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The Chandler Wobble



 
 
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  #1  
Old April 1st 06, 08:28 AM posted to uk.sci.astronomy
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Default The Chandler Wobble


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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  #2  
Old April 1st 06, 11:00 AM posted to uk.sci.astronomy
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Posts: n/a
Default The Chandler Wobble


"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?

---
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



  #3  
Old April 1st 06, 05:48 PM posted to uk.sci.astronomy
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Posts: n/a
Default The Chandler Wobble


TeaTime wrote:
"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?

---
Very interesting topic, Weatherlawyer.

For those unfamiliar: the Chandler Wobble is a phenomenon discovered by
American astronomer

Why so modest?
USAan 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.

What is this thing with child's tops?

When was the lst time anyone saw one of them?

Is the analogy about the top of the toy or the pointy end? Does the
pointy end move or wobble? I can't remember.

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.

Almost stopping as in reaching a "point of dwell" as might be imagined
with the declination of the moon or sun? And observed in reciprocating
engines at top and bottom dead centres under a stroboscope.

Or almost stopping as in:
""Sun, be motionless over GibŽe·on, And, moon, over the low plain
of AiŽja·lon." Accordingly the sun kept motionless, and the moon
did stand still" ?

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.

And a lot less likely than the unbelievable idea that the moon has the
power to raise enough miniscule particles of water to raise a tide,
without having the same ability to raise it all the way to the moon.

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.

The list of unproven theories like that is longer than you might be
expected to believe since no one has really looked at the subject as
far as I know.

Give us endless articles about life on Mars and you can spend as much
time and money developing rockets and satellites and etc...

I wonder what the infrastructure for something like that would cost,
compared to something a lot more useful and even more mundane.

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

Hey, I followed those two Google links too.

I also looked at the http://hpiers.obspm.fr/ site

Euhau, euhau, euhau! Zose sheez ateuing Fronjemane; zey are not zo
zurrendeure monkayz etr? Non?

  #4  
Old April 1st 06, 06:18 PM posted to uk.sci.astronomy
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Default The Chandler Wobble


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


Why so modest?


You've lost me there I'm afraid. Who is being modest and in what context?

What is this thing with child's tops?
When was the lst time anyone saw one of them?


I believe a spinning top is an understandable analogy in trying to explain
the motions involved. I think the majority of people have seen one, at
least on television or whatever.

Is the analogy about the top of the toy or the pointy end? Does the
pointy end move or wobble? I can't remember.

In the case of a top, it is the top end that precesses about. In the cae of
the earth it is both poles, with the precessionary centre somewhere between
and shifting.

Almost stopping as in reaching a "point of dwell" as might be imagined
with the declination of the moon or sun? And observed in reciprocating
engines at top and bottom dead centres under a stroboscope.
Or almost stopping as in:
""Sun, be motionless over GibŽe·on, And, moon, over the low plain
of AiŽja·lon." Accordingly the sun kept motionless, and the moon
did stand still" ?


Almost stopping as in a period of more than 2 months out of the 14 month
cycle (as seen at the beginning of this year infact). Apparently irregular
and reasons unknown.

And a lot less likely than the unbelievable idea that the moon has the
power to raise enough miniscule particles of water to raise a tide,
without having the same ability to raise it all the way to the moon.


I think the math is fairly straightfoward - escape velocity would come into
play if we wanted to consider leeching at the level you describe. Binary
star systems can do it, but they have very much higher gravities than our
puny litle system.

The list of unproven theories like that is longer than you might be
expected to believe since no one has really looked at the subject as
far as I know.


I think you will find that a great many experts have pondered this anomaly
and continue to do so.

Give us endless articles about life on Mars and you can spend as much
time and money developing rockets and satellites and etc...
I wonder what the infrastructure for something like that would cost,
compared to something a lot more useful and even more mundane.


I think that may be what is considered to be the advancement of science via
the exploration of space. If we ran a poll, I'm sure we'd find thousands of
preferences of how such funds might be best used.

I also looked at the http://hpiers.obspm.fr/ site


Yes, a concise disaply of recent meanderings. The IERS provides a good
source of facts and figures on this topic.

Euhau, euhau, euhau! Zose sheez ateuing Fronjemane; zey are not zo
zurrendeure monkayz etr? Non?


I'll have a large glass of whatever you're on, my friend.
Cheers!


  #5  
Old April 1st 06, 09:43 PM posted to uk.sci.astronomy
external usenet poster
 
Posts: n/a
Default The Chandler Wobble

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


Well there a thought, what happens when the temperatures, winds and the
salinity of the sea are affected by global warming. Where's the wobble
going to go then east, west or very erratic?

"TeaTime" wrote in message
...

"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?

---
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





  #6  
Old April 3rd 06, 03:25 PM posted to uk.sci.astronomy
external usenet poster
 
Posts: n/a
Default The Chandler Wobble

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


You may not. Get thee to a library, or consult with Prof. Michael
Chinnery of Brown University, Rhode Island, who wrote a brief analysis
of the Chandler wobble and it's possible causes many years ago for the
Open University course book 'Understanding the Earth' published by
Artemis press.
A further source is 'The rotation of the Earth', W H Munk & G J F
MacDonald, 1960, Cambridge University press.
I am aware that these refs are somewhat old but they come from a period
when my interests were less focussed.
:-)

Denis
--
DT
change nospam: n o s p a m
v a l l e ys
 




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