1,309. The Orbits of the Moon

Hilchos Kiddush HaChodesh 13:11

Now that we can calculate the position of the sun on any date we like, we will also be able to calculate the actual date of any equinox or solstice we want, both for those in the future – meaning subsequent to whatever date we set as our starting point – and for those in the past.

Hilchos Kiddush HaChodesh 14:1

There are two average rates of progress that are relevant to the moon, which travels in a small orbit not completely around the Earth. The average progress of this orbit is called the average of its path. This smaller orbit in turn follows a larger orbit that encircles the Earth. The average progress of the smaller orbit within the larger one is called the moon’s average. The daily rate of progress for the moon’s average is 13 degrees, 10 minutes, 35 seconds (13, 10, 35).