From: Piotr Gasiorowski
Message: 3505
Date: 2000-08-31
----- Original Message -----From: petegraySent: Monday, August 28, 2000 7:51 PMSubject: Re: [tied] Ancient Egyptian calendar problems
Peter wrote:The classical Greeks likewise had not solved the problem of how long the
year is, though later Greek science was able to establish a whole bunch of
stuff (such as precession of the equinoxes) better than astronomers in the
1800's.
Are you sure? Do you mean they were able to determine it more accurately? Astronomers around 1800 had very precise tools for observing the sky and powerful analytic methods at their disposal (cf. Gauss's precise calculation of the orbit of Ceres). I somehow can't believe they did worse than the Greeks. D'Alembert proposed a correct analytical solution of the precession of the exinoxes as early as 1749. Earlier, Ptolemy ascribed it to the "wobbling" of the outermost orbis coelestium, while Copernicus argued that it was the axis of the Earth that wobbled, but as for the parameters of the rotation, I don't think that the empirical estimate of the precession period (Platonic year) could change much from the time Hipparchus discovered it till the beginnings of modern astronomy.
Piotr