Re: Bulges

["Donald E. Simanek" <dsimanek@eagle.lhup.edu>]

On Mon, 3 Mar 1997, Igal Galili wrote:

> > I agree that your potential approach is a superior way to do this. I'm
> > curious, though, what you get as an answer when you consider the case
> > where the two bodies are *not* rotating. I predict you will get the result
> > that there are two opposing tidal bulges even in that case, simply from
> > the gravitational force gradient. Therefore textbooks shouldn't imply that
> > rotation is the *sole* cause of the bulges. However, it would be
> > interesting to compare the size of the non-rotational bulges, with the
> > size of them when the system is rotating, to see which cause is the
> > predominant one for the bulges.
> >
> >        -- Donald
>
>         Please, excuse my intrusion.  There is an interesting point here.
> "Non-rotational bulges" are  not symmetrical, reflecting the profile of the
> gravitational force gradient. The additions due to the centrifugal forces
> make the bulges symmetrical.  This point usually is not mentioned by many
> books, probably for the sake of simplicity, which could be understood.
>
> Igal.

Now *there's* an interesting new piece of info for this thread. I
suspected the two effects might combine to tend toward symmetry, but
haven't yet had time to sit down to do the messy math. The field gradient
effect would cause a bulge greater on the lunar side of the earth. The
centrifugal effect would distort the equatorial bulge more on the opposite
side. Does this make the resulting two-bulge shape close to symmetrical,
or exactly symmetrical. If *exactly*, that's astounding, and *very*
interesting.

	-- Donald

......................................................................
Dr. Donald E. Simanek                            Office: 717-893-2079
Prof. of Physics                    Internet: dsimanek@eagle.lhup.edu
Lock Haven University, Lock Haven, PA. 17745          CIS: 73147,2166 
Home page: http://www.lhup.edu/~dsimanek            FAX: 717-893-2047
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