Earth Rotation: Theory and Observation
Article first published online: 3 JUN 2011
©1990. American Geophysical Union. All Rights Reserved.
Eos, Transactions American Geophysical Union
Volume 71, Issue 46, page 1791, 13 November 1990
How to Cite
1990), Earth Rotation: Theory and Observation, Eos Trans. AGU, 71(46), 1791–1791, doi:10.1029/EO071i046p01791-02.(
- Issue published online: 3 JUN 2011
- Article first published online: 3 JUN 2011
The rotation of the solid Earth, as monitored from observatories fixed on the Earth's crust, is not constant. The measurements reveal minute but complicated changes of up to several parts in 108 in the speed of the Earth's rotation, corresponding to several milliseconds in the length of the day (LOD) and even larger variations in polar motion. Earth studies have embarked on a new era with the advent of highly accurate space geodetic techniques and the availability of complementary geophysical data sets. Techniques utilized include laser-ranging to the Moon and artificial satellites, and very long baseline interferometry (VLBI). Comparisons between techniques indicate that Earth rotation is routinely determined at the 0.05–0.10 millisecond level (approximately 2–5 cm at the equator), with higher accuracy in some cases. Geophysically interesting variations are detectable at these levels. The analysis and understanding of these phenomena draw upon and contribute to meteorology, oceanography, astronomy, celestial mechanics, seismology, tectonics, and geodynamics.