The motion of the equinoxes along the ecliptic, arising from the combined motion of the equator (lunisolar precession) and the ecliptic (planetary precession); also known as general precession. It was first detected by the Greek astronomer Hipparchus in about 130 bc from the apparent increase in the observed celestial longitudes of stars. It amounts to about 50″.3 per year. Hence the equinoxes move westwards on the celestial sphere by 1° in about 72 years and take 25.800 years to complete one circuit.