Conventional International Origin
Encyclopedia
Conventional International Origin is a conventionally defined reference axis of the pole's average location over the year 1900.

Polar motion
Polar motion
Polar motion of the earth is the movement of Earth's rotational axis across its surface. This is measured with respect to a reference frame in which the solid Earth is fixed...

 is the movement of Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's rotation axis
Rotation
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...

 across its surface. The axis of the Earth's rotation tends, as the axis of a gyroscope, to maintain its orientation to inertial space
Inertial space
In physics, the expression inertial space refers to the background reference that is provided by the phenomenon of inertia.Inertia is opposition to change of velocity, that is: change of velocity with respect to the background, the background that all physical objects are embedded in....

. The Conventional International Origin is used to measure this movement.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK