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Re: Does the earth wobble?

David Brez Carlisle wrote:
>The wobble is not measured, to reply to James Shields query.
>It's inferred.  The woble is not a sub-harmonic of any 
>longer term cycle.

Excuse me for being so painfully slow, but what is it inferred from?

There may not be any harmonics involved, but it still seems possible (and
very hard to disprove, given the time-scale) that there is a seperate
"wobble" or "drift" of the angle, occuring very slowly over a much longer
period of time.

Alex W. Hertzog wrote:
>paleontology. So I'll give my idea: I don't think the Earth is tilted any 
>more or less than is has been, or at least not to a noticeable effect.

My original idea was that when the Earth first formed, 4.5 Ga, it would
probably have been "on the level", and that since then it has tilted by
about 24 degrees. Now, it seems that at some point the moon came along
(probably at least 4 Ga, so this isn't going to be a factor in dinosaurs),
and it has kept the Earth spinning on a stable axis. Does the moon orbit on
an axis tilted at the same angle? Is it possible that the angle of the
moon's orbit changes? Similarly, if the angle of our solar system was
changing within the Milkey Way, it would be almost impossible given the HUGE
periods involved.

>There are so many factors that affect global climate, it's a real shot in 
>the dark to pin it down to one. 

Agreed. There were many factors affecting the climate. The most obvious one
I can think of is the amount of CO2 in the air. However, it is very hard to
get away from the fact that the poles were in darkness for half of the year.
This would make life pretty harsh for any dinosaurs living there. Of course,
another possibility is that they hybernated for the winter. Large bodies
would probably be an advantage for long periods of hybernation.

>If the Eart wobbles, it is most likely 
>that it's the result of a huge meteor impact.

Now this I really doubt. If I remember my physics, you would need a huge
meteor travelling incredibly fast to have even a slight effect on the
trajectory of the Earth. On the other hand, it mightn't take so much to add
a little to the spin, like putting spin on a cue-ball. Anyone like to try
out some figures to see if its plausible?

>The earth wouldn't move fast enough or far enough to kill off the 
>dinos, or we'd at least have a killer world record crater. So, in a 
>nutshell, I have a lot of doubt that axial tilt had anything to do with 
>the dinos.

I certainly don't think tilt or wobble or spin has anything to do with the
extinction of the dinosaurs. I raised the subject entirely in relation to
dinosaurs living near the poles.

Sorry (again) if I'm dragging this on longer then I should.

James Shields  -  jshields@iol.ie  -  http://www.iol.ie/~jshields
And when the ark was finished Noah said unto Elvis, "What do you reckin?"
And Elvis checked out his own cabin and shook his head saying "poky".
And so did they knock several walls through and install a jaccuzzi.
And when it was all done Noah scratched his beard and said, "We don't have
room for all the animals now."
And Elvis perused the livestock list and in his wisdom said, "Lose the
        -Robert Rankin, The Suburban Book of the Dead