History of the telescope
The history of the telescope can be traced to before the invention of the earliest known
Isaac Newton is credited with building the first reflector in 1668 with a design that incorporated a small flat diagonal mirror to reflect the light to an eyepiece mounted on the side of the telescope. Laurent Cassegrain in 1672 described the design of a reflector with a small convex secondary mirror to reflect light through a central hole in the main mirror.
The achromatic lens, which greatly reduced color aberrations in objective lenses and allowed for shorter and more functional telescopes, first appeared in a 1733 telescope made by Chester Moore Hall, who did not publicize it. John Dollond learned of Hall's invention[2][3] and began producing telescopes using it in commercial quantities, starting in 1758.
Important developments in reflecting telescopes were
During the period 1850–1900, reflectors suffered from problems with speculum metal mirrors, and a considerable number of "Great Refractors" were built from 60 cm to 1 metre aperture, culminating in the
.The era of
Optical telescopes
Optical foundations
Objects resembling
Actual use of lenses dates back to the widespread manufacture and use of
Invention
The first record of a telescope comes from the Netherlands in 1608. It is in a patent filed by
The original Dutch telescopes were composed of a
Claims of prior invention
In 1655 Dutch diplomat
In 1682,
A 1959 research paper by Simon de Guilleuma claimed that evidence he had uncovered pointed to the French born spectacle maker Juan Roget (died before 1624) as another possible builder of an early telescope that predated Hans Lippershey's patent application.[33]
In 2022 Italian Professor of Physics Alessandro Bettini published a paper on whether Leonardo da Vinci could have invented a telescope.[34] Building on 1939 observations by Domenico Argentieri of what look like lenses arranged like a telescope in da Vinci drawings, Bettini superimposed Argentieri's lens arrangement on an adjacent drawing of diverging rays, coming up with an arrangement that also looked like a telescope. Bettini also noted the writings of Italian scholar and professor Girolamo Fracastoro in 1538 about combining lenses in eyeglasses to make the "moon or at another star" "so near that they would appear not higher than the towers".[34]
Spread of the invention
Lippershey's application for a patent was mentioned at the end of a diplomatic report on an embassy to Holland from the Kingdom of Siam sent by the Siamese king Ekathotsarot: Ambassades du Roy de Siam envoyé à l'Excellence du Prince Maurice, arrivé à La Haye le 10 Septemb. 1608 (Embassy of the King of Siam sent to his Excellency Prince Maurice, arrived at The Hague on 10 September 1608). This report was issued in October 1608 and distributed across Europe, leading to experiments by other scientists, such as the Italian Paolo Sarpi, who received the report in November, and the English mathematician and astronomer Thomas Harriot, who used a six-powered telescope by the summer of 1609 to observe features on the moon.[35]
The Italian polymath
Galileo set himself to improving the telescope, producing telescopes of increased power. His first telescope had a 3x magnification, but he soon made instruments which magnified 8x and finally, one nearly a meter long with a 37mm objective (which he would stop down to 16mm or 12mm) and a 23x magnification.
Galileo's instrument was the first to be given the name "telescope". The name was invented by the Greek poet/theologian Giovanni Demisiani at a banquet held on April 14, 1611, by Prince Federico Cesi to make Galileo Galilei a member of the Accademia dei Lincei.[42] The word was created from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing'.
By 1626 knowledge of the telescope had spread to China when German Jesuit and astronomer Johann Adam Schall von Bell published Yuan jing shuo, (遠鏡說, Explanation of the Telescope) in Chinese and Latin.[43]
Further refinements
Refracting telescopes
The first powerful telescopes of Keplerian construction were made by
Long focal length refractors
The
Aerial telescopes
In some of the very long refracting telescopes constructed after 1675, no tube was employed at all. The objective was mounted on a swiveling ball-joint on top of a pole, tree, or any available tall structure and aimed by means of string or connecting rod. The eyepiece was handheld or mounted on a stand at the focus, and the image was found by trial and error. These were consequently termed
Reflecting telescopes
The ability of a
In 1636
In 1666
A third form of reflecting telescope, the "Cassegrain reflector" was devised in 1672 by Laurent Cassegrain. The telescope had a small convex hyperboloidal secondary mirror placed near the prime focus to reflect light through a central hole in the main mirror.
