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25/07/2016 The telescope has revolutionised science and astronomy. Who invented the telescope? Il telescopio rifrattore nella storia “There is no nation which has not claimed for itself the remarkable invention of the telescope: indeed, the French, Spanish, English, Italians, and Hollanders have all maintained that they did this.” Domenico Licchelli Scuola Estiva di Astronomia 2016 – 21 Luglio Pierre Borel, De vero telescopii inventore (1656) The use of a convex lens to form an enlarged/magnified image is discussed in Alhazen's Book of Optics (1021). Its translation into Latin from Arabic in the 12th century was instrumental to the invention of eyeglasses in 13th century Italy. In a sermon delivered on February 23, 1306, the Dominican friar Giordano da Pisa (ca. 1255–1311) wrote "It is not yet twenty years since there was found the art of making eyeglasses, which make for good vision” The genesis of the refractor telescope A refractor telescope is composed of at least two lenses. Lenses, whose name reflects their shape, have been known since Antiquity. At that time they were mostly used for decoration, but the Ancients remarked Giordano's colleague Friar Alessandro della Spina of Pisa (d. 1313) was soon making eyeglasses. The Ancient Chronicle of the Dominican Monastery of St. Catherine in Pisa records: "Eyeglasses, having first been made by someone else, who was unwilling to share them, he [Spina] made them and shared them with everyone with a cheerful and willing heart." their peculiar properties. Sénèque (4 BC- 65 AC) mentioned in his Naturales Quaestiones: “Everything that is seen through water is bigger. The letters, though small and pale, looks larger and clearer [when seen through] a sphere of glass filled with water.” One could also set paper on fire by using a small piece of polished glass. Such observations and studies continued throughout the Middle Ages with people like Alhazen, Grosseteste, and Bacon. Detail of a portrait of the Dominican Cardinal and renowned biblical scholar Hugh of Saint-Cher painted by Tommaso da Modena in 1352 The Glasses Apostle by Conrad von Soest (1403) Seated apostle holding lenses in position for reading. Detail from Death of the Virgin, by the Master of Heiligenkreuz, ca. 1430 1 25/07/2016 In 1538 the Italian scholar Girolamo Fracastoro (c. 1478-1553) wrote: “If someone looks through two eye-glasses, of which one is placed above the other, he shall see everything larger and more closely.” The first description of a spyglass is to be found in a letter from Giambattista della Porta, the Neapolitan polymath, whose Magia Naturalis of 1589, well known all over Europe, contained a tantalizing hint at what might be accomplished by a combination of a convex and concave lens: ”With a concave you shall see small things afar off, very clearly; with a convex, things neerer to be greater, but more obscurely: if you know how to fit them both together, you shall see both things afar off, and things neer hand, both greater and clearly.” Who invented the telescope? Who invented the telescope? The history of the dissemination of the telescope starts in Middelburg, with a letter of recommendation, dated 25 September 1608, in which the authorities of the Dutch Province of Zeeland wrote as follows to the States General, then the sovereign body of the young ‘Republic of the Seven United Dutch Provinces’ in The Hague: “The bearer of this letter declares to have [found] a certain art with which one can see all things very far away as if they were nearby, by means of sights of glasses, which he pretends to be a new invention”. Who invented the telescope? “A few days before the departure of Ambrogio de Spinola [negotiator for the Spanish sovereign] from The Hague a spectacle-maker from Middelburg, a humble and God-fearing man, presented to His Excellency [Count Maurits], Letter of recommendation for Hans Lipperhey, written by the ‘Gecommiteerde Raden’ of the province of Zeeland, dated 25 September 1608. certain glasses by means of which one can detect and see distinctly things The archives of the States General confirm that Lipperhey received 300 guilders for his device. The conditions stipulated that he would not make such a device for other parties and he was requested to improve the instrument by making it suitable for two eyes, and using rock crystal or glass of the very best quality for his lenses. despite the fact that these cities are distant from The Hague one-and-a- three or four miles removed from us as if we were seeing them from a hundred paces. From the Tower in The Hague, one clearly sees, with the said glasses the Clock of Delft and the windows of the Church of Leiden, half, and three-and-a-half hours by road, respectively.” Zoomers & Zuidervaart, Embassies 2 25/07/2016 Who invented the telescope? Who invented the telescope? In March 1609, the papal nuncius in