Lunar precession

The moon's eliptical orbit precesses about once in just under 9 years. It is caused by the solar tide.

This precession period is equal to the time that number of sidereal months counted exceeds the number of anomalistic months counted by exactly one.

This precession causes the full moon cycle (fumocy) to be over a month longer than a sidereal year.

There are approximately two precession cycles in a Saros cycle.