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#11
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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
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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
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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
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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
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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
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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
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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
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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
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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 |
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