“Because of the precession of the equinoxes the tropical year is shorter by about 21 minutes than the sidereal year.”
“This is the phenomenon of precession, caused by the Earth's axis slowly rotating around the celestial poles.”
“Of course, the anomalous precession of Mercury was already known, and general relativity could explain it.”
predecessor
One who precedes; one who has preceded another in any state, position, office, etc.; one whom another follows or comes after, in any office or position.
A model or type of machinery or device which precedes the current one. Usually used to describe an earlier, outdated model.