Abstract:
Just as the regression of the nodes of the lunar orbit is connected with the
periodicity in the eclipse phenomenon, the advance of perigee is connected with the
periodicity in the fluctuations of Moon's synodic period. From the data for 495
synodic months it is found that the gross fluctuation pattern repeats itself after about
112 synodic months, which is close to the period of one complete revolution of the
Moon's perigee. Within each gross fluctuation pattern there are eight smaller cycles
of about 14 synodic months. The causes of these features are suggested in terms of
the angles between the new moon and the perigees of the Moon and the Sun. The
dependence of the amplitude of variation with respect to various angular separations
can possibly be understood by the fact that the tidal effect on the Moon varies with
its relative distance from the Sun.
