North node, South node correct understanding

Question

What is the correct concept of the North node and South node? There is some conflicting information on the internet.

Which one of these two is correct?

1. Sourced from some Astrology material - How can North and South be 180-degree opposites in this since these are on one side of the orbit curve?

https://astrologyquestionsandanswers.com/2016/10/12/major-and-minor-chords-the-moons-nodes-part-two/

https://www.spiritdaughter.com/blogs/align-with-magic/a-shift-in-perspective-the-north-node-moves-to-gemini

http://astrologyclub.org/eclipses-and-the-moons-nodes/

2.From Wikipedia source - This seems incorrect too since there is no "separate" Moon orbit as per around the Sun

https://en.wikipedia.org/wiki/Lunar_node

http://www.antidotebrooklyn.com/celeste-blog/2019/4/21/riding-the-tail-of-the-celestial-dragon

Answer 1

The first few diagrams show the lunar nodes coinciding with the first and last quarter phases, which is only the case every 173 days or so. When the nodes are aligned with the new and full phases, eclipses can occur:

In this diagram from timeanddate.com, our point of view is north of the ecliptic, the ascending node ☊ is in the 5 o'clock direction, and the descending node ☋ is in the 11 o'clock direction. Nodal precession moves them retrograde (clockwise from north) about 19.4° per year, an 18.6 year cycle mostly due to the Sun's gravity.

Answer 2

𝟏. In astronomy (as opposed to astrology, a pseudoscience which was often proven wrong), we don’t talk about “north” and “south” nodes, but about “ascending” and “descending” nodes.

𝟐. The first two images and the fourth one show the Earth’s orbit as too tight a curve; this is what makes you have a hard time understanding. Since they come from astrology-related sources, I’m not surprised they can’t be trusted.

𝟑. The ascending node is the place where the Moon crosses the apparent yearly path of the Sun (the “ecliptic”) from the south to the north; the descending node is where the Moon crosses the ecliptic from the north to the south. This is the only proper definition.

𝟒. As JohnHoltz correctly stated, the intersection of two planes is a line, so ascending and descending nodes are indeed at 180° from each other indeed, as the third, fifth, and sixth images show. (Actually, the difference is not exactly 180°, because gravitational perturbations make the orbit, an ellipse rather than a circle, slowly turn with respect to the fixed stars. Hence, the line of nodes makes a full 360° turn in about 18.61 years. By the time the Moon reaches the next node, it has thus advanced a little [by about 1.5°, from a quick calculation]).