Re: A rotating Earth?

[Digby Willard <dwillard@MAIL.CENTRAL.STPAUL.K12.MN.US>]

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