1,351. How Far North or South of the Equator the Moon Will Appear

Hilchos Kiddush HaChodesh 19:10

Let’s say that one wants to know by how many degrees the moon’s position diverges north or south of the equator. First calculate the degree of inclination for the moon’s actual position and see if it’s to the north or to the south. Next, calculate the moon's first latitude and see whether that is to the north or to the south. If the latitude and the degree of inclination are both in the same direction, then add them together; if one is to the south and other is to the north, subtract the smaller of them from the larger. The result is the moon’s distance from the equator in the direction of the larger figure.

Hilchos Kiddush HaChodesh 19:11

Let’s calculate the degree of the moon’s inclination from the equator for the night of 2 Iyar of the Rambam’s current year (which is his standard date for such sample calculations). We already know that the moon’s angle in the perceived sphere of constellations is in the 19th degree of Taurus. Therefore, it is inclined about 18 degrees to the north. The moon’s latitude on this date is about four degrees to the south. We subtract the smaller number (4) from the larger (18), which tells us that the moon will be 14 degrees north of the equator. All of the numbers used in this calculation are only approximated because exactness is not required in determining the moon’s visibility.