For other uses, see Telescope (disambiguation). The 100 inch (2.54 m) Hooker reflecting telescope at Mount Wilson Observatory near Los Angeles, USA. A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands at the beginning of the 17th century, by using glass lenses.
They found use in both terrestrial applications and astronomy. Within a few decades, the reflecting telescope was invented, which used mirrors to collect and focus the light. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. The word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
The word telescope (from the Ancient Greek τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos "far-seeing") was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei. In the Starry Messenger, Galileo had used the term perspicillum. History Main article: History of the telescope The "onion" dome at the Royal Observatory, Greenwich housing a 28-inch refracting telescope with a remaining segment of William Herschel's 120-centimetre (47 in) diameter reflecting telescope (called the "40-foot telescope" due to its focal length) in the foreground.
The earliest existing record of a telescope was a 1608 patent submitted to the government in the Netherlands by Middelburg spectacle maker Hans Lippershey for a refracting telescope. The actual inventor is unknown but word of it spread through Europe. Galileo heard about it and, in 1609, built his own version, and made his telescopic observations of celestial objects. The idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope.
 The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs and several attempts to build reflecting telescopes. In 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector. The invention of the achromatic lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes.
Reflecting telescopes, though not limited by the color problems seen in refractors, were hampered by the use of fast tarnishing speculum metal mirrors employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857, and aluminized mirrors in 1932. The maximum physical size limit for refracting telescopes is about 1 meter (40 inches), dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors.
The largest reflecting telescopes currently have objectives larger than 10 m (33 feet), and work is underway on several 30-40m designs. The 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937. Since then, a large variety of complex astronomical instruments have been developed.
Types The primary mirror assembly of James Webb Space Telescope under construction. This is a segmented mirror and its coated with Gold to reflect (orange-red) visible light, through near-infrared to the mid-infrared The name "telescope" covers a wide range of instruments. Most detect electromagnetic radiation, but there are major differences in how astronomers must go about collecting light (electromagnetic radiation) in different frequency bands.
Telescopes may be classified by the wavelengths of light they detect: X-ray telescopes, using shorter wavelengths than ultraviolet light Ultraviolet telescopes, using shorter wavelengths than visible light Optical telescopes, using visible light Infrared telescopes, using longer wavelengths than visible light Submillimetre telescopes, using longer wavelengths than infrared light Fresnel Imager, an optical lens technology X-ray optics, optics for certain X-ray wavelengths As wavelengths become longer, it becomes easier to use antenna technology to interact with electromagnetic radiation (although it is possible to make very tiny antenna).
The near-infrared can be collected much like visible light, however in the far-infrared and submillimetre range, telescopes can operate more like a radio telescope. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm (0.003 mm) to 2000 μm (2 mm), but uses a parabolic aluminum antenna. On the other hand, the Spitzer Space Telescope, observing from about 3 μm (0.
003 mm) to 180 μm (0.18 mm) uses a mirror (reflecting optics). Also using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the frequency range from about 0.2 μm (0.0002 mm) to 1.7 μm (0.0017 mm) (from ultra-violet to infrared light). With photons of the shorter wavelengths, with the higher frequencies, glancing-incident optics, rather than fully reflecting optics are used.
Telescopes such as TRACE and SOHO use special mirrors to reflect Extreme ultraviolet, producing higher resolution and brighter images than are otherwise possible. A larger aperture does not just mean that more light is collected, it also enables a finer angular resolution. Telescopes may also be classified by location: ground telescope, space telescope, or flying telescope. They may also be classified by whether they are operated by professional astronomers or amateur astronomers.
A vehicle or permanent campus containing one or more telescopes or other instruments is called an observatory. Modern telescopes typically use CCDs instead of film for recording images. This is the sensor array in the Kepler spacecraft. Light Comparison Name Wavelength Frequency (Hz) Photon Energy (eV) Gamma ray less than 0.01 nm more than 10 EHZ 100 keV – 300+ GeV X X-Ray 0.01 to 10 nm 30 EHz – 30 PHZ 120 eV to 120 keV X Ultraviolet 10 nm – 400 nm 30 PHZ – 790 THz 3 eV to 124 eV Visible 390 nm – 750 nm 790 THz – 405 THz 1.
7 eV – 3.3 eV X Infrared 750 nm – 1 mm 405 THz – 300 GHz 1.24 meV – 1.7 eV X Microwave 1 mm – 1 meter 300 GHz – 300 MHz 1.24 meV – 1.24 µeV Radio 1 mm – km 300 GHz – 3 Hz 1.24 meV – 12.4 feV X Optical telescopes 50 cm refracting telescope at Nice Observatory. Main article: Optical telescope An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet).
