precession

[ pree-sesh-uhn ]

noun

1. the act or fact of preceding; precedence.
2. Mechanics. the motion of the rotation axis of a rigid body, as a spinning top, when a disturbing torque is applied while the body is rotating such that the rotation axis describes a cone, with the vertical through the vertex of the body as axis of the cone, and the motion of the rotating body is perpendicular to the direction of the torque.
3. Astronomy.
   1. the slow, conical motion of the earth's axis of rotation, caused by the gravitational attraction of the sun and moon, and, to a smaller extent, of the planets, on the equatorial bulge of the earth.
   2. precession of the equinoxes.

precession

/ prɪˈsɛʃən /

noun

1. the act of preceding
2. See precession of the equinoxes
3. the motion of a spinning body, such as a top, gyroscope, or planet, in which it wobbles so that the axis of rotation sweeps out a cone

precession

/ prē-sĕsh′ən /

1. The rotational motion of the axis of a spinning body, such as the wobbling of a spinning top, caused by torque applied to the body along its axis of rotation.
2. The motion of this kind made by the Earth's axis, caused mainly by the gravitational pull of the Sun, Moon, and other planets. The precession of Earth's axis has a period of nearly 25,800 years, during which time the reference points on the equatorial coordinate system (the celestial poles and celestial equator) will gradually shift their positions on the celestial sphere.
3. ◆ The precession of the equinoxes is the slow westward shift of the autumnal and vernal equinoxes along the ecliptic, resulting from precession of the Earth's axis.
4. See also nutation

Derived Forms

• preˈcessionally, adverb
• preˈcessional, adjective

Other Words From

• pre·cession·al adjective

Word History and Origins

Origin of precession¹

1300–50; < Late Latin praecessiōn- (stem of praecessiō ) a going before, advance, equivalent to Latin praecess ( us ) (past participle of praecēdere to precede ) + -iōn- -ion; cession

Word History and Origins

Origin of precession¹

C16: from Late Latin praecessiō a going in advance, from Latin praecēdere to precede

Example Sentences

For the past five years, Pasham has looked for tidal disruption events that are bright enough, and near enough, to quickly follow up and track for signs of Lense-Thirring precession.

From Science Daily

Radio waves are beamed in and synchronize the precessions of the spins, temporarily flipping some of them.

From Science Daily

In ancient times before Earth’s precession shifted the stars toward the south, the stars of Crux were visible from Europe.

From National Geographic

Among other things, it was Hipparchus himself who first discovered Earth’s precession, and he modelled the apparent motions of the Sun and Moon.

From Scientific American

Hard to nitpick a team playing with the poise and precession of a Super Bowl contender.

From Seattle Times