No further practical advance appears to have been made in the design or construction of the reflecting telescopes for another 50 years until John Hadley (best known as the inventor of the octant) developed ways to make precision aspheric and parabolic speculum metal mirrors. In 1721 he showed the first parabolic Newtonian reflector to the Royal Society.[60] It had a 6-inch (15 cm) diameter, 62+3⁄4-inch (159 cm) focal length speculum metal objective mirror. The instrument was examined by James Pound and James Bradley.[61] After remarking that Newton's telescope had lain neglected for fifty years, they stated that Hadley had sufficiently shown that the invention did not consist in bare theory. They compared its performance with that of a 7.5 inches (190 mm) diameter aerial telescope originally presented to the Royal Society by Constantijn Huygens, Jr. and found that Hadley's reflector, "will bear such a charge as to make it magnify the object as many times as the latter with its due charge", and that it represents objects as distinct, though not altogether so clear and bright.[62]
Bradley and Samuel Molyneux, having been instructed by Hadley in his methods of polishing speculum metal, succeeded in producing large reflecting telescopes of their own, one of which had a focal length of 8 ft (2.4 m). These methods of fabricating mirrors were passed on by Molyneux to two London opticians —Scarlet and Hearn— who started a business manufacturing telescopes.[63]
The British mathematician, optician
Since speculum metal mirror secondaries or diagonal mirrors greatly reduced the light that reached the eyepiece, several reflecting telescope designers tried to do away with them. In 1762 Mikhail Lomonosov presented a reflecting telescope before the Russian Academy of Sciences forum. It had its primary mirror tilted at four degrees to telescope's axis so the image could be viewed via an eyepiece mounted at the front of the telescope tube without the observer's head blocking the incoming light. This innovation was not published until 1827, so this type came to be called the Herschelian telescope after a similar design by William Herschel.[65]
About the year 1774 William Herschel (then a teacher of music in
In 1845
All of these larger reflectors suffered from the poor reflectivity and fast tarnishing nature of their speculum metal mirrors. This meant they need more than one mirror per telescope since mirrors had to be frequently removed and re-polished. This was time-consuming since the polishing process could change the curve of the mirror, so it usually had to be "re-figured" to the correct shape.
Achromatic refracting telescopes
From the time of the invention of the first refracting telescopes it was generally supposed that chromatic errors seen in lenses simply arose from errors in the spherical figure of their surfaces. Opticians tried to construct lenses of varying forms of curvature to correct these errors.[15] Isaac Newton discovered in 1666 that chromatic colors actually arose from the un-even refraction of light as it passed through the glass medium. This led opticians to experiment with lenses constructed of more than one type of glass in an attempt to canceling the errors produced by each type of glass. It was hoped that this would create an "achromatic lens"; a lens that would focus all colors to a single point, and produce instruments of much shorter focal length.
The first person who succeeded in making a practical achromatic refracting telescope was
Hall was a man of independent means and seems to have been careless of fame; at least he took no trouble to communicate his invention to the world. At a trial in Westminster Hall about the patent rights granted to
In 1747, Leonhard Euler sent to the Prussian Academy of Sciences a paper in which he tried to prove the possibility of correcting both the chromatic and the spherical aberration of a lens. Like Gregory and Hall, he argued that since the various humours of the human eye were so combined as to produce a perfect image, it should be possible by suitable combinations of lenses of different refracting media to construct a perfect telescope objective. Adopting a hypothetical law of the dispersion of differently colored rays of light, he proved analytically the possibility of constructing an achromatic objective composed of lenses of glass and water.[64]
All of Euler's efforts to produce an actual objective of this construction were fruitless—a failure which he attributed solely to the difficulty of procuring lenses that worked precisely to the requisite curves.