 Optical telescopes increase the apparent angular size of distant objects as well as their apparent brightness. In order for the image to be observed, photographed, studied, and sent to a computer, telescopes work by employing one or more curved optical elements, usually made from glass lenses and/or mirrors, to gather light and other electromagnetic radiation to bring that light or radiation to a focal point.
Optical telescopes are used for astronomy and in many non-astronomical instruments, including: theodolites (including transits), spotting scopes, monoculars, binoculars, camera lenses, and spyglasses. There are three main optical types: The refracting telescope which uses lenses to form an image. The reflecting telescope which uses an arrangement of mirrors to form an image. The catadioptric telescope which uses mirrors combined with lenses to form an image.
Beyond these basic optical types there are many sub-types of varying optical design classified by the task they perform such as astrographs, comet seekers and solar telescopes. Radio telescopes The Very Large Array at Socorro, New Mexico, United States. Main article: Radio telescope Radio telescopes are directional radio antennas used for radio astronomy. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed.
Multi-element Radio telescopes are constructed from pairs or larger groups of these dishes to synthesize large 'virtual' apertures that are similar in size to the separation between the telescopes; this process is known as aperture synthesis. As of 2005, the current record array size is many times the width of the Earth—utilizing space-based Very Long Baseline Interferometry (VLBI) telescopes such as the Japanese HALCA (Highly Advanced Laboratory for Communications and Astronomy) VSOP (VLBI Space Observatory Program) satellite.
Aperture synthesis is now also being applied to optical telescopes using optical interferometers (arrays of optical telescopes) and aperture masking interferometry at single reflecting telescopes. Radio telescopes are also used to collect microwave radiation, which is used to collect radiation when any visible light is obstructed or faint, such as from quasars. Some radio telescopes are used by programs such as SETI and the Arecibo Observatory to search for extraterrestrial life.
X-ray telescopes Einstein Observatory was a space-based focusing optical X-ray telescope from 1978. Main article: X-ray telescope X-ray telescopes can use X-ray optics, such as a Wolter telescopes composed of ring-shaped 'glancing' mirrors made of heavy metals that are able to reflect the rays just a few degrees. The mirrors are usually a section of a rotated parabola and a hyperbola, or ellipse.
In 1952, Hans Wolter outlined 3 ways a telescope could be built using only this kind of mirror. Examples of an observatory using this type of telescope are the Einstein Observatory, ROSAT, and the Chandra X-Ray Observatory. By 2010, Wolter focusing X-ray telescopes are possible up to 79 keV. Gamma-ray telescopes Higher energy X-ray and Gamma-ray telescopes refrain from focusing completely and use coded aperture masks: the patterns of the shadow the mask creates can be reconstructed to form an image.
X-ray and Gamma-ray telescopes are usually on Earth-orbiting satellites or high-flying balloons since the Earth's atmosphere is opaque to this part of the electromagnetic spectrum. However, high energy X-rays and gamma-rays do not form an image in the same way as telescopes at visible wavelengths. An example of this type of telescope is the Fermi Gamma-ray Space Telescope. The detection of very high energy gamma rays, with shorter wavelength and higher frequency than regular gamma rays, requires further specialization.
An example of this type of observatory is VERITAS. Very high energy gamma-rays are still photons, like visible light, whereas cosmic rays includes particles like electrons, protons, and heavier nuclei. A discovery in 2012 may allow focusing gamma-ray telescopes. At photon energies greater than 700 keV, the index of refraction starts to increase again. High-energy particle telescopes High-energy astronomy requires specialized telescopes to make observations since most of these particles go through most metals and glasses.
In other types of high energy particle telescopes there is no image-forming optical system. Cosmic-ray telescopes usually consist of an array of different detector types spread out over a large area. A Neutrino telescope consists of a large mass of water or ice, surrounded by an array of sensitive light detectors known as photomultiplier tubes. Originating direction of the neutrinos is determined by reconstructing the path of secondary particles scattered by neutrino impacts, from their interaction with multiple detectors.
Energetic neutral atom observatories like Interstellar Boundary Explorer detect particles traveling at certain energies. Other types of telescopes Equatorial-mounted Keplerian telescope Astronomy is not limited to using electromagnetic radiation. Additional information can be obtained using other media. The detectors used to observe the Universe are analogous to telescopes. These are: Gravitational-wave detector, the equivalent of a gravitational wave telescope, used for gravitational-wave astronomy.
Neutrino detector, the equivalent of a neutrino telescope, used for neutrino astronomy. Types of mount Main article: Telescope mount A telescope mount is a mechanical structure which supports a telescope. Telescope mounts are designed to support the mass of the telescope and allow for accurate pointing of the instrument. Many sorts of mounts have been developed over the years, with the majority of effort being put into systems that can track the motion of the stars as the Earth rotates.
