relationship between synodic months and draconic months in terms of the occurrence of eclipses?
query: What is the relationship between synodic months and draconic months in terms of the occurrence of eclipses?
answer: Eclipses occur when the new or full moon is near a node of the Moon's orbit.  The synodic month (time between new moons) and the draconic month (time between the Moon's returns to a node) are incommensurate, meaning their ratio isn't a whole number.  Eclipse cycles are based on finding fractions that approximate this ratio, representing periods where a new or full moon will again be near a node, allowing for repeated eclipses. The Saros cycle (223 synodic months ≈ 242 draconic months) is a prime example.