Difference between revisions of "Telescopes"

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==Etymology==
 
==Etymology==
 
New Latin telescopium, from [[Greek]] tēleskopos  farseeing, from tēle- tele- + skopos watcher; akin to Greek skopein to look  
 
New Latin telescopium, from [[Greek]] tēleskopos  farseeing, from tēle- tele- + skopos watcher; akin to Greek skopein to look  
*Date: [http://www.wikipedia.org/wiki/17th_Century 1648]
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*Date: [https://www.wikipedia.org/wiki/17th_Century 1648]
 
==Definitions==
 
==Definitions==
 
*1 : a usually tubular [[optical]] instrument for viewing distant objects by means of the [[refraction]] of [[light]] rays through a [[lens]] or the [[reflection]] of [[light]] [[rays]] by a concave [[mirror]]  
 
*1 : a usually tubular [[optical]] instrument for viewing distant objects by means of the [[refraction]] of [[light]] rays through a [[lens]] or the [[reflection]] of [[light]] [[rays]] by a concave [[mirror]]  
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A '''telescope''' is an instrument [[designed]] for the [[observation]] of remote objects by the collection of electromagnetic radiation. The first known [[practically]] functioning telescopes were [[invented]] in the Netherlands at the beginning of the 17th century. "Telescopes" can refer to a whole range of instruments operating in most regions of the [[electromagnetic]] [[spectrum]].
 
A '''telescope''' is an instrument [[designed]] for the [[observation]] of remote objects by the collection of electromagnetic radiation. The first known [[practically]] functioning telescopes were [[invented]] in the Netherlands at the beginning of the 17th century. "Telescopes" can refer to a whole range of instruments operating in most regions of the [[electromagnetic]] [[spectrum]].
  
The word "telescope" (from the [[Greek]] τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos "far-seeing") was coined in 1611 by the [[Greek]] [[mathematician]] [http://en.wikipedia.org/wiki/Giovanni_Demisiani Giovanni Demisiani] for one of [http://en.wikipedia.org/wiki/Galileo_Galilei Galileo Galilei]'s instruments presented at a banquet at the [http://en.wikipedia.org/wiki/Accademia_dei_Lincei Accademia dei Lincei]. In the Starry Messenger Galileo had used the term "perspicillum".
+
The word "telescope" (from the [[Greek]] τῆλε, tele "far" and σκοπεῖν, skopein "to look or see"; τηλεσκόπος, teleskopos "far-seeing") was coined in 1611 by the [[Greek]] [[mathematician]] [https://en.wikipedia.org/wiki/Giovanni_Demisiani Giovanni Demisiani] for one of [https://en.wikipedia.org/wiki/Galileo_Galilei Galileo Galilei]'s instruments presented at a banquet at the [https://en.wikipedia.org/wiki/Accademia_dei_Lincei Accademia dei Lincei]. In the Starry Messenger Galileo had used the term "perspicillum".
 
==History==
 
==History==
The earliest [[evidence]] of working telescopes were the [http://en.wikipedia.org/wiki/Refracting_telescope refracting telescopes] that appeared in the Netherlands in 1608. Their [[development]] is credited to three [[individuals]]: [http://en.wikipedia.org/wiki/Hans_Lippershey Hans Lippershey] and [http://en.wikipedia.org/wiki/Zacharias_Janssen Zacharias Janssen], who were spectacle makers in Middelburg, and [http://en.wikipedia.org/wiki/Jacob_Metius Jacob Metius] of Alkmaar. Galileo greatly improved upon these [[designs]] the following year.
+
The earliest [[evidence]] of working telescopes were the [https://en.wikipedia.org/wiki/Refracting_telescope refracting telescopes] that appeared in the Netherlands in 1608. Their [[development]] is credited to three [[individuals]]: [https://en.wikipedia.org/wiki/Hans_Lippershey Hans Lippershey] and [https://en.wikipedia.org/wiki/Zacharias_Janssen Zacharias Janssen], who were spectacle makers in Middelburg, and [https://en.wikipedia.org/wiki/Jacob_Metius Jacob Metius] of Alkmaar. Galileo greatly improved upon these [[designs]] the following year.
  
