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Re: galileo galilei - dates to confirm

Subject: Re: galileo galilei - dates to confirm
From: Ernie Wright
Date: Tue, 12 Sep 2006 00:33:37 -0400
Newsgroups: sci.astro.amateur
Thierry wrote:

Who could find me the exact dates (invention of Galileo's scope, 1st
obs., obser. of Venus phases, publication of Messenger, etc)

He observed the phases of Venus about eight months *after* he published
Sidereus Nuncius.

   Aug 1609 - completed and demonstrated a 9x instrument
   Nov 1609 - completed a 20x instrument and began observing the sky
   Mar 1610 - published Sidereus Nuncius
   Nov 1610 - began observing Venus
   Dec 1610 - announced observation of Venus phases

Galileo demonstrated the 9x telescope to the Senate of Venice on 23
August 1609.  (Galileo describes the demonstration in a 29 August 1609
letter which says, "...it has been 6 days since...")  They observed
ships at sea, not the sky.

The letter at the beginning of Sidereus Nuncius dedicating the book to
Cosimo II de Medici is dated 12 March 1610.

Galileo announced his observation of the phases of Venus in a letter to
Giuliano de Medici dated 11 December 1610.  He hid the announcement in
the form of an anagram,

   Haec immatura a me iam frustra leguntur o y

which when unscrambled is

   Cynthiae figuras aemulatur mater amorum
   The mother of love emulates the figures of Cynthia
   Venus has phases like the Moon

This is all from Albert Van Helden's English translation of Sidereus
Nuncius.

- Ernie                                  http://home.comcast.net/~erniew


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