įor reflecting telescopes, which use a curved mirror in place of the objective lens, theory preceded practice. The next big step in the development of refractors was the advent of the Achromatic lens in the early 18th century, which corrected the chromatic aberration in Keplerian telescopes up to that time-allowing for much shorter instruments with much larger objectives. Johannes Kepler proposed an improvement on the design that used a convex eyepiece, often called the Keplerian Telescope. Galileo's telescope used a convex objective lens and a concave eye lens, a design is now called a Galilean telescope. Word of the invention spread fast and Galileo Galilei, on hearing of the device, was making his own improved designs within a year and was the first to publish astronomical results using a telescope. It is in the Netherlands in 1608 where the first documents describing a refracting optical telescope surfaced in the form of a patent filed by spectacle maker Hans Lippershey, followed a few weeks later by claims by Jacob Metius, and a third unknown applicant, that they also knew of this "art". But the most significant step cited in the invention of the telescope was the development of lens manufacture for spectacles, first in Venice and Florence in the thirteenth century, and later in the spectacle making centers in both the Netherlands and Germany. The lens and the properties of refracting and reflecting light had been known since antiquity, and theory on how they worked was developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the telescope's invention in early modern Europe. The telescope is more a discovery of optical craftsmen than an invention of a scientist. People use optical telescopes (including monoculars and binoculars) for outdoor activities such as observational astronomy, ornithology, pilotage, hunting and reconnaissance, as well as indoor/semi-outdoor activities such as watching performance arts and spectator sports.įurther information: History of the telescope The larger the objective, the more light the telescope collects and the finer detail it resolves. Catadioptric telescopes, which combine lenses and mirrorsĪn optical telescope's ability to resolve small details is directly related to the diameter (or aperture) of its objective (the primary lens or mirror that collects and focuses the light), and its light-gathering power is related to the area of the objective.Reflecting telescopes, which use mirrors ( catoptrics).Refracting telescopes, which use lenses and less commonly also prisms ( dioptrics).
There are three primary types of optical telescope: The Large Binocular Telescope at the Mount Graham International Observatory in Arizona uses two curved mirrors to gather lightĪn optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors.
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