refracting telescope

refracting telescopea refracting telescope;f indicates the focus

re·fract·ing telescope

(rĭ-frăk′tĭng)n. A telescope in which light from an object is gathered and focused by a lens, with the resulting image magnified by the eyepiece.

refracting telescope

n (Astronomy) a type of telescope in which the image is formed by a set of lenses. Also called: refractor Compare reflecting telescope

tel•e•scope

(ˈtɛl əˌskoʊp)

n., adj., v. -scoped, -scop•ing. n. 1. an optical instrument for making distant objects appear larger and nearer when viewed directly through lenses (refracting telescope) or indirectly as through images focused by a concave mirror (reflecting telescope). adj. 2. consisting of parts that slide one within another. v.t. 3. to force together, one into another, in the manner of the sliding tubes of a jointed telescope. 4. to shorten or condense. v.i. 5. to slide together in the manner of the tubes of a telescope. 6. to be driven one into another, as railroad cars in a collision. 7. to become condensed. [1640–50; < New Latin telescopium or Italian telescopio]

re·fract·ing telescope

(rĭ-frăk′tĭng) A telescope in which light from an object is gathered and focused by lenses. See more at telescope.

Thesaurus

Noun

$refracting telescope - optical telescope that has a large convex lens that produces an image that is viewed through the eyepiece$ refracting telescope - optical telescope that has a large convex lens that produces an image that is viewed through the eyepiecefield glass, spyglass, glass - a small refracting telescopeGalilean telescope - a type of refracting telescope that is no longer used in astronomyoptical telescope - an astronomical telescope designed to collect and record light from cosmic sources

Translations

refracting telescope

a type of telescope in which the image is formed by a set of lenses

refracting telescope

(ri-frakt -ing) (refractor) A telescope employing an objective lens to bring the light rays to a focus. The first telescopes were simple refractors with single-lens objectives: these were the Galilean and Keplerian telescopes, introduced in the early 17th century. They were supplanted by reflecting telescopes in the last quarter of that century because no-one at that time could overcome their chromatic aberrations, which introduced brilliant false color effects in the images. Although John Dollond discovered how to make an achromatic lens in 1756, he could make only small diameters suitable for terrestrial telescopes; glass makers did not know how to make large uniform disks of crown and flint glass. This obstacle was overcome in the early 1800s by Joseph Fraunhofer, who made the 24-cm refractor at Dorpat and the 16-cm heliometer at Königsberg. His successor, Georg Merz, supplied the 32.4-cm equatorial refractor to the Royal Greenwich Observatory and manufactured the 38-cm refractor that was the first large telescope to be mounted in the USA, at Cambridge, Massachusetts, in 1847.

For years after this, American astronomers leaned strongly toward the refractor. By the 1880s Alvan Clark was making relatively large refractors: a 47-cm diameter instrument for the Dearborn Observatory, a 91-cm one for Lick Observatory, and a 102-cm one for Yerkes Observatory. Other very large refractors built in the late 19th century are the 61-cm at both Lowell Observatory, Arizona, and the Pic du Midi in France, the 75-cm at Pulkovo Observatory, St Petersburg, and the 83-cm at the Meudon Observatory in Paris. There are great technical problems in making large lenses free of imperfections and impurities, and of supporting these lenses (only around the edge) so that distortion of the image is minimal. The desire for ever larger apertures to reach ever farther and fainter objects in space has meant that the major telescopes built in the 20th and 21st centuries have been reflectors.

The surviving large refracting telescopes are mainly used in astrometry for the measurement of stellar positions, proper motions, and parallax. Refractors are often preferred by visual observers because of their long focal length and closed tube; the latter avoids air currents in the tube, which often cause an unsteady image.

refracting telescope

[ri′frak·tiŋ ′tel·ə‚skōp] (optics) A telescope in which a lens gathers light and forms a real image of an object. Also known as refractor telescope.

refracting telescope

re·fract·ing telescope

refracting telescope

tel•e•scope

re·fract·ing telescope

refracting telescope

refracting telescope

refracting telescope

refracting telescope

refracting telescope

Words related to refracting telescope

noun optical telescope that has a large convex lens that produces an image that is viewed through the eyepiece

Related Words