$who invented refracting telescope$ $who invented refracting telescope$

In 1684 he used one of his aerial telescopes to find Dione and Tethys, two satellites of Saturn. On this tower he mounted long tubed telescopes and the objectives of aerial telescopes made for him by the Italian optician Giuseppe Campani. Applications Īn engraving of The Paris Observatory in the beginning of the 18th century with the wooden 'Marly Tower' on the right.Īstronomer Giovanni Domenico Cassini had the wooden Marly Tower, originally built as part of the Machine de Marly to lift water for the reservoirs and fountains at the Gardens of Versailles, moved to the grounds of the Paris Observatory. Adrien Auzout and others made telescopes of from 300 to 600 ft (90 to 180 m) focal length, and Auzout proposed a huge aerial telescope 1,000 ft in length that he would use 'to observe animals on the Moon'. presented a 7.5 inch (190 mm) diameter 123 ft (37.5 m) focal length objective to the Royal Society of London in 1690. Christiaan Huygens states that in 1686 he and his brother made objectives of 8 inch (200 mm) and 8.5 inch (220 mm) diameter and 170 and 210 ft (52 and 64 m) focal length, respectively. The objectives for aerial telescopes sometimes had very long focal lengths. Other contrivances for the same purpose are described by Philippe de la Hire and by Nicolaas Hartsoeker. Fainter objects could be found by looking for the reflection of a lamp held in the observer's hand being bounced back by the objective and then centering that reflection on the object. The telescope could be aimed at bright objects such as planets by looking for their image cast on a white pasteboard ring or oiled translucent paper screen and then centering them in the eyepiece. The Huygenses contrived some ingenious arrangements for aiming these 'aerial telescopes' at an object visible in the night sky. Christiaan Huygens published designs for these tubeless 'aerial telescopes' in his 1684 book Astroscopia Compendiaria, and their invention has been attributed to him and his brother Constantijn, although similar designs were also used by Adrien Auzout the idea is even sometimes attributed to Christopher Wren. The eyepiece was mounted in another short tube (sometimes on a stand), and the two tubes were kept aligned by a taut connecting string. In the Huygens' 'aerial' telescope the objective was mounted inside a short iron tube mounted on a swiveling ball-joint on top of an adjustable mast. Tubeless 'aerial' telescopes Īround 1675 the brothers Christiaan and Constantijn Huygens decided to accommodate the very long focal length objectives they were creating by eliminating the tube altogether.

$who invented refracting telescope$

Their value as research tools was minimal since the telescope's support frame and tube flexed and vibrated in the slightest breeze and sometimes collapsed altogether. Besides having very long tubes, these telescopes needed scaffolding or long masts and cranes to hold them up. As the objective diameter of these refracting telescopes was increased to gather more light and resolve finer detail they began to have focal lengths as long as 150 feet.

$who invented refracting telescope$

They also realized that when they doubled the diameter of their objectives they had to make the objective's focal length 4 times as long (focal length had to be squared) to achieve the same amount of minimal chromatic aberration. Telescope makers from that era found that very long focal length objectives had no appreciable chromatic aberration (the uncorrected chromatic aberration fell within the large diffraction pattern at focus). This degraded the quality of the images they produced. Telescopes built in the 17th and early 18th century used single element non-achromatic objective lenses that suffered from interfering rainbow halos ( chromatic aberration) introduced by the non-uniform refractive properties of single glass lenses. 1673 engraved illustration of Johannes Hevelius's 8 inch telescope with an open work wood and wire 'tube' that had a focal length of 150 feet to limit chromatic aberration.

$who invented refracting telescope$

Who invented refracting telescope