Good-morning, BlueKnight.
I'm not really clear on the question: I'll try to answer several points.'
First, we strongly recommend that if you're going to use Moon's node, you use the True Node. The mean (average) position of the True Node without all the calculations being applied. Using it is like using the mean (average) Sun by advancing Sun a little more than 0°59'/day regardless of its real speed. As you noted, the mean node can be quite a bit in error.
That being said, whichever you use - it is a point on the zodiac (two opposite points. Moon's nodes are the two opposing points on the zodiac where the Moon's orbit crosses the ecliptic (zodiac). This doesn't have a starting point any more than anything else in a horoscope has a starting point; e.g., where would you say "Mercury's starting point" is? It's the same sort of question. Like Mercury or Sun or Moon or whatever, Moon's nodes rotate the zodiac; except, like the vernal point, they move retrograde (the Mean Node is
always retrograde, the true node loops between retrograde and occasionally direct).
BlueKnight22 wrote: Mon Nov 22, 2021 8:38 am
So, since they are close by in position, what is the reasoning for the determined position of the Mean north node? It seems arbitrary, but I would like to know the reasoning/geometry behind it.
This would be easy if you understood spherical geometry as used in positional astronomy. I more or less gave the answer above, though: When one calculate the nodal positions, the
mean position is one step along the way to calculating the
true position.
Mean means "average." These aren't two different things: It would help if you add the words "position of" in their names: The
mean (average) position of Moon's north node is one stop along the way to calculating the
true position of Moon's north node.