In 1754, Euler sent to the Berlin Academy a further paper in which starting from the hypothesis that light consists of vibrations excited in an elastic fluid by luminous bodies—and that the difference of color of light is due to the greater or lesser frequency of these vibrations in a given time— he deduced his previous results. He did not doubt the accuracy of Newton's experiments quoted by Dollond.[64]
Dollond did not reply to this, but soon afterwards he received an abstract of a paper by the Swedish mathematician and astronomer, Samuel Klingenstierna, which led him to doubt the accuracy of the results deduced by Newton on the dispersion of refracted light. Klingenstierna showed from purely geometrical considerations (fully appreciated by Dollond) that the results of Newton's experiments could not be brought into harmony with other universally accepted facts of refraction.[64]
As a practical man, Dollond at once put his doubts to the test of experiment: he confirmed the conclusions of Klingenstierna, discovered a difference far beyond his hopes in the refractive qualities of different kinds of glass with respect to the divergence of colors, and was thus rapidly led to the construction of lenses in which first the chromatic aberration—and afterwards—the spherical aberration were corrected.[64][69]
Dollond was aware of the conditions necessary for the attainment of achromatism in refracting telescopes, but relied on the accuracy of experiments made by Newton. His writings show that with the exception of his bravado, he would have arrived sooner at a discovery for which his mind was fully prepared. Dollond's paper recounts the successive steps by which he arrived at his discovery independently of Hall's earlier invention—and the logical processes by which these steps were suggested to his mind.[66]
In 1765 Peter Dollond (son of John Dollond) introduced the triple objective, which consisted of a combination of two convex lenses of crown glass with a concave flint lens between them. He made many telescopes of this kind.[66]
The difficulty of procuring disks of glass (especially of flint glass) of suitable purity and homogeneity limited the diameter and light gathering power of the lenses found in the achromatic telescope. It was in vain that the French Academy of Sciences offered prizes for large perfect disks of optical flint glass.[66]
The difficulties with the impractical metal mirrors of reflecting telescopes led to the construction of large refracting telescopes. By 1866 refracting telescopes had reached 18 inches (46 cm) in aperture with many larger "
Large reflecting telescopes
In 1856–57,
The beginning of the 20th century saw construction of the first of the "modern" large research reflectors, designed for precision photographic imaging and located at remote high altitude clear sky locations
Active and adaptive optics
The 1980s saw the introduction of two new technologies for building larger telescopes and improving image quality, known as active optics and adaptive optics. In active optics, an image analyser senses the aberrations of a star image a few times per minute, and a computer adjusts many support forces on the primary mirror and the location of the secondary mirror to maintain the optics in optimal shape and alignment. This is too slow to correct for atmospheric blurring effects, but enables the use of thin single mirrors up to 8 m diameter, or even larger segmented mirrors. This method was pioneered by the ESO New Technology Telescope in the late 1980s.
The 1990s saw a new generation of giant telescopes appear using active optics, beginning with the construction of the first of the two 10 m (390 in)
Adaptive optics uses a similar principle, but applying corrections several hundred times per second to compensate the effects of rapidly changing optical distortion due to the motion of turbulence in the Earth's atmosphere. Adaptive optics works by measuring the distortions in a wavefront and then compensating for them by rapid changes of actuators applied to a small deformable mirror or with a liquid crystal array filter. AO was first envisioned by Horace W. Babcock in 1953, but did not come into common usage in astronomical telescopes until advances in computer and detector technology during the 1990s made it possible to calculate the compensation needed in real time.[74] In adaptive optics, the high-speed corrections needed mean that a fairly bright star is needed very close to the target of interest (or an artificial star is created by a laser). Also, with a single star or laser the corrections are only effective over a very narrow field (tens of arcsec), and current systems operating on several 8-10m telescopes work mainly in near-infrared wavelengths for single-object observations.
Developments of adaptive optics include systems with multiple lasers over a wider corrected field, and/or working above kiloHertz rates for good correction at visible wavelengths; these are currently in progress but not yet in routine operation as of 2015.
Other wavelengths
The twentieth century saw the construction of telescopes which could produce images using wavelengths other than
Radio telescopes
Radio astronomy began in 1931 when
High-energy radio waves are known as
Because radio telescopes have low resolution, they were the first instruments to use
A telescope like the Large Millimeter Telescope (active since 2006) observes from 0.85 to 4 mm (850 to 4,000 μm), bridging between the far-infrared/submillimeter telescopes and longer wavelength radio telescopes including the microwave band from about 1 mm (1,000 μm) to 1,000 mm (1.0 m) in wavelength.
