An isolated nuclear spin's state can be associated with a spatial direction using the Bloch sphere representation. If the direction rotates around the -axis at a constant rate, we say that it precesses around the -axis. The motion corresponds to that of a classical top experiencing a torque perpendicular to both the -axis and the spin axis. For a nuclear spin, the torque can be caused by a magnetic field along the -axis.
The "wobble" of the Earth's rotational axis, which sweeps out an imaginary cone, much like a spinning top, once every 26,000 years. Precession changes the pole star as seen from Earth. Thuban, the brightest star in the constellation Draco, was the pole star while the Egyptians built the Pyramids in Egypt. Since that time, the motion of precession has rotated the Earth's axis away from Thuban and towards Polaris, the current pole star. In 13,000 years, Earth's rotational axis will point towards Vega, the new pole star.
The gradual conical path traced out by Earth's spinning axis; simply put, it is the "wobble" of the axis.
In an applied magnetic field, a particle with a magnetic moment will tend to rotate about the field in a motion called precession. Precession is the result of the twist due to the magnetic field acting on the magnetic moment and the particle's intrinsic rotational motion (its spin). Nuclear precession in a magnetic field is similar to the precession of a toy gyroscope whose axis precesses under the twist due to gravity.
The slowly changing position of stars in the sky with respect to earth-based coordinates, resulting from the slowly varying orientation (the precession) of the earth's axis. The apparent precession of the stars is the result of the actual precession of the earth's axis.
A change in some direction, due to changes in the orbital or rotational motion of an object. There is often more than one such change going on at the same time. E.g., the perihelion of Mercury's orbit precesses because of the gravitational influences of other planets, and more famously because of the difference between relativistic (Einsteinian) and classical (Newtonian) mechanics. Similarly, as noted below, the Vernal Equinox precesses both because of changes in the rotation of the Earth, and in its orbital motion.
A comparatively slow gyration of the rotational axis of a spinning body about another (intersecting) axis so as to describe a cone. Caused by the application of a torque tending to change the direction of a rotational axis. See nuclear magnetism log.
the uniformly progressing motion of the pole of rotation of a freely rotating body undergoing torque from external gravitational forces. In the case of the Earth, the component of precession caused by the Sun and Moon acting on the Earth's equatorial bulge is called lunisolar precession; the component caused by the action of the planets is called planetary precession. The sum of lunisolar and planetary precession is called general precession. (See nutation.)
(MRI) The spin of protons around the axis of the magnet.
slow wobble of an object's rotation axis or an object's orbit. The precession of the Earth's rotation axis is caused by the gravitational pulls of the Sun and the Moon on the Earth's equatorial bulge.
This catch all term is now used to describe both the phenomenon of the precessing equatorial point as well as the Earth movement itself.
Systems in Motion with Respect to Each Other Involving 90 Degrees
comparatively slow gyration of the axis of a spinning body so as to trace out a cone. Caused by the application of a torque tending to change the direction of the rotation axis and continuously directed at right angles to the plane of the torque. The magnetic moment of a nucleus with spin will experience such a torque when inclined at an angle to the magnetic field, resulting in precession at the Larmor frequency.
the motion of a spinning body (as a top) in which it wobbles so that the axis of rotation sweeps out a cone
a complex motion excuted by a rotating body subjected to a torque tending to change its axis of rotation
A rotation of the direction of the axis of rotation. Normally refers to the precession of the equinoxes, a consequence of the effect of the Sun's gravity on Earth's equatorial bulge. Earth's axis of rotation precesses with a period of about 25,770 years, during which time the equinoxes make a complete revolution about the celestial equator. Because the Vernal Equinox is the reference direction for the equatorial co-ordinate system, the co-ordinates of "fixed" objects changes with time and must therefore be referred to an epoch at which they are correct.
Change of direction of the axis of a rotating body due to applied torque.
A 26,000 year wobbling cycle of the Earth's rotation axis that causes a gradual shift of the celestial poles and celestial coordinates
alternative to obliquity for description of element orientation in plan view. The common scientific use of precession is related to orbital motions which are not analogous to the element orientation. Hence the special use of this term for coccoliths is obscure.{Black 1972
A modern term, derived from the precession of the equinoxes and meaning a motion around a cone of the rotation axis of a spinning body.
Uniform motion of the axis of a freely rotating body (such as a top) because of external forces. Earth has a precession angle of approximately twenty-three and a half degrees and completes the precession circle in a period of 25,800 years.
The slow change in the direction of the axis of a spinning object, caused by some external influence.
A change in the direction of the axis of spin of a rotating body.
Circular motion about the axis of rotation of a body; fixed with respect to the stars. The Earth is a giant gyroscope whose axis passes through the North and South Poles and this axis precesses with a period of 27,700 years.
A slow circular motion about the lower vertical axis of an accretion disk.
wobble in Earth's axis that, over a cyclical period of 23,000 years, influences the time at which the earth is closest to and farthest from the sun; ultimately, this affects the timing of the changes of the seasons on Earth.
the slow, periodic change in the direction an object’s rotational axis caused by the gravitational influence of another body
A slow, conical motion of the Earth's axis of rotation, caused principally by the gravitational pull of the Moon and Sun on the Earth's equatorial bulge.
(of the equinoxes) - A measure of the slow clockwise motion of the equinoxes along the ecliptic due to the motion of the earth's axis of rotation around the pole of the ecliptic; the angular movement of the spin axis of an object around an axis fixed in space.
The angular motion (tilting) of the axis of a spinning or rotating body caused by a torque whose axis is not parallel with the axis of rotation.
The slow, smooth increase or decrease of an angle. When used to describe the changing orientation or an orbit, one can imagine an ellipse (the orbit) spinning around a central point. When used to describe a spinning body, it is the circular gyration of the body's rotation axis.
A westward movement of the equinox caused by the movement of the celestial pole.
The slow migration of Earth's axis that traces out a cone over a period of ~26,000 years.
Due to the pole of the equator revolving around the pole of the ecliptic, the equinoctial point moves backward with relation to the constellations at the rate of approximately 50" per year. It makes a complete revolution through the twelve constellations in the great cosmic year of 25,920 earthly years, or 2160 years to pass through one constellation. There is disagreement among authorities as to the exact position of the vernal equinox (0° Aries) at present, but all are agreed that it is approaching the end of the Age of Pisces and entering the Age of Aquarius.
The circular motion of Earth's axis around the pole of the ecliptic, caused by the gravitational pull of the Sun and Moon on the bulging part of the equator. One complete revolution takes approximately twenty-five thousand years to complete.
The slow change in the direction of Earth's axis of rotation. One cycle takes nearly 26,000 years.
Precession refers to a change in the direction of the axis of a rotating object. In physics, there are two types of precession, torque-free and torque-induced, the latter being discussed here in more detail. In certain contexts, "precession" may refer to the precession that the Earth experiences, the effects of this type of precession on astronomical observation, or to the precession of orbital objects.