The two main types of tracking mount are: Altazimuth mount Equatorial mount Atmospheric electromagnetic opacity See also: Airmass Since the atmosphere is opaque for most of the electromagnetic spectrum, only a few bands can be observed from the Earth's surface. These bands are visible – near-infrared and a portion of the radio-wave part of the spectrum. For this reason there are no X-ray or far-infrared ground-based telescopes as these have to be observed from orbit.
Even if a wavelength is observable from the ground, it might still be advantageous to place a telescope on a satellite due to astronomical seeing. A diagram of the electromagnetic spectrum with the Earth's atmospheric transmittance (or opacity) and the types of telescopes used to image parts of the spectrum. Telescopic image from different telescope types Different types of telescope, operating in different wavelength bands, provide different information about the same object.
Together they provide a more comprehensive understanding. A 6′ wide view of the Crab nebula supernova remnant, viewed at different wavelengths of light by various telescopes By spectrum Telescopes that operate in the electromagnetic spectrum: Name Telescope Astronomy Wavelength Radio Radio telescope Radio astronomy (Radar astronomy) more than 1 mm Submillimetre Submillimetre telescopes* Submillimetre astronomy 0.
1 mm – 1 mm Far Infrared – Far-infrared astronomy 30 µm – 450 µm Infrared Infrared telescope Infrared astronomy 700 nm – 1 mm Visible Visible spectrum telescopes Visible-light astronomy 400 nm – 700 nm Ultraviolet Ultraviolet telescopes* Ultraviolet astronomy 10 nm – 400 nm X-ray X-ray telescope X-ray astronomy 0.01 nm – 10 nm Gamma-ray – Gamma-ray astronomy less than 0.
01 nm *Links to categories. Lists of telescopes List of optical telescopes List of largest optical reflecting telescopes List of largest optical refracting telescopes List of largest optical telescopes historically List of radio telescopes List of solar telescopes List of space observatories List of telescope parts and construction List of telescope types Category:Telescopes Category:Cosmic-ray telescopes Category:Gamma-ray telescopes Category:Gravitational wave telescopes Category:High energy particle telescopes Category:Infrared telescopes Category:Submillimetre telescopes Category:Ultraviolet telescopes Category:X-ray telescopes See also Airmass Amateur telescope making Angular resolution ASCOM open standards for computer control of telescopes Bahtinov mask Bioptic telescope Carey mask Dew shield Dynameter f-number First light GoTo telescope Hartmann mask Keyhole problem Microscope Remote Telescope Markup Language Robotic telescope Timeline of telescope technology Timeline of telescopes, observatories, and observing technology References ^ Sobel (2000, p.
43), Drake (1978, p.196) ^ Rosen, Edward, The Naming of the Telescope (1947) ^ galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden: The Hague discussed the patent applications first of Hans Lipperhey of Middelburg, and then of Jacob Metius of Alkmaar... another citizen of Middelburg, Zacharias Janssen is sometimes associated with the invention ^ "NASA - Telescope History".
www.nasa.gov. ^ Loker, Aleck (20 November 2017). "Profiles in Colonial History". Aleck Loker – via Google Books. ^ Watson, Fred (20 November 2017). "Stargazer: The Life and Times of the Telescope". Allen & Unwin – via Google Books. ^ Attempts by Niccolò Zucchi and James Gregory and theoretical designs by Bonaventura Cavalieri, Marin Mersenne, and Gregory among others ^ "Jean-Bernard-Léon Foucault Biography (1819-1868)".
www.madehow.com. ^ "Home" (PDF). Cambridge University Press. ^ ASTROLab du parc national du Mont-Mégantic. "The James-Clerk-Maxwell Observatory". Canada under the stars. Retrieved 2017-04-16. ^ "Hubble's Instruments: WFC3 - Wide Field Camera 3". www.spacetelescope.org. Retrieved 2017-04-16. ^ Jones, Barrie W. (2 September 2008). The Search for Life Continued: Planets Around Other Stars. Springer Science & Business Media.
ISBN 9780387765594. ^ a b "NuStar: Instrumentation: Optics". Archived from the original on 2010-11-01. ^ Wolter, H. (1952), "Glancing Incidence Mirror Systems as Imaging Optics for X-rays", Annalen der Physik, 10: 94, Bibcode:1952AnP...445...94W, doi:10.1002/andp.19524450108. ^ Wolter, H. (1952), "Verallgemeinerte Schwarzschildsche Spiegelsysteme streifender Reflexion als Optiken für Röntgenstrahlen", Annalen der Physik, 10 (4–5): 286, Bibcode:1952AnP.
