galileo galilei - dates to confirm

Hello,

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
Jan-April 1610 Venus was in the East, 10° over the horizon with 80%+
illuminated, thus very small, and at the end in the rays of sun. hard to
imagine that he observed it at that time. It nevertheless could have did it.
On the other hand, at the autumn 1609 venus shows a fine crescent, and was
higher in the sky of the morning
Idem from October 1610 but, this time in the eve.

However it would have published his Siderius Nuncius in March 1610 (also to
re-confirm).
Impossible thus that he observed the beautiful crescent of venus before
publishing his book.

It was thus to have written his explanation and signed the "go for
printing", say at least 1 month before, in February
If one assumes that it was very smart, it obviously could have interpreted
the phases right between the invention of his scope and February 1610.
But that leaves him just a few weeks, and in counting on clear sky every
days, to discover the phases and its explanations, under bad seeing, without
speaking about his optics....

The book having been published in March, he would thus have observed Venus
at the worst moment of its phase Or he had to develop his scope in 1609...
But here also, the first drafts of Giovanni Battista della Porta were
published in August 1609... (to confirm as well). But that of Galileo would
not have been invented yet at that time.

That would tend to confirm that Galileo would have discovered the Venus
phases at a time it had a small diameter ( 15-12" if I remember well) under
very difficult conditions (both hardware and astronomical). The discovery
would all the more be deserving.
But is this well at that time that all that was held ?

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

Thanks in avdance

Thierry
http://www.astrosurf.org/lombry

Thierry wrote in message ...
Hello,

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...

Looks like the dates may be in error
Wikipedia
"Based only on sketchy descriptions of the telescope, invented in the
Netherlands in 1608, Galileo made one with about 8x magnification, and then
made improved models up to about 20x. On August 25, 1609, he demonstrated
his first telescope to Venetian lawmakers."
http://en.wikipedia.org/wiki/Galileo#Astronomy

If I simulate the sky at that time, of Firenze, arcetri, we discover that
in Jan-April 1610 Venus was in the East, 10° over the horizon with 80%+
illuminated, thus very small, and at the end in the rays of sun. hard to
imagine that he observed it at that time. It nevertheless could have did
it.
On the other hand, at the autumn 1609 venus shows a fine crescent, and was
higher in the sky of the morning

Good work, and could well suggest that he observed Venus in Autumn 1609
rather than early in 1610.

"OG" wrote in message
...

Thierry wrote in message ...
Hello,

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...

Looks like the dates may be in error
Wikipedia

Not sure that wikipedia is a formal source of information
It will be not the first time that i correct data because references or
commentaries are not accurate, mix with rumor, etc.
I am agree that there are a lot of good things on wikipedia, I work on it as
well, but I don't consider it as an official source.
better to go to the museum of science of firenze, don't you think...

Thierry

"Based only on sketchy descriptions of the telescope, invented in the
Netherlands in 1608, Galileo made one with about 8x magnification, and
then made improved models up to about 20x. On August 25, 1609, he
demonstrated his first telescope to Venetian lawmakers."
http://en.wikipedia.org/wiki/Galileo#Astronomy

If I simulate the sky at that time, of Firenze, arcetri, we discover that
in Jan-April 1610 Venus was in the East, 10° over the horizon with 80%+
illuminated, thus very small, and at the end in the rays of sun. hard to
imagine that he observed it at that time. It nevertheless could have did
it.
On the other hand, at the autumn 1609 venus shows a fine crescent, and
was higher in the sky of the morning

Good work, and could well suggest that he observed Venus in Autumn 1609
rather than early in 1610.

Thierry wrote in :


"OG" wrote in message
...

Thierry wrote in message ...
Hello,

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...

Looks like the dates may be in error
Wikipedia

Not sure that wikipedia is a formal source of information
It will be not the first time that i correct data because references or
commentaries are not accurate, mix with rumor, etc.
I am agree that there are a lot of good things on wikipedia, I work on
it as well, but I don't consider it as an official source.
better to go to the museum of science of firenze, don't you think...

Thierry

True but good Wikipedia articles should give references to primary sources.

Klazmon.



"Based only on sketchy descriptions of the telescope, invented in the
Netherlands in 1608, Galileo made one with about 8x magnification, and
then made improved models up to about 20x. On August 25, 1609, he
demonstrated his first telescope to Venetian lawmakers."
http://en.wikipedia.org/wiki/Galileo#Astronomy

If I simulate the sky at that time, of Firenze, arcetri, we discover
that in Jan-April 1610 Venus was in the East, 10° over the horizon
with 80%+ illuminated, thus very small, and at the end in the rays of
sun. hard to imagine that he observed it at that time. It nevertheless
could have did it.
On the other hand, at the autumn 1609 venus shows a fine crescent, and
was higher in the sky of the morning

Good work, and could well suggest that he observed Venus in Autumn 1609
rather than early in 1610.

"OG" wrote in message
...

Thierry wrote in message ...
Hello,

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...

Looks like the dates may be in error
Wikipedia
"Based only on sketchy descriptions of the telescope, invented in the
Netherlands in 1608, Galileo made one with about 8x magnification, and
then made improved models up to about 20x. On August 25, 1609, he
demonstrated his first telescope to Venetian lawmakers."

Right. My mistake. I reread , my notes (I always wonder of the number of
information i found on my own site and that I have forgotten, of almost).
Hopefully there is a search engine....
Galileo seems have demonstrated his scope already on August 21. Its
magnification was 3x.
Remain to confirm the first observation of venus and with what scope

Thierry

Thierry wrote:
snip.
Remain to confirm the first observation of venus and with what scope
Thierry

You might find these pages of interest in Pope's and Mosher's project -


WHAT GALILEO SAW
http://www.pacifier.com/~tpope/Photo...rison_Page.htm

VENUS THROUGH THE GALILEAN TELESCOPE
http://www.pacifier.com/~tpope/Venus_Page.htm

CCD IMAGES FROM A GALILEAN TELESCOPE
http://www.pacifier.com/~tpope/index.htm

- Canopus56

P.S. - Mosher and Pope note that the Venus drawings were first
reproduced in a plate in Galieo's _Il Saggiatore_ (1623). Mosher and
Pope also note that: "Galileo made many careful observations of the
phases of Venus, yet we do not know of any manuscript pages containing
the original drawings from which the plate was made."

Galileo may have made his Venus observations at anytime between 1610
and 1623.

It is also said that he invented his scope only in 1610

Heard that Galileo didn't invent the telescope, but was the first to
look at objects in the sky as a scientist. Others who had telescopes
for looking for ships and such probably took a peak at the Moon but
never did anything with those observations.

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...

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.

--
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

"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

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