Infrared telescopes (700 nm/ 0.7 µm – 1000 µm/1 mm)
Although most
Ultra-violet telescopes (10 nm – 400 nm)
Although optical telescopes can image the near ultraviolet, the
X-ray telescopes (0.01 nm – 10 nm)
Gamma-ray telescopes (less than 0.01 nm)
Interferometric telescopes
In 1868,
The next major development came in 1946 when Ryle and Vonberg (Ryle and Vonberg 1946) located a number of new cosmic radio sources by constructing a radio analogue of the Michelson interferometer. The signals from two radio antennas were added electronically to produce interference. Ryle and Vonberg's telescope used the rotation of the Earth to scan the sky in one dimension. With the development of larger arrays and of computers which could rapidly perform the necessary Fourier transforms, the first aperture synthesis imaging instruments were soon developed which could obtain high resolution images without the need of a giant parabolic reflector to perform the Fourier transform. This technique is now used in most radio astronomy observations. Radio astronomers soon developed the mathematical methods to perform aperture synthesis Fourier imaging using much larger arrays of telescopes —often spread across more than one continent. In the 1980s, the aperture synthesis technique was extended to visible light as well as infrared astronomy, providing the first very high resolution optical and infrared images of nearby stars.
In 1995 this imaging technique was demonstrated on
In 2008,
See also
- 400 Years of the Telescope documentary
- History of astronomy
- Astronomical interferometer
- Timeline of telescope technology
- Timeline of telescopes, observatories, and observing technology
- International Year of Astronomy, 2009 marking the 400th anniversary of Galileo's first astronomical observations using his telescope
- List of optical telescopes
- List of largest optical refracting telescopes
- List of space telescopes
- List of telescope types
- Visible-light astronomy
References
- ISBN 978-0-486-43265-6
- ^ Lovell, D. J.; 'Optical anecdotes', pp.40-41
- ^ Wilson, Ray N.; 'Reflecting Telescope Optics: Basic design theory and its historical development', p.14
- ^ "Inventor Biographies – Jean-Bernard-Léon Foucault Biography (1819–1868)". madehow.com. Retrieved 2013-08-01.
- ^ "Bakich sample pages Chapter 2" (PDF). p. 3. Retrieved 2013-08-01.
John Donavan Strong, a young physicist at the California Institute of Technology, was one of the first to coat a mirror with aluminum. He did it by thermal vacuum evaporation. The first mirror he aluminized, in 1932, is the earliest known example of a telescope mirror coated by this technique.
- ^ ISBN 978-0-486-43265-6
- ^ "Perfecting the lens" (PDF). Retrieved 2013-08-01.
- S2CID 96668398.
- ^ Atti Della Fondazione Giorgio Ronchi E Contributi Dell'Istituto Nazionale Di Ottica, Volume 30, La Fondazione-1975, page 554
- ^ galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden
- ^ The History of the Telescope By Henry C. King, page 27, "(spectacles) invention, an important step in the history of the telescope"
- ^ Osservatorio Astronomico di Bologna - TELESCOPES
- ^ Osservatorio Astronomico di Bologna - TELESCOPES "The request however was turned down, also because other spectacle-makers had made similar claims at the same time."
- ^ "The Hague discussed the patent applications first of Hans Lipperhey of Middelburg, and then of Jacob Metius of Alkmaar... another citizen of Middelburg galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden
- ^ a b c d e f g h Taylor & Gill 1911, p. 559.
- ^ Dutch biologist and naturalist Pieter Harting claimed in 1858 that this shorter tube was an early microscope which he also attributed to Janssen, perpetuating the Janssen claim to both devices.
- ^ a b Albert Van Helden, Sven Dupré, Rob Van Gent, Huib Zuidervaart, The Origins of the Telescope, pages 32-36
- ISBN 978-90-6984-615-6.
- ^ King, Henry C. The History of the Telescope. Courier Dover Publications. 1955/2003.
- ISBN 978-90-6984-615-6.
- ISBN 978-90-6984-615-6.
