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The precession of the equinoxes is caused by the gravitational forces of the Sun and the Moon, and to a lesser extent other bodies, on the Earth. It was first explained by Isaac Newton. [31] Axial precession is similar to the precession of a spinning top. In both cases, the applied force is due to gravity.
The torque-free precession rate of an object with an axis of symmetry, such as a disk, spinning about an axis not aligned with that axis of symmetry can be calculated as follows: [1] = where ω p is the precession rate, ω s is the spin rate about the axis of symmetry, I s is the moment of inertia about the axis of symmetry, I p is moment ...
The geographic poles are defined by the points on the surface of Earth that are intersected by the axis of rotation. The pole shift hypothesis describes a change in location of these poles with respect to the underlying surface – a phenomenon distinct from the changes in axial orientation with respect to the plane of the ecliptic that are caused by precession and nutation, and is an ...
Axial precession is the trend in the direction of the Earth's axis of rotation relative to the fixed stars, with a period of about 25,700 years. Also known as the precession of the equinoxes, this motion means that eventually Polaris will no longer be the north pole star .
The cycle which Plato describes is one of planetary and astral conjunction, which can be postulated without any awareness of axial precession. Hipparchus (c. 120 BC) is the first Greek credited with discovering axial precession roughly two hundred years after Plato's death (see below).
The first phase is created by a wobbling of the Earth's axis of rotation and is known as axial precession. While the second phase is known as apsidal precession or procession of the ellipse and is related to the slow rotation of the Earth's elliptical orbit around the Sun. When combined these two phases create a precession of the equinoxes that ...
Lunar precession is a term used for three different precession motions related to the Moon. First, it can refer to change in orientation of the lunar rotational axis with respect to a reference plane , following the normal rules of precession followed by spinning objects.
As the disk gradually decreases its azimuthal rotation, there is also a decrease in amplitude and increase in the frequency of the disk's axial precession. [5] The evolution of the disk's axial precession is easily visualized in a slow motion video by looking at the side of the disk following a single point marked on the disk.