Brussels, Guido Bentivoglio attended a “The said glasses are very useful in sieges and similar occasions, for from a mile or more away one can detect all heron hunt organised for the archduke just outside the gates of that city, in which one of these Brussels-made telescopes was tested. It amazed him how ‘miraculously’ the instrument performed, revealing details of a tower more than things as distinctly as if they were very close to us. And even ten miles away. Bentivoglio immediately ordered another copy to be made for the stars which ordinarily are invisible to our sight and Pope Paul V, which instrument arrived in Rome probably at the end of April our eyes, because of their smallness and the weakness of our sight, can be seen by means of this instrument.” Zoomers & Zuidervaart, Embassies 1609. Another telescope was presented in May 1609 in Milan, brought there by a Frenchman, who claimed to be an associate of the inventor from Holland. This person was possibly the same as the ‘foreigner’ who at the end of July 1609 demonstrated a telescope in Padua, where lived Paolo Sarpi, a friend of Galileo Galilei. Who invented the telescope? After seeing or hearing of Lipperhey’s telescope, many scholars had a kind of deja vu-feeling. Girolamo Sirtori, who in 1612, only four years after the emergence of the instrument, composed his well-known Telescopium, captured this feeling in the following phrase: “It appeared that this conception was in the minds of many men, so that once they heard about it, any ingenious person began trying to make one, without [the help of ] a model.” In the 1630s Sacharias Janssen’s son said that his father, who was a spectacle maker in Middelburg, and a colleague and Archduke Albertus of Austria, governor of the Southern Netherlands, observing a bird competitor of Lipperhey, built his first telescope years before 1609, with a telescope. Detail of a painting by Jan Brueghel the Elder, c. 1608-1611, following an Italian device dated 1590. However there is no representing the archduke in front of his castle Mariemont in Hanaut (Belgium). documentary evidence confirming this. 3 25/07/2016 Who invented the telescope? Thus, within a year of the demonstration in The Hague, the telescope was disseminated all over Europe, with the result that various European scholars had already used or at least examined the instrument. Before the end of 1609, telescopes were in the hands of Thomas Harriot in London, Galileo Galilei in Padua, Giovanbattista della Porta in Naples, Simon Marius in Gunzenhausen (Bavaria) and Rudolph Snellius in Leiden (Holland), to be followed the next year by Johannes Kepler in Prague), Christoph Scheiner in Ingolstadt (Bavaria), Nicolas Claude Fabri de Peiresc in Aix-en-Provence, Willebrord Snellius and Johann Fabricius, both in Leiden, and Sir William Lower in Carmarthenshire (Wales). In a letter to the founder of the Accademia dei Lincei, Prince Federico Cesi in Rome, dated 29 August 1609, Giambattista Della Porta made a sketch of an instrument that had just reached him, and he wrote: “About the secret of the spyglass [occhiale], I have seen it and it is a hoax [coglionaria], and taken from the ninth book of my De refractione.. It is a small tube of soldered silver, one palm in length, ad, and three fingerbreadths [diti] in diameter, which has a convex glass in the end, a. There is another tube of the same [material], 4 fingerbreadths long, which enters into the first one, and in the end b it has a concave [glass], which is secured like the first one. If observed with that first tube, faraway things areseen as if they were near, but because the vision does not occur along the perpendicular, they appear obscure and indistinct. When the other concave tube, which produces the opposite effect, is inserted, things will be seen clear and erect. And it goes in and out, as in a trombone, so that it adjusts to the eyesight of [particular] observers, which all differ”. Telescopes of Galileo Galilean telescope Characterized by the use of a negative (i.e., diverging) ocular (eyelens). In its simplest form, comprises only two lenses: the objective lens, which is plano-convex or biconvex, and the ocular, which is plano-concave or biconcave. The distance between the two lenses is equal to the difference between the absolute values of their focal lengths, and the magnifying power is given by the ratio of the focal lengths of the objective and the ocular. The advantage of the Galilean telescope is that is provides an upright image without requiring an erector-lens system. Its disadvantage is the extremely narrow field of view (moreover, in the Galilean design, the use of a diaphragm on the objective reduces not only brightness but also the field of view); far from being uniform, the brightness of the field of view gradually decreases from the center to the edge. Another drawback that spelled its rapid abandonment by astronomers is the impossibility of fitting the focal plane with a micrometer, i.e., a device for determining the angular size of the objects observed. 