Re: A rotating Earth?

[Joseph Bellina <jbellina@SAINTMARYS.EDU>]

On the contrary, the first thing Kepler tried was Brahe's toughest
problem...Brahe's choice, Mars...his "war with Mars" lasted for several
years.  Nothing else was done at the time that he gave up on circular
orbits for Mars, so I see no justification for a claim that most things
worked. Check Kuhn before you remember Sagan.

It is interested that the volume by Copernicus had two parts.  The first
in which Copernicus showed that choosing to have the earth move lead to
great simplications in the sorts of models one had to build...indeed
each planet no longer had to have the major epicycle...interest clue
no?  But the second and longer part of the book where he tried in detail
to make the model work failed miserably, yielding a result no less
complicated that Ptolemy's.  Given that Copernicus was a neoplatonist
who believed in the simple perfection of the heavens, to him his book
must have been a failure.  I suggest to my students that Copernicus, the
person we wrongly identify as first suggesting the earth went around the
sun was for all intents and purposes a reactionary failure.

cheers

On Fri, 4 Feb
2000, Digby Willard wrote:

> In the Cosmos episode on Kepler, I think Sagan said that most things worked
> except the orbit of Mars, which was off by 8 minutes of arc.
>
> Digby Willard
>
>
>
> > I think a more careful statement would be that Kepler showed that a
> > model based on circular motion could not work, neither the Copernican
> > nor the Tychonian.  As I recall it was a matter of a few data points
> > missing by twice Tycho precision.  Something to tell students about when
> > they wonder why precision is important.
> >
> >
> > On Thu, 3 Feb 2000, Rick Strickert
> > wrote:
> >
> > > Tycho Brahe's model was geostatic, combining parts of the geocentric
> > > and the
> > > heliocentric models.    Brahe pictured  the Sun and the moon (and
> > > presumably
> > > the stars) orbiting around the earth, but the planets rotated around
> > > the
> > > sun.
> > >
> > > Kepler, using Brahe's own data on Mars, showed that the geostatic model
> > > was
> > > not correct.
> > >
> > > Rick Strickert
> > > Radian International
> > > Austin, TX