58 calendar years) in the position of the sun with respect to the stars at an equinox . It is significant for calendars and their leap year rules. --------------------------------------------------------------------------------------------- Precession http://www.geol.binghamton.edu/faculty/barker/demos/demo10.html Purpose: Demonstration of how the Earth's equatorial bulge causes precession Supplies: Gyroscope (a bicycle wheel works well), turntable (optional) Background and