4 25/07/2016 n ( ) c v Keplerian telescope Characterized by the use of a positive (i.e., converging) ocular. In its simplest form, comprises only two plano-convex or biconvex lenses, one serving as the objective, the other as the ocular. To put it succinctly, the ocular functions as a magnifying lens that enlarges the (real) image formed by the objective. The distance between the two lenses is equal to the sum of their focal lengths, and the magnification is given by the ratio of the focal lengths of the objective and the ocular. The astronomical telescope produces upside-down images. This drawback can be eliminated by inserting an erector-lens system; it is largely offset by a somewhat broader and uniformly brighter field of view than the one offered by the Galilean telescope. Unlike the latter, the Keplerian design also allows the focal plane to be fitted with a micrometer, i.e., a device for determining the angular size of the objects observed. The Keplerian telescope totally replaced the Galilean model by the mid-seventeenth century. The instrument is also known as "Keplerian" because its optical arrangement was first described by Johannes Kepler (1571-1630) in his Dioptrice, published in Prague in 1611 All the telescopes used by Galileo are believed to have used plano-concave eyepieces. When such a lens is placed inside the prime focus by its own focal length, f, the effect is as shown: OTTICA PERFETTA Aberrazione cromatica Aberrazione sferica Astigmatismo The following diagram illustrates the effect of using a positive eye lens with identical focal length and diameter to that in the previous example: Cromatica + sferica + astigmatismo 5 25/07/2016 John Dollond The large images was photographed with the positive eyepiece. A 16 mm diameter baffle close to the prime focus limits the field to 55 arc minutes. The small images shows, to the same scale, the small portion of the Keplerian view visible at any one time with a negative eyepiece of the same focal length. The full diameter of the Galilean field, which is unaffected by the baffle, is 14 arc minutes. Left: A reference picture of the insulator on the phone pole taken with the Celestron C8 and reduced to the scale of the Galilean photos. Center: Detail from the center of a Galilean photograph showing the same insulator as seen through the 23 mm refractor with its negative eyepiece. Right: The Celestron and positive eyepiece images have Detail from the center of photograph been inverted and rotated to match the Galilean view. taken with the positive eyepiece using the same camera settings. The primary limitation of the image quality that was produced with early telescopes was chromatic aberration of the objective lens. Because of the color dispersion of the glass in a simple objective lens, different wavelengths have different focal lengths and are brought to focus at different distances. Achromatic objectives correct chromatic aberration by combining a positive lens made from a low-dispersion glass with a negative lens made from a high-dispersion glass. The original inventor of the achromatic objective is Chester Moor. In 1733 he commissioned two different opticians, Edward Scarlett and James Mann, to each make one of the lens elements. By chance, both opticians subcontracted the work to the same man, George Bass. Chester Moor Hall then continued to keep his invention secret. Around 1750, Bass told optician John Dollond about the achromatic lens he had made. Dollond’s son, Peter, saw the commercial advantages and once they had made test lenses, patented the invention in 1758. Chester Moor Hall twice attempted to challenge the patent. Dollond Telescope with Tripod Signature Date Dimensions Main Tube Length Main Tube Diameter Total Length Closed Length Objective Clear Aperture Diameter Dollond, London Circa 1800 Metric 265mm 56mm 1055mm 195mm 52mm 6 25/07/2016 Joseph von Fraunhofer “I stood astonished before this beautiful instrument, undetermined which to admire most, the beauty and elegance of the workmanship in its minute parts, the propriety of its construction, the ingenious mechanism for moving it, or the incomparable optical power of the telescope and the precision with which objects are defined……What a difference is seen there! A mountain peak illuminated on the dark side of the Moon, which offers me noting remarkable in the Troughton (refractor), I recognize, by means of the Giant Refractor as consisting of 6 peaks well separated from each other. One of the most difficult of Herschel’s double stars I recognize immediately. I believe this telescope can be boldly placed alongside the giant reflecting telescope of a Herschel, for if the latter has a greater light-gathering power, our achromat surpasses by far any reflecting telescope in the precision of the