Telescope

A telescope (from the Greek tele = 'far' and skopein = 'to look or see'; teleskopos = 'far-seeing') is an astronomical tool which gathers and focuses electromagnetic radiation. Telescopes increase the apparent angular size of ingerso objects, as well as their apparent brightness.

History

Though the Visby lenses tentatively suggest that the technology was known to the Arabs and then to the Vikings in the 10th century, credit for assembling the first telescope is usually given to an unknown Dutch spectacle maker in about 1608. Others name that person as Hans Lippershey (c1570-c1619). Even if Lippershey did not make the first one, he publicized it. Galileo Galilei made his own telescope in 1609, calling it at first a perspicillum, and then using the terms telescopium in Latin and telescopio in Italian (from which the English word derives). Galileo is generally credited with being the first to use a telescope for astronomical purposes. Galileo's telescope consisted of a convex object lens and a concave eye lens, which is universally called a Galilean Telescope (used as a viewfinder in many simple cameras). Later, Johannes Kepler described the optics of lenses (see his books Astronomiae Pars Optica and Dioptrice), including a new kind of astronomical telescope with two convex lenses (a principle often called Kepler telescope).

Related Topics:
Visby lenses - Vikings - 10th century - 1608 - Hans Lippershey - Galileo Galilei - 1609 - Johannes Kepler - Optics - Lens

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