The “precession of the equinoxes” is the 26,000-year circular movement of Earth’s axis. It is caused by the bulging at the equator, which makes Earth’s axis twist in such a way that the North and South Poles complete a circle every 26,000 years. Every year when the sun crosses the equator at the time of the equinox, it is in a slightly different position than the previous year. This movement proceeds eastward until a circle is completed.