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Re: Nutation

"These wanderings have both a seasonal component and a longer term
component and are presumably related to changes in the Earth's
inertia tensor due to such things as seasonal changes in the
Earth's mass distribution and slow climatic changes that
redistribute mass over the earth over somewhat longer time scales
(melting pack ice, changes in ocean currents), and other things
like maybe tectonic motions & such."


Goldstein derives the expected "wandering" due to the inequality of the moments of inertia* to be ~ 10 months and the amplitude is found to be about 15 feet. This is a force free wandering.

* [I(1)-I(3)]/I(1) = 0.003


I think it was Science (JAAAS) that reported the earth slowed (its rotation) an easily measured amount during the last major El Niño. A year later it had returned to normal.


"Also besides this 41 kyr +/-2 deg nutation there
is supposedly a much shorter term nutation of about 9.18 arcsec in
amplitude and has an 18.6 yr period. I don't know anything about
what causes it, though."

could it be due to the nearby planets, or the not so nearby much massier ones?

bc



David Bowman wrote:

Regarding Jim G's original questions on this thread:



Do I understand the following :



cut