Subject: Re: [HM] Indian astronomy and mathematics
From: Don Cook (tdctdc@surfsouth.com)
Date: Sun Feb 13 2000 - 01:49:19 EST
Dinesh wrote:
> From: Dinesh Maheshwari <dsm@cypress.com>
> To: historia-matematica@chasque.apc.org
> Subject: Re: [HM] Indian astronomy and mathematics
> Date: Fri, Feb 11, 2000, 7:44 PM
>
> BTW, my understanding is that the Copernicus' system had less epicycles
> than employed in Ptolemic system (80 circles), but a recent post suggests
> otherwise; can someone please clarify.
> Also, I remember reading somewhere (I apologize, I cannot remember
> where) that Galileo was able to see the different phases of Venus using
> the telescope and was thus able to confirm that the earth was moving.
> Can someone corroborate this ?
In "History and Demonstrations Concerning Sunspots and Their Phenomena" Rome
1613 (translation by Stillman Drake) Galileo writes in a letter addressed to
Mark Weber concerning remarks by Apelles (a pseudonym for Father Christopher
Scheiner)
"I am astonished that nothing has reached his ears-or if anything has,
that he has not capitalized upon it-of a very elegant, palpable, and
convenient method of determining this, discovered by me about two years ago
and communicated to so many people that by now it has become notorious. This
is the fact that Venus changes shape as does the moon;...
These things leave no doubt about the orbit of Venus. With absolute
necessity we shall conclude, in agreement with the theories of the
Pythagoreans and of Copernicus that Venus revolves about the sun just as do
all the other planets. Hence it is not necessary to wait for transits and
occultations."
Two Comments:
1. The lack of observing a transit of Venus is quite troubling for
astronomers looking for proofs of a heliocentric system: If Venus revolves
around the sun, then its path would cause a dot to move across the sun's
face. By 1613 none had been observed. One reason given for this by opponents
of Copernicus is that Venus revolves around the earth.
2. Denish refers to the Ptolemic system. There is no Ptolemic system!
Each planet has its own system incompatible with the other planets.
Copernicus has a unified system. He writes
"Nor have they been able thereby to discern or deduce the principal
thing-namely the shape of the Universe and the interchangeable symmetry
of its parts. With them it is as though an artist were to gather the
hands,feet, head and other members for his images from diverse models, each
part excellently drawn, but not related to a single body, and since they in
no way match each other, the result would be a monster rather than man.²
This unified system is a major reason that many accepted heliocentrism.
Beauty moves the earth!
Peace,
Don Cook
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