An epitrochoid is the path traced by a point on a circle (M)
that travels on the outside of another circle (E).
This can be used to model the path of the Moon (M) in orbit around the Earth (E).
There are about 13.3 revolutions(n) of the Moon about the Earth in one year.
-credit-Malin Christersson-[url]http://www.geogebratube.org/material/show/id/87141[/url]
