Earth's rotation rate

The earth's rotation rate changes every day by thousands of nanoseconds, and this is due in a large part to wind.

Even the Earth's rotation rate has more drift and variation in drift than an atomic clock.

The Earth's rotation rate is still slowing down, though gradually, by about two thousandths of a second per rotation every 100 years.

But we could launch payloads for hundreds of thousands of years before detecting even the slightest slow-down in the Earth's rotation rate.

Precise astronomical angular measurements require knowledge of the Earth's rotation rate and nutation, both of which are influenced by Earth tides.

Of the fundamental toroidal modes, T represents changes in Earth's rotation rate; although this occurs, it is much too slow to be useful in seismology.

It has been speculated that changes in the Earth's rotation rate may have helped to trigger geomagnetic reversals during the Pleistocene (e.g. [7]).

Cuk and Stewart's study, which appeared online Wednesday in the journal Science, also provides a mechanism by which Earth's rotation rate could have slowed over time.

Global sea level is also affected by vertical crustal movements, changes in Earth's rotation rate, large-scale changes in continental margins and changes in the spreading rate of the ocean floor.

The Shortt was the first clock to be a more accurate timekeeper than the Earth itself; it was used in 1926 to detect tiny seasonal changes in the Earth's rotation rate.

By the 1950s it had become clear that the Earth's rotation rate was not constant, so astronomers developed ephemeris time, a time scale based on the positions of solar system bodies in their orbits.

The present rate of change is that the Earth's rotation rate is slowing by 16 seconds every million years and the distance of the Moon is increasing by 120 cm each year.

The first large ring had a lock-in frequency of about 2 kHz, and the first ring that could measure the Earth's rotation rate had a lock-in frequency of about 20 Hz.

All kinds of factors constantly distort the standards by which ordinary people measure time, and something far more accurate than the Earth's rotation rate is needed to time such split-second events as course corrections for interplanetary space probes.

The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles.

The characteristic coupling time between core and mantle has been estimated to be on the order of ten years, and the so-called 'decade fluctuations' of Earth's rotation rate are thought to result from fluctuations within the core, transferred to the mantle.

A part of the answer was suggested independently in the 1860s by Delaunay and by William Ferrel: tidal retardation of Earth's rotation rate was lengthening the unit of time and causing a lunar acceleration that was only apparent.

For example, Coerte V. Voorhies of the Goddard Space Flight Center in Greenbelt, Md., suggested that variations in core currents pressing on mantle protruberances alter the earth's rotation rate and the length of the day by fractions of a second.

Measured on a strictly uniform time scale, such as that provided by an atomic clock, the mean synodic month is becoming gradually longer, but since the tides slow Earth's rotation rate even more, the mean synodic month is becoming gradually shorter in terms of mean solar time.

A fast-spinning Earth One of the studies — by Matija Cuk of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, Calif., and Sarah Stewart of Harvard — suggests the answer lies in Earth's rotation rate.