The [[idea]] that a [[mirror]] could be used as an objective instead of a [[lens]] was being [[investigated]] soon after the [[invention]] of the [http://en.wikipedia.org/wiki/Refracting_telescope refracting telescope]. The [[potential]] advantages of using [http://en.wikipedia.org/wiki/Parabolic_reflector parabolic mirrors], primarily reduction of [http://en.wikipedia.org/wiki/Spherical_aberration spherical aberration] with no [http://en.wikipedia.org/wiki/Chromatic_aberration chromatic aberration], led to many proposed [[designs]] and several attempts to build [http://en.wikipedia.org/wiki/Reflecting_telescope reflecting telescopes]. In 1668, [http://en.wikipedia.org/wiki/Isaac_Newton Isaac Newton] built the first [[practical]] reflecting telescope, which bears his name, the [http://en.wikipedia.org/wiki/Newtonian_telescope Newtonian reflector].
+
The [[idea]] that a [[mirror]] could be used as an objective instead of a [[lens]] was being [[investigated]] soon after the [[invention]] of the [https://en.wikipedia.org/wiki/Refracting_telescope refracting telescope]. The [[potential]] advantages of using [https://en.wikipedia.org/wiki/Parabolic_reflector parabolic mirrors], primarily reduction of [https://en.wikipedia.org/wiki/Spherical_aberration spherical aberration] with no [https://en.wikipedia.org/wiki/Chromatic_aberration chromatic aberration], led to many proposed [[designs]] and several attempts to build [https://en.wikipedia.org/wiki/Reflecting_telescope reflecting telescopes]. In 1668, [https://en.wikipedia.org/wiki/Isaac_Newton Isaac Newton] built the first [[practical]] reflecting telescope, which bears his name, the [https://en.wikipedia.org/wiki/Newtonian_telescope Newtonian reflector].
  
The [[invention]] of the [http://en.wikipedia.org/wiki/Achromatic_lens achromatic lens] in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes. [http://en.wikipedia.org/wiki/Reflecting_telescope Reflecting telescopes], though not [[limited]] by the [[color]] [[problems]] seen in refractors, were hampered by the use of fast tarnishing [http://en.wikipedia.org/wiki/Speculum_metal speculum metal] [[mirrors]] employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857,[7] 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 [[research]]ing 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).
+
The [[invention]] of the [https://en.wikipedia.org/wiki/Achromatic_lens achromatic lens] in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes. [https://en.wikipedia.org/wiki/Reflecting_telescope Reflecting telescopes], though not [[limited]] by the [[color]] [[problems]] seen in refractors, were hampered by the use of fast tarnishing [https://en.wikipedia.org/wiki/Speculum_metal speculum metal] [[mirrors]] employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857,[7] 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 [[research]]ing 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).
  
The 20th century also saw the [[development]] of telescopes that worked in a wide range of wavelengths from [http://en.wikipedia.org/wiki/Radio_telescope radio] to [http://en.wikipedia.org/wiki/Gamma-ray_telescope gamma-rays]. The first [[purpose]] built radio telescope went into operation in 1937. Since then, a tremendous variety of [[complex]] astronomical instruments have been [[developed]].[http://en.wikipedia.org/wiki/Telescope]
+
The 20th century also saw the [[development]] of telescopes that worked in a wide range of wavelengths from [https://en.wikipedia.org/wiki/Radio_telescope radio] to [https://en.wikipedia.org/wiki/Gamma-ray_telescope gamma-rays]. The first [[purpose]] built radio telescope went into operation in 1937. Since then, a tremendous variety of [[complex]] astronomical instruments have been [[developed]].[https://en.wikipedia.org/wiki/Telescope]
 
==External links==
 
==External links==
* [http://galileo.rice.edu/sci/instruments/telescope.html ''The Galileo Project - The Telescope'' by Al Van Helden '']
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* [https://galileo.rice.edu/sci/instruments/telescope.html ''The Galileo Project - The Telescope'' by Al Van Helden '']
* [http://www.aip.org/history/cosmology/tools/tools-first-telescopes.htm "The First Telescopes". Part of an exhibit from Cosmic Journey: A History of Scientific Cosmology] by the American Institute of Physics
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* [https://www.aip.org/history/cosmology/tools/tools-first-telescopes.htm "The First Telescopes". Part of an exhibit from Cosmic Journey: A History of Scientific Cosmology] by the American Institute of Physics
* [http://www.timeline-help.com/telescope-timeline.html Timeline of telescopic technology]
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* [https://www.timeline-help.com/telescope-timeline.html Timeline of telescopic technology]
  
 
[[Category: Astronomy]]
 
[[Category: Astronomy]]

Latest revision as of 01:50, 13 December 2020

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Etymology

New Latin telescopium, from Greek tēleskopos farseeing, from tēle- tele- + skopos watcher; akin to Greek skopein to look

Definitions

Description

A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century. "Telescopes" can refer to a whole range of instruments operating in most regions of the electromagnetic spectrum.

The word "telescope" (from the 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

The earliest evidence of working telescopes were the refracting telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals: Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, and Jacob Metius of Alkmaar. Galileo greatly improved upon these designs the following year.

The idea that a mirror could be used as an objective instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using parabolic mirrors, primarily reduction of spherical aberration with 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, which 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,[7] 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).

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 tremendous variety of complex astronomical instruments have been developed.[1]

External links