"Ernie Wright" wrote in message
. ..
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

Sure of november ?
I found various sources stating "from september". Who is right ?
(note that from nov venus was gibbeous about 60% illuminated and prob. 20"
or so in size)
if nobody can confirm here I will try to find the answer at IMSS, maybe they
now it...

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.
...

August 23, 1609 is well confirmed by various sources. Remain to find the
officiel text.

Thierry


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

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