I understood the argument that the speed of the Earth's orbit dominated the Moon's, but I was having a really tough time visualizing it. The wiki article (http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Path_of_Earth...) has a diagram that explains it (http://en.wikipedia.org/wiki/File:Moon_trajectory1.svg)
The (wrong) graph has been drawn with 12 cycles, based on approximately 12 lunar months per year. But the result is obviously not to scale. If you try to draw it to scale, the truth jumps out at you; it can't have this form.
I understood the argument that the speed of the Earth's orbit dominated the Moon's, but I was having a really tough time visualizing it. The wiki article (http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Path_of_Earth...) has a diagram that explains it (http://en.wikipedia.org/wiki/File:Moon_trajectory1.svg)