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Home > Dictionary of Science Quotations > Scientist Names Index G > Galileo Galilei Quotes > Telescope

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Galileo Galilei
(15 Feb 1564 - 8 Jan 1642)

Italian natural philosopher who believed the Earth revolved around the Sun. For this, he was interrogated by the Inquisition, was put on trial, found guilty and sentenced to indefinite imprisonment. For renouncing his former beliefs before the Cardinals that judged him, he was allowed to serve this time instead under house-arrest.


Galileo Galilei Quotes on Telescope (8 quotes)

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About ten months ago [1609] a report reached my ears that a certain Fleming [Hans Lippershey] had constructed a spyglass, by means of which visible objects, though very distant from the eye of the observer, were distinctly seen as if nearby... Of this truly remarkable effect several experiences were related, to which some persons gave credence while others denied them. A few days later the report was confirmed to me in a letter from a noble Frenchman at Paris, Jacques Badovere, which caused me to apply myself wholeheartedly to enquire into the means by which I might arrive at the invention of a similar instrument. This I did shortly afterwards, my basis being the theory of refraction. First I prepared a tube of lead, at the ends of which I fitted two glass lenses, both plane on one side while on the other side one was spherically convex and the other concave.
— Galileo Galilei
The Starry Messenger (1610), trans. Stillman Drake, Discoveries and Opinions of Galileo (1957), 28-9.
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But that which will excite the greatest astonishment by far, and which indeed especially moved me to call the attention of all astronomers and philosophers, is this: namely, that I have observed four planets, neither known nor observed by any one of the astronomers before my time, which have their orbits round a certain bright star [Jupiter], one of those previously known, like Venus or Mercury round the sun, and are sometimes in front of it, sometimes behind it, though they never depart from it beyond certain limits. All of which facts were discovered and observed a few days ago by the help of a telescope devised by me, through God’s grace first enlightening my mind.
— Galileo Galilei
In pamphlet, The Sidereal Messenger (1610), reprinted in The Sidereal Messenger of Galileo Galilei: And a Part of the Preface to the Preface to Kepler's Dioptrics Containing the Original Account of Galileo's Astronomical Discoveries (1880), 9.
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I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury about the Sun; which at length was established as clear as daylight by numerous other observations.
Referring to his pioneering telescope observations.
— Galileo Galilei
The Starry Messenger (Mar 1610). Quoted in Edmund Blair Bolles, Galileo's Commandment (1999), 104.
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I wish, my dear Kepler, that we could have a good laugh together at the extraordinary stupidity of the mob. What do you think of the foremost philosophers of this University? In spite of my oft-repeated efforts and invitations, they have refused, with the obstinacy of a glutted adder, to look at the planets or the Moon or my glass [telescope].
— Galileo Galilei
Opere ed Nas. X, 423. As cited in Alan Mackay, A Dictionary of Scientific Quotations (1991), 99. Galileo wished others to use his telescope to see for themselves the moons of Jupiter which he had himself first seen in Jan 1610. If you have a primary source for this letter giving the date it was written, please contact Webmaster.
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Many of the nobles and senators, although of great age, mounted more than once to the top of the highest church in Venice, in order to see sails and shipping … so far off that it was two hours before they were seen without my spy-glass …, for the effect of my instrument is such that it makes an object fifty miles off appear as large as if it were only five miles away. ... The Senate, knowing the way in which I had served it for seventeen years at Padua, ... ordered my election to the professorship for life.
— Galileo Galilei
Quoted in Will Durant, Ariel Duran, The Age of Reason Begins (1961), 604. From Charles Singer, Studies in the History and Method of Science (1917), Vol. 1, 228.
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Oh, my dear Kepler, how I wish that we could have one hearty laugh together. Here, at Padua, is the principal professor of philosophy, whom I have repeatedly and urgently requested to look at the moon and planets through my glass, [telescope] which he pertinaciously refuses to do. Why are you not here? what shouts of laughter we should have at this glorious folly! and to hear the professor of philosophy at Pisa laboring before the grand duke with logical arguments, as if with magical incantations, to charm the new planets out of the sky.
— Galileo Galilei
From Letter to Johannes Kepler. As translated in John Elliot Drinkwater Bethune, Life of Galileo Galilei: With Illustrations of the Advancement of Experimental Philosophy (1832), 92-93.
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The next object which I have observed is the essence or substance of the Milky Way. By the aid of a telescope anyone may behold this in a manner which so distinctly appeals to the senses that all the disputes which have tormented philosophers through so many ages are exploded at once by the irrefragable evidence of our eyes, and we are freed from wordy disputes upon this subject, for the Galaxy is nothing else but a mass of innumerable stars planted together in clusters.
— Galileo Galilei
In pamphlet, The Sidereal Messenger (1610), reprinted in The Sidereal Messenger of Galileo Galilei: And a Part of the Preface to the Preface to Kepler's Dioptrics Containing the Original Account of Galileo's Astronomical Discoveries (1880), 42.
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The number of fixed stars which observers have been able to see without artificial powers of sight up to this day can be counted. It is therefore decidedly a great feat to add to their number, and to set distinctly before the eyes other stars in myriads, which have never been seen before, and which surpass the old, previously known stars in number more than ten times.
— Galileo Galilei
In pamphlet, The Sidereal Messenger (1610), reprinted in The Sidereal Messenger of Galileo Galilei: And a Part of the Preface to the Preface to Kepler's Dioptrics Containing the Original Account of Galileo's Astronomical Discoveries (1880), 7-8.
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See also:
  • 15 Feb - short biography, births, deaths and events on date of Galilei's birth.
  • Galileo - “And Yet It Moves” illustrated quote - Medium 500px
  • Galileo - “And Yet It Moves” illustrated quote - Large 800px
  • Galileo Galilei - Quotations - Abjuration
  • Galileo Gailei - biography from Famous Men of Science (1889).
  • Galileo: A Life, by James Reston. - book suggestion.
  • Booklist for Galileo Galilei.

Carl Sagan Thumbnail In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) -- Carl Sagan
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