A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Amateur Astronomy
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

galileo galilei - dates to confirm



 
 
Thread Tools Display Modes
  #11  
Old September 12th 06, 07:21 AM posted to sci.astro.amateur
Brian Tung[_1_]
external usenet poster
 
Posts: 755
Default galileo galilei - dates to confirm

Ernie Wright wrote:
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 incidentally also (mostly) makes sense in Latin: "These unripe
things are read in vain by me"--ostensibly an indication of the
prematurity of the observations at that time. He wanted to stake a
claim to primacy, but the scientist in him wouldn't let him make the
claim before he was certain it was right. The 'o' and 'y' are in there
just to make the anagram come out right.

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.


--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
  #12  
Old September 12th 06, 11:42 AM posted to sci.astro.amateur
external usenet poster
 
Posts: n/a
Default galileo galilei - dates to confirm


"Brian Tung" wrote in message
...
robert casey wrote:
Also heard that the scope Galileo had was a real POS, and he would have
loved to have gotten his hands on one of our Christmas gift trash scopes
from WalMart. Even though those are POS's, they'd better his POS...


As I understand it, it wasn't the execution so much as the design. It
had inherent aberrations, but the scopes he produced performed about as
well as a modern example of the same design would. There was a recent
article in Sky and Telescope or Night Sky about this.


I confirm Brian.
The patent was already almost in the public domain as the design was really
simple.
Galileo simply improved the design but lenses being very expensive (and they
are always), most lenses show bubble, colors and other artifacts (see the
collection at IMSS, firenze)
However, thanks to his scopes enlarging from 3 to 30x + only he disovered
all we know.
His best scopes, even if they show a small FOV (15-45') and poor ep. are of
excellent quality for the time.

Thierry
http://www.astrosurf.org/lombry/galilee-lunettes.htm


--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html



  #13  
Old September 12th 06, 12:33 PM posted to sci.astro.amateur
external usenet poster
 
Posts: n/a
Default galileo galilei - dates to confirm


"William Hamblen" wrote in message
news
On 2006-09-11, Thierry Thierry wrote:

A question about historical truth.
It is said that Galileo discovered the phases of Venus phases in 1610.
OK.
It is also said that he invented his scope only in 1610
Two dates to be confirmed, and if possible in the month close...

If I simulate the sky at that time, of Firenze, arcetri, we discover that
in

...
However it would have published his Siderius Nuncius in March 1610 (also
to
re-confirm).

....
The phases of Venus are in "Dialog Concerning the Two Chief
World Systems", which printed in 1632, and aren't in "Starry
Messenger", which was printed in 1610. There are fairly recent
English translations of both (Stillman & Van Helden).

I've got the Reston bio of Galileo around here somewhere. As
best as I remember, Galileo made a telescope sometime in 1609,
not long after news of the invention reached him.


Indeed. One more of my mistakes. The scope was indeed presented on August
21, 1609 (35 mm dia., 3x then 6x).
I had the Siderius but I mismatched what I read (there is long time ago).
Someone else confirmed me that there is no reference to venus in this
booklet, and the latinese text doesn't show any drawingf of venus
http://www.liberliber.it/biblioteca/...l/sidereus.htm
So Galileo had all the time to observe venus after March 1610 until his
presentation in March 1611.
Indeed, according to simulation, the crescent began to appear around the end
of 1610 and specially in dec 1610 (25") and february 1611 with a giant 57".
In sep 1610, when it seems have began to look at Venus, I think that it was
almost impossible for him to see the disk differently than a bright oval
spot, to confirm (he used a scope 3-8x only then about 30x) but venus showed
a diameter close to 12-15" only, 1/4 the one of jupiter that was already
quite small in his first scope.
So it is time for me to update my text and drawings at
http://www.astrosurf.org/lombry/galilee-hommage.htm

Thierry


Bud



  #14  
Old September 12th 06, 12:41 PM posted to sci.astro.amateur
external usenet poster
 
Posts: n/a
Default galileo galilei - dates to confirm


"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



  #15  
Old September 12th 06, 05:28 PM posted to sci.astro.amateur
Ernie Wright
external usenet poster
 
Posts: 50
Default galileo galilei - dates to confirm

Thierry wrote:

Nov 1610 - began observing Venus


Sure of november ?


No. October or even September might be a better answer, but it depends
on the exact question. It's not likely that Galileo saw any change in
phase before November, nor is it clear that he was specifically looking
for phase change prior to that.

He probably observed Venus as a morning star in the spring of 1610, so
we could also say that he "began observing Venus" almost a year before
he announced the observation of phases.