- ^ Albert Van Helden, Sven Dupré, Rob van Gent, The Origins of the Telescope, Amsterdam University Press - 2010, pages 37-38
- ^ July 26, 1682
- ^ Peter D. Usher, Shakespeare and the Dawn of Modern Science, Cambria Press, 2010, page 28-29
- ^ Biographia Britannica: Or, The Lives of the Most Eminent Persons who Have Flourished in Great Britain and Ireland, from the Earliest Ages, Down to the Present Times, Volume 5, W. Innys - 1760, page 3130
- ^ Henry C. King, The History of the Telescope, Courier Corporation - 1955, page 28-29
- ^ a b Patrick Moore, Eyes on the Universe: The Story of the Telescope, Springer Science & Business Media - 2012, page 9
- ^ Satterthwaite, Gilbert (2002). "Did the reflecting telescope have English origins?". The Digges Telescope. Retrieved 25 January 2012.
- ^ Ronan, Colin A. (1991). "Leonard and Thomas Digges". Journal of the British Astronomical Association. 101 (6). Retrieved 25 January 2012.
- ISBN 9780306814839.
- ^ Fred Watson, (2007), Stargazer: The Life and Times of the Telescope, page 40. Allen & Unwin
- ^ Henry C. King, The History of the Telescope, Courier Corporation - 1955, page 28
- ^ "Controversy over telescope origin". BBC News. 16 September 2008. Retrieved 2009-07-06.
- ^ ISSN 1047-6938.
- ^ "Old Moon Map Corrects History". News.aol.com. 2009-01-14. Archived from the original on January 19, 2009. Retrieved 2013-08-01.
- ISBN 978-0-486-49542-2. Retrieved 2013-08-01.
- ^ Price, Derek deSolla (1982). On the Brink of Tomorrow: Frontiers of Science. Washington D.C.: National Geographic Society. p. 16.
- ^ a b adapted from the 1888 edition of the Encyclopædia Britannica.
- ^ Taylor & Gill 1911, pp. 558–559.
- ^ Jim Quinn, Stargazing with Early Astronomer Galileo Galilei, Sky & Telescope, July 31, 2008 [1]
- S2CID 117985979.
- ^ Rosen, Edward, The Naming of the Telescope (1947)
- ^ Schreier, Jeremy (4 June 2013). "Head-On Intersection of East and West: The Overlooked History of Galileo in China". Intersect: The Stanford Journal of Science, Technology, and Society. 6 (2).
- ^ a b Paul Schlyter. "Largest optical telescopes of the world". Stjarnhimlen.se. Retrieved 2013-08-01.
- ^ a b "The First Telescopes", Cosmic Journey: A History of Scientific Cosmology, Center for History of Physics, a Division of the American Institute of Physics
- ^ "How Telescopes Improved", History of Telescopes, Cartage, archived from the original on 2009-03-11
- ^ "The Telescope". Angelfire.com. Retrieved 2013-08-01.
- ISBN 978-0-486-43265-6
- S2CID 29596446
- ^ Reading Euclid by J. B. Calvert, 2000 Duke U. accessed 23 October 2007
- ISBN 978-1-74176-392-8. Retrieved 2013-08-01.
- ISBN 978-1-74176-392-8. Retrieved 2013-08-01.
- ^ [2] Mirror Mirror: A History of the Human Love Affair With Reflection by Mark Pendergrast Page 88
- ISBN 978-0-486-43265-6. Retrieved 2013-08-01.
- ^ Isaac Newton, Optics, bk. i. pt. ii. prop. 3
- ^ Treatise on Optics, p. 112
- ISBN 978-0-7382-0143-6. Retrieved 2013-08-01.
- ^ Isaac Newton: adventurer in thought, by Alfred Rupert Hall, page 67
- ^ "Reflecting telescopes: Newtonian, two- and three-mirror systems". Telescope-optics.net. Retrieved 2013-08-01.
- ^ "Hadley's Reflector". amazing-space.stsci.edu. Retrieved 2013-08-01.
- ^ Pound reported upon it in Phil. Trans., 1723, No. 378, p. 382.
- ^ Taylor & Gill 1911, pp. 559–560.
- ^ Smith, Robert, Compleat system of opticks in four books, bk, iii. ch. I. (Cambridge, 1738)
- ^ a b c d e f g h Taylor & Gill 1911, p. 560.
