The Telescope in Galileo’s Hands: the Expansion of the Universe, 1610

JF Ptak Science Books LLC  Post 672  Blog Bookstore

It bothers me how long people had access to something like a telescope and used it as a toy, or a contrivance, or as an insurance tool or a gear in the machine of war before the instrument made its ways into Galileo’s mind.  There are many rivalries for the term of “inventor” of the telescope, with descriptions of undoubtedly very primitive telescopes going back to Egyptian and Arabian legend, to Chaucer, to Roger Bacon’s “glasses or diaphanous bodies”, to the theoretical accomplishments of Thomas Digges and terrestrial interests of Dr. John Dee. These investigations no doubt made their influence in the development of the telescope, but seem minor compared to great strides made in 1608, when the telescope seemed to be everywhere (at least in Germany and Holland and Italy and France) in advanced development.  But particular high distinction goes to Holland, with Jan Lippershey  and James Metius  who (was it in 1608?) filed petitions for the exclusive rights to sell their instruments for seeing things at a distance. 

 

But still, people were still not actually pointing these instruments “up”—and then there was a class of aristocrats and well-do-dos who were shown these optical tools as toys and pastimes.  But all of this changed monumentally when news of the telescope came to Galileo’s attention in May 1609—by August 29 he had fabricated one of superior quality and effect (three diameters and nine times larger), though the first public demonstration was used to spot ships’ sails over an horizon that was invisible to the naked eye.  By 1610 he had produced his fifth and most powerful telescope, allowing things one thousand times closer, which he instantly used and made enormous discoveries of such significance that they are hard to understand today in the context of early 17^th century knowledge.

 With the exception of comets and eclipses the sky had remained immutable, a perfect score of the creator’s creation, until 1572, when Tycho Brahe noticed something new in Cassiopeia, something that was not a comet—a something that was a star. This was momentous because the night sky had been seen for centuries as being complete—a new star, the Nova of Brahe, contradicted this high belief, offering the possibilities of newness where there had not been one previously.  And so too with Kepler’s new star of 1602.

 

One of the things that Galileo brought to the world was an entirely new sky, revealed to him through his telescope—so many stars that he could only guess (though Galleon reckoned that there was an order of magnitude more stars than previously known “stars in myriads, which had never been seen before….and which surpasses the old, previously known, stars by ten times”).

 

All of this was published in his fantastic Sidereus Nuncius on March 4, 1610—extraordinarily, the very title page¹ of the book proclaiming some of the great discoveries of Galileo’s adventure.  Of course there was also his investigations of the Milky Way and the impossible discovery of four new “planets” (moons) around Jupiter, and the disruption of the happy belief in a smooth and luminous Moon. 

It is difficult today to estimate the impact Galileo’s innovation and the subsequent (and immediate) publication of Sidereus had on society.  The challenges to long-defined orthodoxy and the bending of theological constraints (though the church would have its turn on Galileo later); expanding the size and scope of the universe, applying mathematics to the study of physics, understanding the physics of motion, developing the telescope and the microscope and other precision physical instruments, are all such deeply important changes that it is difficult to resize them in terms of 21^st century advancement. 

1. The title page reads: “great and very wonderful spectacles, and offering them to the consideration of every one, but especially of philosophers and astronomers; which have been observed by Galileo Galilei … by the assistance of a perspective glass lately invented by him; namely, in the face of the moon, in innumerable fixed stars in the milky-way, in nebulous stars, but especially in four planets which revolve round Jupiter at different intervals and periods with a wonderful celerity.”

Comments

[Ray Girvan]

Ah! I knew this bookmark would be useful eventually: nice article on Galileo and the Moon at The Galileo Project ( http://galileo.rice.edu/sci/observations/moon.html )