He wrote to Castelli at the end of December 1610 or the beginning of
January 1611,

Know, therefore, that about 3 months ago I began to observe Venus
with the instrument, and I saw her in a round shape and very small.

which would put the start of his observation at the end of September or
the beginning of October.

Day by day she increased in size and maintained that round shape
until finally, attaining a very great distance from the Sun, the
roundness of her eastern part began to diminish, and in a few days
she was reduced to a semicircle.

Venus was very near the horizon then, and remained low for another month
or so. It's also likely that in his instrument, he wouldn't have been
able to distinguish its phase from a disk until early to mid-November,
which is why he described its change to a semicircle as taking only a
few days.

A quick check in SkyMap produces the following for Venus.

date alt phase diam mag
---------------------------------
1 Sep 6 .86 12 -3.9
1 Oct 7 .78 14 -4.0
1 Nov 11 .68 17 -4.1
1 Dec 18 .58 21 -4.3
1 Jan 28 .41 30 -4.5

Check these numbers if you need them to be accurate. The altitude is in
degrees at half an hour after sunset at a latitude of 45N. The diameter
is in arcseconds.

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

  #16  
Old September 12th 06, 07:39 PM posted to sci.astro.amateur
canopus56[_1_]
external usenet poster
 
Posts: 556
Default galileo galilei - dates to confirm

Thierry wrote:
snip
Galileo simply improved the design but lenses being very expensive (and they
are always), most lenses show bubble, colors and other artifacts (see the
collection at IMSS, firenze)


The other thing I like about Galileo's telescope is his micrometer that
was attached to the telescope. It was used to measure the angular
positions of Jupiter's moons and the relative angular sizes of planets.
Apparently, a physical copy of the micrometer did not survive. Here's
an interesting simulation of the micrometer.

Simulation of the micrometer attached to Galileo's telescope
Institute and Museum of the History of Science in Florence
http://brunelleschi.imss.fi.it/museum/esim.asp?c=100505
(Right-hand sidebar)

- Canopus56

P.S. for lurkers -

Other pictures of Galileo's telescope at the Institute and Museum of
the History of Science in Florence
http://brunelleschi.imss.fi.it/museum/esim.asp?c=500104

These supplement the excellent photographs at Thierry's site:
http://www.astrosurf.org/lombry/galilee-lunettes.htm

  #17  
Old September 12th 06, 08:45 PM posted to sci.astro.amateur
robert casey
external usenet poster
 
Posts: 790
Default galileo galilei - dates to confirm


His best scopes, even if they show a small FOV (15-45') and poor ep. are of
excellent quality for the time.


Galileo wasn't able to make sense of Saturn. But he may have had in the
back of his mind that all objects in the sky are spheres, and tried his
best to reconcile that with what he saw of Saturn. The image size must
have been pretty small, and any issues with the scope probably made
things even harder to figure out. He thought Saturn was 3 spheres in a
row. But those side spheres varied in size over the years. I think he
just left it as an unsolved mystery to be solved later rather than
declare something as solid fact.
  #18  
Old September 22nd 06, 06:45 AM posted to sci.astro.amateur
Hupat Tipo Netscapoetrxcvc
external usenet poster
 
Posts: 4
Default galileo galilei - dates to confirm



Brian Tung wrote:

Ernie Wright wrote:
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 incidentally also (mostly) makes sense in Latin: "These unripe


unripe = "incomplete" in this context. Literalist too much you are.


things are read in vain by me"--ostensibly an indication of the
prematurity of the observations at that time.


precisely.

He wanted to stake a
claim to primacy, but the scientist in him wouldn't let him make the
claim before he was certain it was right.


precisely, his character at work.

The 'o' and 'y' are in there
just to make the anagram come out right.


you sure about that? oyvey!



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.


--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html


  #19  
Old September 22nd 06, 05:00 PM posted to sci.astro.amateur
Brian Tung[_1_]
external usenet poster
 
Posts: 755
Default galileo galilei - dates to confirm

Yoda wrote:
Haec immatura a me iam frustra leguntur o y


Which incidentally also (mostly) makes sense in Latin: "These unripe


unripe = "incomplete" in this context. Literalist too much you are.


"Unripe" in English "incomplete" also means.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
28 December 2005 : New step for the Galileo System POLE STAR Policy 2 December 30th 05 12:24 PM
First Galileo satellite on orbit to demonstrate key technologies(Forwarded) Andrew Yee News 0 December 30th 05 02:15 AM
Galileo End of Mission Status Ron Baalke History 65 October 30th 03 03:31 PM
Galileo End of Mission Status Ron Baalke Astronomy Misc 15 October 10th 03 04:19 AM
The Final Day on Galileo Ron Baalke Science 0 September 19th 03 07:32 PM


All times are GMT +1. The time now is 11:22 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.