5d: Why don't eclipses take place on an annual basis at least?
The orbital periods of the earth around the sun and the moon around the earth have no common integer divisor. They are incommensurable, as mathematicians say. So the nodes of the lunar have a time shift and do not follow the annual rhythm. Because the earth still rotates about its own axis and this axis is tilted to the ecliptic, the eclipses take place at very different places on Earth.
But throughout many years of observation you can still discover regularities, the so-called Saroscycles. This case is outlined in more detail and can be found at this site (copyright © Ulf Unbehaun).

Read more at:
5d: Why do Sun and Moon appear to us at the same size?

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