"Weatherlawyer" wrote in message
oups.com...

First in browsing the astronomy groups I came upon sci.astronomy only
to find it is no longer in use. Or is it just Google no longer posting
to it? How come it went out of fashion, anyone know?

And now to business:
I was trying to find out more about the Chandler Wobble on here "only
to find" no one has mentioned it in several years.

May I take you are all as much in the dark about it as I am?

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Very interesting topic, Weatherlawyer.

For those unfamiliar: the Chandler Wobble is a phenomenon discovered by
American astronomer Seth Chandler before the turn of the century. It
describes a small irregularity in the Earth's rotation whereby the Earth's
axis 'wobbles' slightly, a bit like that of a spinning top slowing down.
Rather than spinning at a point, the north pole effectively moves in little
spirals of increasing or decreasing size, of a few metres diameter. The
magnitude of the wobble varies, almost stopping at times and becoming more
extreme at others. The Jet Propulsion Lab's Dr Gross issued a statement
some 15 years ago that he believed it was all due to varying pressures at
the bottom of the oceans, caused by changing temperatures, winds and
salinity and resultant currents, etc. ... all very complicated.

More interesting still is the (unproven) theory that volcanic and seismic
activity is linked to the 6.5 year average cycle of the wobble's maxima and
minima. There is certainly some statistical evidence to suggest that there
is a degree of harmonic regularity to volcanic outbursts and earth/sea
quakes and one may even derive a cyclic period from bunches of peaks on the
graphs, but there is no clear synchronicity with our friendly wobble, even
allowing for lags due to the huge mass of the earth.

References:
http://www.abc.net.au/science/news/e...ish_153343.htm
http://www.michaelmandeville.com/pol...relations2.htm