Galileo Galilei, Florence, Italy, 1609
Convex objective lens and concave lens in a long tube
Museum of the History of the Science, Florence.
Galilei, Galileo. Galileo’s 20x Telescope. 1610. Convex objective lens and eyepiece in a long tube. Museum of the History of the Science, Florence. 3 December, 2018. https://blog.nationalgeographic.org/2011/05/25/brief-history-of-the-astronomical-telescope-i-galileo-galilei-and-the-unlikely-fate-of-his-middle-finger/
Provenance: Copy of telescope held by the Istituto e Museo di Storia della Scienzia, Florence One of a pair – see Inv 11094
The telescope was initially designed by the Dutch spectacles maker Hans Lippershey in 1608; he claimed to create a tool that magnified distant objects three times using a concave and convex lens. Its body was no more than two silver tubes fitted together, about seven inches long. The telescope obviously went on to be further developed into the monumentally valuable instrument we know today. The one pictured above, a model of Galileo’s 20X telescope, was created a year later in Florence, Italy. It used both a concave lens, serving as the eyepiece and one convex objective lens serving as the objective. These are on either end of a long tube, positioned so that they have the same focal points. It had a relatively small field of view compared to what we are used to in the modern telescope.
Because the telescope was created by a spectacles-maker, the original purpose was to magnify objects on Earth, not those in the sky. It was originally used for commercial purpose as a sort of amusing toy or tool for Enlightenment Europe to see what was originally far more difficult to perceive. Initially, it wasn’t even perceived as a potential tool for the military; clearly its untapped potential was exponential. Therefore, when Galileo pointed this new instrument towards the heavens, the effects and implications were monumental.
The telescope was one of the most important technological advancements of the European Enlightenment. Prior to its advent, scientists used tools such solar quadrants, armillary astrolabes, and parallactic instruments, all of which were considerably precise in measurements considering their context but did not provide nearly as much detail or information as the telescope. However, they were enough to provide solid theories off of which the astronomers with access to telescopes based much of their own ideas. The physical observations this tool provided held the potential to challenge the groundwork of all that society had known up until this point; never before had people been given the opportunity to see the world from a non-human centered point of view.
It was with this pre-telescopic equipment that Ptolemy and Copernicus developed their respective geocentric and heliocentric models of the universe. Following them was Tycho Brahe, a well-respected Danish nobleman, who also did not have access to the telescope and developed a model somewhere between Ptolemy and Copernicus’: one with an immobile Earth surrounded by a rotating moon and stars while the rest of the planets circled the sun. His student, Johannes Kepler, set about proving his instructor wrong by returning to Copernicus’ heliocentric model with the use of a telescope. Galileo additionally advanced and employed the telescope to support the heliocentric model, inciting his famous controversy with the Catholic Church.
Sources:
Graney, Christopher M. “Francesco Ingoli’s Essay To Galileo: Tycho Brahe and Science in the Inquisition’s Condemnation of the Copernican Theory” History and Philosophy of Physics, Cornell University Library (18 Nov 2012): 1-60.
Graney, Christopher M. “Of Mites and Men: Johannes Kepler on Stars and Size”. History and Philosophy of Physics, Cornell University Library (9 Feb 2018): 1-19.
Hollricher, Olaf and Wolfram Ibach. “High Resolution Optical and Confocal Microscopy.” Confocal Raman Microscopy Springer Series in Optical Sciences, August 31, 2010, 1-20.
Peterson, Mark A. Galileo’s Muse. Cambridge, Massachusetts: Harvard University Press, Oct 17, 2011.