# How does the moon orbit vary with time?

Sep 23, 2016

It is an ellipse relative to the Earth. Relative to the Sun, it is a spiral over a torus, around the orbit of the Earth..

#### Explanation:

Relative to the Earth, the orbit is an ellipse in a plane inclined at

about ${5.15}^{o}$ to the Earth's orbital plane, ecliptic. Moon crosses

ecliptic every fortnight, nearly. These ascending and descending

nodes nodes are not fixed with respect to the line of centers of the

Earth and the Sun, the Sun-Earth Arm (SEA). The distances from the

Earth, nearest perigee and the farthest apogee, in every revolution.

over a lunar month are also not fixed. These variations over long