- ^ "On an optic pipe improvement" — Lomonosov M.V. Selected works in two volumes. Volume I: Natural sciences and philosophy. Moscow: Nauka (Science) publishing house, 1986 (in Russian). Name in Russian: «Об усовершенствовании зрительных труб» — М. В. Ломоносов. Избранные произведения. В двух томах. Т. 1. Естественные науки и философия. М.: Наука. 1986
- ^ a b c d Taylor & Gill 1911, p. 561.
- ^ Mem. Acad. Berlin, 1753.
- ^ Phil. Trans., 1753, p. 289
- ^ Phil. Trans., 1758, p. 733
- .
the largest telescope lens sag.
- ^ Mike Simmons (2008) [Written in 1984]. "Building the 60-inch Telescope". Mtwilson.edu. Archived from the original on 2013-08-05. Retrieved 2013-08-01.
- Bibcode:1956ASPL....7..249P.
- ^ "New Mexico Institute of Mining and Technology - "Resurfacing the 100-inch (2,500 mm) Telescope" by George Zamora". nmt.edu. Archived from the original on October 13, 2008. Retrieved 2013-08-01.
- ^ "Telescopes Have Grown from Huge to Humongous [Slide Show]". www.scientificamerican.com. Retrieved 2015-11-20.
Sources
- public domain: Taylor, Harold Dennis; Gill, David (1911). "Telescope". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 26 (11th ed.). Cambridge University Press. pp. 557–573. This article incorporates text from a publication now in the
- Crawford, David Livingstone, ed. (1966), The Construction of Large Telescopes (International Astronomical Union. Symposium no. 27 ed.), London, New York: Academic Press, p. 234
- Elliott, Robert S. (1966), Electromagnetics, McGraw-Hill
- Fizeau, H. 1868 C. R. Hebd. Seanc. Acad. Sci. Paris 66, 932
- King, Henry C., ed. (1955), The History of the Telescope, London: Charles Griffin & Co. Ltd
- Lindberg, D. C. (1976), Theories of Vision from al-Kindi to Kepler, Chicago: University of Chicago Press
- Michelson, A. A. 1891 Publ. Astron. Soc. Pac. 3, 274
- Michelson, A. A. & Pease, F. G. 1921 Astrophys. J. 53, 249
- Rashed, Roshdi; Morelon, Régis (1996), ISBN 0-415-12410-7
- Ryle, M. & Vonberg, D., 1946 Solar radiation on 175Mc/s, Nature 158 pp 339
- Wade, Nicholas J.; Finger, Stanley (2001), "The eye as an optical instrument: from camera obscura to Helmholtz's perspective", Perception, 30 (10): 1157–1177, S2CID 8185797
- Van Helden, Albert (1977), "The Invention of the Telescope", Transactions of the American Philosophical Society, Vol. 67, No. 4 – reprinted with corrections in 2008
- Van Helden, Albert; Dupré, Sven; van Gent, Rob & Zuidervaart, Huib, eds. (2010), The Origins of the Telescope, Amsterdam: KNAW Press [= History of Science and Scholarship in the Netherlands, vol. 12] pdf link
- Watson, Fred, ed. (2004), Star Gazer: The Life and History of the Telescope, Sydney, Cambridge: Allen & Unwin, Da Capo Press
External links
- History of optics articles
- History of telescope articles
- The Galileo Project – The Telescope by Al Van Helden
- 400th Anniversary of the Invention of the Telescope
- Articles on the history of the telescope and related subjects
- The Prehistory of the Invention of the Telescope
- A Brief History of the Telescope and Ideas for Use in the High School Physics Classroom
- A History Of The Telescope
- Physics 1040 – Beginning Astronomy – The Telescope
- An early history of the telescope – From 3500 B.C. until about 1900 A.D.
- Reflecting telescopes Historical Introduction – The Early Period (1608–1672)[permanent dead link]
- Other media
- Other possible telescope inventors
- Leonard Digges (1520–1559) Did the reflecting telescope have English origins? Leonard and Thomas Digges by Colin A Ronan, M.Sc., F.R.A.S. - originally published in the Journal of the British Astronomical Association, 101, 6, 1991
- Juan Roget (died before 1624) – Historian Nick Pelling says Juan Roget, a Burgundian spectacle maker who died between 1617 and 1624 could have invented an early telescope. Controversy over telescope origin – BBC News 16 September 2008