..445..286W, doi:10.1002/andp.19524450410. ^ a b Tim Wogan – Silicon 'prism' bends gamma rays (May 2012) – PhysicsWorld.com Sources Contemporary Astronomy – Second Edition, Jay M. Pasachoff, Saunders Colleges Publishing – 1981, ISBN 0-03-057861-2 Elliott, Robert S. (1966), Electromagnetics, McGraw-Hill Rashed, Roshdi; Morelon, Régis (1996), Encyclopedia of the History of Arabic Science, 1 & 3, Routledge, ISBN 0-415-12410-7 Wade, Nicholas J.
; Finger, Stanley (2001), "The eye as an optical instrument: from camera obscura to Helmholtz's perspective", Perception, 30 (10): 1157–1177, doi:10.1068/p3210, PMID 11721819 Sabra, A. I.; Hogendijk, J. P. (2003). The Enterprise of Science in Islam: New Perspectives. MIT Press. pp. 85–118. ISBN 0-262-19482-1. External links Wikiquote has quotations related to: Telescope Wikimedia Commons has media related to Telescope.
Galileo to Gamma Cephei – The History of the Telescope The Galileo Project – The Telescope by Al Van Helden "The First Telescopes". Part of an exhibit from Cosmic Journey: A History of Scientific Cosmology by the American Institute of Physics Taylor, Harold Dennis; Gill, David (1911). "Telescope". Encyclopædia Britannica. 26 (11th ed.). pp. 557–573. Outside the Optical: Other Kinds of Telescopes Gray, Meghan; Merrifield, Michael (2009).
"Telescope Diameter". Sixty Symbols. Brady Haran for the University of Nottingham. Authority control NDL: 00560817 Retrieved from "https://en.wikipedia.org/w/index.php?title=Telescope&oldid=822368701"See Also: First National Bank Savings Account
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Hans Lippershey (1570 - September 1619), was born in western Germany, but re-settled in Middelburg in the Netherlands in 1594, marrying the same year and becoming a Dutch citizen in 1602. Lippershey was a lens maker, often credited as being the inventor of the telescope, being the first person to create and disseminate the designs for the first practical telescope. However, like the invention of the microscope, there is some debate as to who invented telescope.
The practical exploitation of the instrument was certainly achieved and came to public attention in the Netherlands at about 1608, but the credit of the original invention has been claimed on behalf of three individuals: Hans Lippershey and Zacharias Jansen, and Jacob Metius. Telescope history Some telescopes and spyglasses may have been created much earlier, but Lippershey is believed to be the first to apply for a patent for his design, a few weeks before Jacob Metius (a Dutch instrument maker and optician), and making it available for general use in 1608.
Although he failed to receive a patent, he was handsomely rewarded by the Dutch government for copies of his design. The telescope invented by Lippershey had a magnification of just 3x. However, although the invention of the telescope is generally credited to Lippershey, there is some evidence, that the principles of telescopes were known in the late 16th century. Did Hans Lippershey invent the microscope? Both Lippershey and Jansen lived in Middelburg in the Netherlands and whilst Lippershey is generally credited with inventing the telescope, Jansen is credited for inventing the microscope.
Although Zacharias Jansen may stake a more legitimate claim to have invented the telescope, Lippershey's role in the invention of the microscope is more questionable. The Dutch diplomat William Boreel, who was apparently an acquaintance of both Jansen and Lippershey in Middleburg during his youth, claimed that Lippershey stole his ideas from Jansen. Scholars generally argue, however, that Boreel was only being overzealous in his support of Jansen and that there is no real evidence that Lippershey did not develop his work independently.
What is clear is that around the early 17th century, both Zacharias Jansen and Hans Lippershey had been making optical instruments in the same Dutch city. Perhaps it is fair that Zacharias Jansen is more often credited with the invention of the microscope and Hans Lippershey with the invention of the telescope, since both appear to have made contributions to the development of both instruments. Galileo's telescope The original Dutch telescopes were composed of a convex and a concave lens, as this construction did not invert the image.
Lippershey's original design had only a 3x magnification, which was improved by Galileo the following year. Galileo had heard of the "Dutch perspective glass" by means of which distant objects appeared nearer and larger and states that he solved the problem of the construction of a telescope in one night. A few days afterwards, having succeeded in making a better telescope than the first, he took it to Venice where he communicated the details of his invention to the public and presented the instrument itself to the Senate.
Galileo may thus claim to have invented the telescope independently, although Galileo's immense improvement of the instrument overshadowed to a great degree the credit due to Lippershey as the original inventor.