![]() Where λ is the wavelength of radiation being detected and D is the limiting aperture of the telescope, usually the diameter of the objective, or primary optic. The angular resolution limit, q, of a telescope operating under ideal conditions is given by the simple formula: The resolution, or resolving power, of a telescope is defined as being the minimum angular separation between two different objects that can be detected. The more light a telescope can gather, the more distant the objects it can detect, and therefore larger telescopes increase the size of the observable universe. The light gathering power grows as the area of the objective increases, or the square of its diameter if it is circular. Palomar, California, for instance can gather 25 times more light than the 40 in (102 cm) Yerkes telescope at Williams Bay, Wisconsin, the largest refracting telescope in the world. The 200 in (508 cm) diameter reflecting telescope at Mt. The reason for this occurrence is that larger telescopes can see further because they can collect more light. However, there are many telescopes around the world with diameters several times this value. As will be seen below, resolution limits on telescopes would not call for an aperture much larger than about 30 in (76 cm). The primary function of a telescope is that of radiation gathering, in many cases light gathering. Computers are now used to aid in the design of large, complex telescope systems. Since then, telescopes have increased in size and improved in image quality. With this telescope and several following versions, Galileo made the first telescopic observations of the sky and discovered lunar mountains, four of Jupiter ’s moons, sunspots, and the starry nature of the Milky Way galaxy. The following year, Italian astronomer and physicist Galileo Galilei (1564 – 1642) built the first astronomical telescope, from a tube containing two lenses of different focal lengths aligned on a single axis (the elements of this telescope are still on display in Florence, Italy). The first optical telescope was probably constructed by German-born Dutch lensmaker Hans Lippershey (1570 –1619), in 1608. The word telescope is derived from the Greek tele meaning far, and skopein meaning to view. The one characteristic all telescopes have in common is the ability to make distant objects appear to be closer. In a broader sense, telescopes can operateĪt most frequencies of the electromagnetic spectrum, from radio waves to gamma rays. The most common type is the optical telescope, a collection of lenses and/or mirrors that is used to allow the viewer to see distant objects more clearly by magnifying them or to increase the effective brightness of a faint object. ![]() Ref: /abs/1307.The telescope is an instrument that collects and analyzes the radiation emitted by distant sources. Zik and Hon’s work show that Galileo is clearly one of them. There are certainly many individuals in history who have made great strides beyond the state-of-the-art of the time. However, it’s not beyond belief that he stood head and shoulders above his peers in this respect, as in many others. But we’ll almost certainly never know what Galileo’s optical theory consisted of-he never published his ideas in this area. That’s an interesting conclusion that testifies to Galileo’s remarkable achievement. “We submit that Galileo had a novel optical theory which he did not want to divulge, but his practice and the extant instruments display it,” they say. “We think not.” Instead they argue that Galileo must have had had a much deeper understanding of optics. “Could these great achievements be accomplished by extending optics of the spectacle makers in a lightly theorized practice based on “systematized experience”?, they ask. Zik and Hon spend some time discussing these new features in the context of the optical technology of the time. ![]()
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