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Optical telescope

Instrument that gathers visible light to magnify distant objects.

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Optical telescope

NASA Goddard Space Flight Center from Greenbelt, MD, USA · Public domain

Its light-gathering power is considered its most important feature, acting like a bucket that collects photons to brighten the image.[1] An optical telescope's ability to gather light is described as its capacity to collect significantly more photons than the human eye can.[1]

Quick Facts

Field
Optics, Astronomy
Known for
Gathering and focusing visible light to create magnified images of distant objects
Types
  • Refracting
  • Reflecting
  • Catadioptric

Facts from the source article.

Key facts and history

The telescope was not the invention of scientists but rather the product of optical craftsmen.[2] The first documented refracting optical telescope appeared in the Netherlands in 1608, with a patent filed by spectacle maker Hans Lippershey.[3] The achromatic lens, which corrected chromatic aberration, was first designed by Chester Moor Hall in 1729.[4] Isaac Newton is generally credited with constructing the first practical reflecting telescope in 1668.[5]

The electronics revolution of the early 21st century led to computer-connected telescopes that allow non-professional skywatchers to observe using digital astrophotographic techniques.[6] After learning about the telescope's invention, Galileo Galilei created his own enhanced versions within twelve months and became the initial person to release astronomical findings obtained with a telescope.[7] A telescope design employing a convex eyepiece, frequently referred to as the Keplerian telescope, was suggested by Johannes Kepler as an enhancement.[8]

What the cited sources add

The Ryukyu Astronomy Club notes that all parameters derived from optical formulae are purely theoretical and can never be reached in practice.[9] The same source provides a formula for light-gathering power as the aperture divided by 7 mm, squared, compared to the human eye.[9] The Galileo Project account states that by about 1450 the ingredients for making a telescope were already present.[2] A Scientific American article describes the eVscope, a 4.5-inch Newtonian reflector that uses sensors and software to amplify light from faint targets.[10]

This eVscope can image objects as faint as apparent magnitude 15, according to the same article.[10] The Galileo Project notes that the States General in The Hague discussed patent applications for the telescope in October 1608.[2]

References

  1. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: "Telescope Formulae", SaharaSky Observatory, 3 July 2012; "Optical Formulae", Ryukyu Astronomy Club, 2 January 2012 (we also read that source) en.wikipedia.org
  2. galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden. facts only, no text reused. galileo.rice.edu
  3. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: galileo.rice.edu The Galileo Project > Science > The Telescope by Al Van Helden – "the telescope was not the invention of scientists; rather, it was the product; Fred Watson, "Ian Stargazer: The Life and Times of the Telescope", Allen & Unwin, 2007, p. 55; Henry C. King, "The History of the Telescope", Courier Corporation, 2003, p. 25–29; progression is followed through Robert Grosseteste Witelo, Roger Bacon, through Johannes Kepler, D. C. Lindberg, Theories of Vision from al-Kindi to Kepler, (Ch; Fred Watson, "Ian Stargazer: The Life en.wikipedia.org
  4. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: King, "The invention and early development of the achromatic telescope", Popular Astronomy, 1948, p. 75 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: A. Rupert Hall, "Isaac Newton: Adventurer in Thought", Cambridge University Press, 1996, p. 67 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: "Les télescopes connectés débarquent. Episode 2/2 : l'eVscope", Ciel & espace, November 2018; Billings, "New Telescope 'Gives Back the Sky' to City-Dwellers", Scientific American, 13 September 2018 (we also read that source) en.wikipedia.org
  7. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: Albert Van Helden, Sven Dupré, Rob van Gent, The Origins of the Telescope, Amsterdam University Press, 2010, page 183 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Optical telescope" (CC BY-SA 4.0), which cites: See his books Astronomiae Pars Optica and Dioptrice (original not read by us) en.wikipedia.org
  9. "Optical Formulae", Ryukyu Astronomy Club, 2 January 2012. facts only, no text reused. nexstarsite.com
  10. Billings, "New Telescope 'Gives Back the Sky' to City-Dwellers", Scientific American, 13 September 2018. facts only, no text reused. blogs.scientificamerican.com

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Optical telescope (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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