| He considered the Euler angles and studied rotational problems which were motivated by the problem of the precession of the equinoxes. |
| Einstein's theory predicts that such gyroscopes will undergo geodetic precession merely because space-time is curved in the planet's vicinity. |
| Because of the precession of the equinoxes, the equinox and solstice points have each moved westward about 30 degrees in the last 2,000 years. |
| Of course, the anomalous precession of Mercury was already known, and general relativity could explain it. |
| 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. |
