Telescope

The word "telescope" comes from two Greek roots: telo (τηλó) meaning “far” or “distant”, and skopein (σκοπειν) meaning “to see.” Together they simply mean “to see from far away.

A simple description of telescope is an instrument designed to magnify distant objects so that they can be viewed more easily. Telescopes historically have been constructed of lenses and mirrors which concentrate visible light into a smaller and more defined image. Template:TOC-right

Telescopes as research tool

Zik (2001) notes that before the telescope scientific observation relied on instruments such as Heron's diopter,, Levi Ben Gershom's cross-staff,, Egnatio Danti's torqvetto astronomico, Tycho's quadrant, Galileo's geometric military compass, and Kepler's ecliptic instrument. Galileo not only had to adapt the telescope to astronomy, he also had to create a system by which it could be integrated into scientific knowledge. To do so Galileo showed its images were real and not caused by defects in lenses nor illusions in the eye of the observer. More important he had to adapt or invent measurement techniques and provide a way to process data while recognizing the issue of measurement error. He realized that the accurate measurement of natural phenomena is a challenge and that suitable protocols had to be established and agreed to by the community of astronomers. Historians of science explore the linkage established by Galileo among theory, method, and instrument, in his case the telescope. Although the telescope was invented independently of astronomical science, Galileo's innovative optics married the machinery and the theory to close the gap between image in the eyepiece and scientific language--that is, between drawing what was seen and reporting physical facts. He thus bridged the gap between merely sketching the sky and actually describing it and created a scientific methodology using the new instrument that all astronomers came to follow..

History of the development of the telescope

Claims regarding Leonard Digges

Leonard Digges (?1515-?1559)was an English mathematician and architect who was the first in England to describe the altazimuth theodolitede. On the basis of much later comments by his son, some writers have claimed Digges might have devised a reflecting telescope. Apart from a brief few sentences by his son there is no independent evidence that he invented a working telescope for astronomical observation; it seems likely that he did indeed use a rather unwieldy lens–mirror combination for terrestrial viewing. His son Thomas, who was active in astronomy never claims to have used his father's supposed telescope; no one else claims to have seen it.

Thomas in 1571 recalled how his father had observed things with "Perspective glasses" on numerous occasions from a considerable distance and with witnesses present: The father "sundrie Times hath by proportionall Glasses duly situate in convenient angles, not onely discovered things farre off, read letters, numbered peeces of money with the very coyne and superscription thereof, cast by some of his freends of purpose uppon Downes in open fields, but also at seven miles declared what had been doon at that instant in private places."

Colin Ronan and Gilbert Satterthwaite built a working telescope in 2002 from a description found in a report on military and naval inventions, written in 1578 by William Bourne. It comprised a convex lens at the front and a curved mirror at the back, and gave an inverted image magnified 11x. There is no evidence that Bourne himself ever built the proposed telescope.

Hans Lipperhey

Lipperhey (or Lippershey) was a Dutch spectacle maker who filed a patent for the refractive telescope in 1608. At that time there were several other patents pending. Lepperhey was apparently employed to make two lenses, one convex and the other concave. When the client appeared to take possession of the lens he positioned them to show how they magnified distant objects when used in tandem. Another claimant to the patent was the son of Sacharias Janssen. Janssen later noted that his father already had a telescope of Italian manufacture, dated 1590. These events predate Lipperhey’s claims.

Galileo Galilei

Galileo's ink renderings of the moon: the first telescopic observations of a celestial object.

Galileo first heard of the telescope in 1609 and was able construct his own model from the description given him about the device patented by a spectacle maker in the Netherlands, Hans Lipperhey. He made several models including an 8-power telescope and a 20-power. Galileo went on to make observations of the Moon, the Sun, the planets and stars

See also

• Isaac Newton

Further reading

for a more detailed guide see the Bibliography subpage

• Brunier, Serge, and Anne-Marie Lagrange. Great Observatories of the World (2005) 240pp; covers 56 observatories excerpt and text search
• King, Henry C. The History of the Telescope (2003) 480pp
• McCray, W. Patrick Giant Telescopes: Astronomical Ambition and the Promise of Technology (2nd ed. 2006) excerpt and text search
• Van Helden, A. "Telescope and Authority From Galileo to Cassini." Osiris 1994. Vol. 9:9-29 in JSTOR
• Zik, Yaakov. "Science and Instruments: the Telescope as a Scientific Instrument at the Beginning of the Seventeenth Century." Perspectives on Science 2001 9(3): 259-284. Issn: 1063-6145 Fulltext: Project Muse
• Zimmerman, Robert. "More Light!" American Heritage of Invention & Technology 2002 18(2): 14-23. Issn: 8756-7296, on 1970s Fulltext: online
• Zirker, J. B. An Acre of Glass: A History and Forecast of the Telescope Johns Hopkins U. Press, 2005. 343 pp. excerpt and text search