{{Use dmy dates|date=July 2024}} {{Short description|Reference axis of the pole's average location on the Earth's surface over the year 1900}} '''Conventional International Origin''' ('''CIO''') is a conventionally defined reference axis of the pole's average location on the Earth's surface over the year 1900–1905.<ref>{{cite web | url=http://mycoordinates.org/the-real-definition-of-itrf/ | title=Coordinates : A resource on positioning, navigation and beyond - Blog Archive - The Real Definition of ITRF | author=Muneendra Kumar | year=2007 | accessdate=2014-05-22 | publisher=mycoordinates.org}}</ref>
Polar motion is the movement of Earth's rotation axis across its surface. The axis of the Earth's rotation tends, as the axis of a gyroscope, to maintain its orientation to inertial space. The Conventional International Origin is used to measure this movement.
==References== {{Reflist}}
'''General''' * {{cite web | url=http://syrte.obspm.fr/iau/iauWGnfaTemp/Newsletter2.html | title=Newsletter 2 | work="Nomenclature for Fundamental Astronomy" (NFA) | author=Bernard Guinot | year=2003 | accessdate=2010-02-07 | publisher=IAU}}
Category:Precession
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