earth rotation

earth rotation

[¦ərth rō¦tā·shən]
(astronomy)
Motion about the earth's axis that occurs 365.2422 times over a year's period.
References in periodicals archive ?
The performance assessments addressed four topics: Earth rotation, Earth shape, Earth revolution, and clouds and weather in the Earth/environmental science class (Ernst & Glennie, 2015, pg 10).
dat) statement on the website of the International Earth Rotation and Reference System Service, responsible for the synchronization of Earth time, said in reference to the Coordinated Universal Time: "A positive leap second will be introduced at the end of December 2016.
Geophysicist Chopo Ma, of the International Earth Rotation and Reference Systems Service, said: "More and more leap seconds will be called for but we can't say one will be needed every year.
Dr Helal Al Kaabi, executive director of EMI explained: "Our latest move to add a leap second to the UAE standard time follows a decision by the International Earth Rotation and Reference Systems Service in January 2015 to add a leap second to Coordinated Universal Time at the end of June this year".
Though it all sounds a little pointless, the extra second, which was announced on Monday by the International Earth Rotation and Reference Systems Service, will be enacted to help account for Earth's slowing rotation.
During the workshop held this week in Geneva, information sessions on the definition of the time scale along with the maintenance of UTC (or clock time ) in relation to the Earth Rotation Angle (UT1) were followed by discussions on the elimination of the leap second and opting for a continuous time scale.
The irregular and long-term variations of the Earth rotation are mainly caused by the displacements of matter in different parts of the planet whose excitation mechanism is the influence of the Sun and solar activity cycles.
Every time the discrepancy between TAI and UT1 becomes too big, the International Earth Rotation and Reference Systems Service (IERS) jumps into action and announces a "leap second" - usually several months in advance.
The two mesh with lovely accuracy; the problem is that the length of day is infinitesimally slowing - and so once in a while, when the International Earth Rotation and Reference System Service decrees - most recently on Dec.
They discuss time before the 20th century, solar time, ephemerides, variable earth time, earth rotation and polar motion, ephemeris time, relativity and time, dynamical and coordinate time scales, clock developments, microwave atomic clocks, optical atomic standards, the definition and role of a second, international atomic time, coordinated universal time, time in the solar system, time and frequency transfer, modern earth orientation, international activities, time applications, and the future of timekeeping.
It has been ordered by the International Earth Rotation and Reference Systems Service in Paris.

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