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23-06-2017, 11:02 AM

Sir need a investigatory project on the study of telescope
Please help me
It's urgent

jaseela123d · 29-06-2017, 11:27 AM

A telescope is an optical instrument that helps the observation of remote objects by collecting electromagnetic radiation (such as visible light). The first known practical telescopes were invented in the Netherlands in the early 17th century, using glass lenses. They found use in both terrestrial and astronomy applications.

In a few decades, the reflecting telescope was invented, which used mirrors to collect and focus 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 was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of the instruments of Galileo Galilei presented at a banquet at the Accademia dei Lincei. In the Starlord, Galileo had used the term perspicillum.

The first working telescopes recorded were the refracting telescopes that appeared in Holland in 1608. Its development is attributed to three individuals: Hans Lippershey and Zacharias Janssen, who were show manufacturers in Middelburg, and Jacob Metius of Alkmaar. Galileo heard of the Dutch telescope in June 1609, built his own within a month and improved the design of the following year. Also in 1609, Thomas Harriot became the first person known to point a telescope to the sky to make telescopic observations of a celestial object.

The idea that the lens, or light gathering element, could be a mirror instead of a lens was being investigated shortly after the invention of the refracting telescope. The potential advantages of the use of parabolic mirrors - reduction of spherical aberration and absence of chromatic aberration - led to many proposed designs and several attempts to construct reflecting telescopes. In 1668, Isaac Newton constructed the first practical reflecting telescope, of a design that now bears his name, the Newtonian reflector.

The invention of the achromatic lens in 1733 partially corrected chromatic aberrations present in the single lens and allowed the construction of more functional and shorter refractive telescopes. Reflecting telescopes, although not limited by the color problems observed in refractors, were hampered by the use of fast-mirrored metal mirrors that became fogged during the eighteenth and early nineteenth century - a problem attenuated by the introduction Of silver-coated glass mirrors in 1857, Mirrors in 1932. The maximum physical size limit for refraction of telescopes is approximately 1 meter (40 inches), saying that the vast majority of large optical telescopes research built since change Of 20th century have been reflective. The largest reflecting telescopes currently have lenses greater than 10 m (33 ft), and work is underway in several 30-40 m designs.

The 20th century also saw the development of telescopes that worked on a wide range of wavelengths from radio to gamma rays. The first purpose-built radio telescope came into operation in 1937. Since then, a tremendous variety of complex astronomical instruments has developed.

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