images (…) By clockwork the telescope can be given a uniform motion similar to the velocity of the fixed stars, so that the star remains in the field of view.” Percival Lowell F.G. Wilhelm Struve The 77-centimetre (30 in) refractor at Nice Observatory, when built the world's largest, longest, and highest refracting telescope On the night of January 31st, 1862, Alvan Clark and his son, Alvan Graham Clark, were testing a lens for a new telescope18and-a-half inches in diameter. To test it, the Clarks turned it toward Sirius, the brightest star in the night sky. Within moments, the younger Clark discovered that the star had a companion — a dot so faint and so close to Sirius itself that it had never been seen through the star’s glare. The companion had been predicted by German astronomer Friedrich Bessel who noticed small odd irregularities in the proper motions of the star. The 65 cm Zeiss (25.59 inches) achromatic refractor of Pulkovo observatory. The 30 inch (76 cm) refractor on the right, installed in 1885, was one of the largest telescopes in the world at that time The success of Clark’s lenses was attributed to skilful manipulation and supervision rather than the use of precise mechanisms. Clarks regularly retouched all four surfaces of each objective. This maybe the explanation for the superior quality of the Clarks object glasses. 7 25/07/2016 D=100mm Diffraction limit to resolution of two point-object images in incoherent light is approached when the two are of D=30mm near equal, optimum intensity. As the two PSF merge closer, the intensity deep between them diminishes. At the center separation of half the Airy disc diameter - 1.22λ/D radians (138/D in arc seconds, for λ=0.55μ and the aperture diameter D in mm), known as Rayleigh limit - the deep is at nearly 3/4 of the peak intensity. This refractor is still the largest in the world today. The combined weight of the two components of the 40-inch objective was 225 kg “From these tests it appears that the character of the image varies with the position of the lenses relative to each other, and, to a less extent, with the position of the objective as a whole relatively to its cell. It is probable that flexure of the lenses is the principal cause of the observed changes, and it is interesting to note that there is here evidence, for the first time, that we are approaching the limit of size in the construction of great objectives”. James Edward Keeler - 1896 Takahashi FET-200 Fluorite ED Triplet on EM-3500 Mount $165,480.00 Takahashi FSQ-130ED Super APO $12,795.00 8 25/07/2016 In 1856-57, Karl August von Steinheil and Léon Foucault introduced a process of depositing a layer of silver on glass telescope mirrors. The silver layer was not only much more reflective and longer lasting than the finish on speculum mirrors, it had the advantage of being able to be removed and re-deposited without changing the shape of the glass substrate. Towards the end of the 19th century very large silver on glass mirror reflecting telescopes were built. The beginning of the 20th century saw construction of the first of the "modern" large research reflectors, designed for precision photographic imaging such as the 60inch Hale telescope of 1908, and the 100-inch (2.5 m) Hooker telescope in 1917. 1948 saw the completion of the 200-inch (510 cm) Hale reflector at Mount Giornale di Fisica. Chimica e storia naturale ossia Raccolte di Memorie sulle Scienze, Arti e Manifatture ad esse relative di Luigi Brugnatelli. - Pavia, Tipogr. Capelli 1808-1827 Palomar which was the largest telescope in the world 9 25/07/2016 Galileoscope (+ webcam) in action – Moon and Planets Galileoscope in action – M45, The Pleiades 10 25/07/2016 Bibliography • Chapman A., A new perceived reality – Thomas Harriot’s Moon maps, Astronomy & Geophysics, vol 50, p1.27 (2009) • King H.C., History of telescope, 1955, Sky Publishing Corp. • Rosen E., Did Galileo claim he invented the telescope ?, Proceedings of the American Philosophical Society, vol 98, p304 (1954) • Rosen E., The invention of eyeglasses, Journal of the History of Medicine, vol 11, p13 & p183 (1956) • Van Helden A., The invention of the telescope, Transactions of the American Philosophical Society, vol 67, #4 (1977) • Wilson R., Reflecting Telescope Optics I & II, 1996 & 1999, Springer • V. Greco, G. Molesini, and F. Quercioli, "Optical tests of Galileo's lenses," Nature (London) 358, 101 (1992). • V. Greco, G. Molesini, and F. Quercioli, "Telescopes of Galileo," Applied Optics 32, 6219-6226 (1993). • G. Molesini, "The Telescopes of Seventeenth Century Italy," Optics & Photonics News (June 2003) 35-39. • The History of Telescopes and Binoculars: An Engineering Perspective - John E. Greivenkamp∗ and David L. Steed • Galilean Telescope Homepage • History of the telescope • Museo Galileo http://catalogue.museogalileo.it/index.html 1609 Galileoscope in action – M42, The Great Orion Nebula 11