Re: Sig Figures and tides

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

David Bowman (and others).....
I'm sure that there are many other participants on this network
besides myself who were unaware of the problems that
arise when observing the motions of celestial objects that
are more than 28 AU from the earth's spin axis.  Thanks
especially for bring this to my attention.  It would be
greatly appreciated if you would cite an available refernce
where this topic is discussed at greater depth.

Thanks again....     Herb Gottlieb

On Thu, 03 Feb 2000 07:18:31 -0500 David Bowman
<David_Bowman@GEORGETOWNCOLLEGE.EDU> writes:
> Regarding Herb's comment:
> ...
> > In space everything is in relative motion. Although it is much
> simpler to describe the sun and the moon as celestial objects that are
> relatively still with respect to the earths motions,  there is nothing
wrong by
> believing that the earth is motionless and everything else in space is
in
> motion.
> > Gottlieb from New York City
> > (Where the sun rises in the East and sets in the West )
>
> There might not be anything practically wrong with such a
> perspective for a practical prescientific description, and
> there is nothing morally wrong with this description either.
> But there *is* something   scientifically
> wrong with it if it is to be used to describe the motions of objects
> farther than about 27.48 AU from the earth's spin axis.  The
> rotating coordinate system in which the earth's surface is at rest has
a
> cylinderical coordinate singularity at this distance from the
> rotation  axis, and it cannot be used for distances greater than that.

> (Objects greater that this distance travel at speeds greater than c in
this
> coordinate system.)  Such a situation *is* a real problem for a
> proper scientific (i.e. relativisitic) description of the motions of
> distant heavenly bodies.  Even Neptune and Pluto are in this forbidden
> region--  let alone all the Kuiper belt objects, all the stars (other
than the
> sun)  and interstellar gas and dust clouds, all the galaxies, all the
> galactic clusters, all the superclusters, all the quasars, all the
> inhomogeneities in the cosmic microwave background, etc.
>
> David Bowman
> David_Bowman@georgetowncollege.edu