Telescope

The word "telescope" comes from two Greek words: tele (τηλε) 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.

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History of the development of the telescope

Leonard Digges (1520-1559)

Leonard Digges was a writer of mathematics and science in English, one of the first people to popularise work in either field. He was also a surveyor who invented the theodolite, the telescope, the reflecting telescope and possibly the refractive telescope. He published a number of works during his lifetime but his achievements were expanded and revised by his son Thomas and published after Leonard's death, some of the work for the first time. Historically, it is difficult to separate the works of Leonard and Thomas. Additionally, there is no evidence that Leonard actually used a telescope but there is clear evidence that he and his son Thomas did understand the design and function of telescopes. For this reason, Hans Lipperhey is credited by many authorities with having invented the telescope.

Thomas Digges (1543-1595)

In 1571, Thomas Digges published Leonard Digges's book on the telescope, Pantometria, twelve years after his father's death. Panometria was the first publications to discuss the invention of the telescope in English. Thomas had extended, revised and enhanced the book and he wrote the preface. J J O'Connor and E F Robertson note that while the description of how lenses could be combined to construct a telescope, there is no known evidence that the Diggeses did actually make a telescope and use one. Some authorities take exception to this view and regard the issue to be resolved. How is that the Diggeses knew how to construct a telescope and yet did not? Having constructed a telescope how is it they would not have used it? In his preface to the Pantometria, Thomas notes clearly how his father had observed things on numerous occasions from a considerable distance and with witnesses present. Clearly he was describing a telescope that had indeed been constructed and used.

The absence of specific notes on the use of a telescope are therefore not to be regarded as proof that the Diggeses, father and son, never made nor used a telescope.

Thomas’s publication, Alae seu scalae mathematicae, in 1573, was a Latin text prompted by the new star of 1572, a supernova. Thomas's observations were employed by Tycho Brahe in his work. The supernova created quite a stir worldwide and certainly in Europe. There was a tremendous increase in astronomical and astrological work and publications. Tycho Brahe's supernova was significant because it encouraged astronomers in the 16th-century to question their perception that the heavans were immutable, that is, unchanging. Thomas's contribution was to determined the nova's position and his conclusion that its appearance was a challenge to traditional cosmology of the day.

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