The previous post discussing the total lunar eclipse mentioned the important concept of lunar "nodes."
It contained a link to another previous post discussing these nodes in some detail, and arguing that the nine-world cosmology found in many ancient myths comes from the fact that the ancients tracked with great care the motions of nine wandering heavenly "bodies": the sun, the moon, Mars, Mercury, Jupiter, Venus, Saturn, and the two invisible lunar nodes (which are not actually heavenly bodies but which act like one when they temporarily swallow up the sun or the moon in an eclipse).
Thus, some ancient myths depict a nine-world cosmology (including the lunar nodes) and some ancient myths depict a seven-world cosmology (minus the lunar nodes). This argument was advanced by Giorgio de Santillana and Hertha von Dechend in their indispensable 1969 treatise, Hamlet's Mill.
That previous post explained at length the somewhat complicated celestial mechanics whereby the moon's plane and the nodes move about 19.3o to the west each year, causing them to take 18.65 years to complete a full circle of 360o.
However, there is an excellent website which discusses these celestial mechanics with great clarity, and which illustrates the concept with absolutely outstanding graphics and animation -- perhaps the best so far for those wishing to understand the movement of the lunar nodes. To view it, visit "Eclipses and the Moon's Nodes," by Dwight Ennis, on the website of the Astrology Club of San Jose, California.
While the beautiful total lunar eclipse of 2011 has now passed, it is still worthwhile to take the time to understand the motion of the moon as it passes above and below the ecliptic in its orbit around earth. You can often determine whether the moon is above or below the ecliptic when you observe it in conjunction with one of the planets (or with a constellation on the ecliptic -- the zodiac constellations), simply by noting whether its path through the sky is above or below the path being followed by the planet or zodiac constellation.
Thanks to Dwight Ennis for sharing his superlative illustrations and animations of eclipses and the lunar nodes with the rest of the world.
