Whelp, my mind is blown. Embedded here for your convenience is today's posting by Suspicious 0bservers. The Sun-Earth-Moon 'three-body problem" exhibits periodicity at 9, 72, 230, and 1200 year intervals:
With charts and graphs.
Can you guess where we are on the curve right now?
Plus which, because of the Moon's apogee and perigee, it's gravity can vary more than 40% on a vector that wanders through the North and South hemispheres on IIRC a different cycle. The molten core of the earth has 'tides' of up to 1.4km [citation needed] and as the tectonic plates relax after the peak is when you get earthquakes.
19:21 out of your day at speed=1.