장 피카르: 두 판 사이의 차이

•The Galileo Project

 

 

피카르는 또한 천체의 [[적경]]을 측정하는 표준 방법도 개발하였다.<ref>Picard did not conceive the method of measuring a celestial body's right ascension by recording the time at which the body crossed the observer’s meridian. According to French astronomer Camille Guillaume Bigourdan (1851-1932), the French astronomers Adrien Auzout (1622-1691) and Jacques Buot (or Buhot) (<1623-1678), the Dutch physicist Christiaan Huygens (1629-1695), the Czech physician/astronomer Hagecius (1525-1600) had all suggested the method ; even the ancient Greek astronomer Hipparchus (190 B.C.E.-120 B.C.E.) had hinted at it. However, the method had never been put into practice because it required both a telescope in place of the traditional sight of a quadrant and a very accurate clock. Picard was the first astronomer to actually employ the method. [G. Bigourdan (1917) "Sur l'emplacement et les coordonées de l'Observatoire de la porte Montmartre" (On the site and coordinates of the observatory by the Montmartre gate), ''Comptes rendus'', vol. 164, pages 537-543.] In October 1669, Picard sent, to the Royal Academy of Sciences in Paris, a report of his celestial observations during the preceding year, which included the observation of two bright stars, Regulus and Arcturus, while the sun was still in the sky. The report was recorded in the ''Registres des Procès-verbaux de l‘Académie des Sciences.'' On reading the report, it becomes apparent that Picard had been using clocks to determine the right ascension of stars. French astronomer Pierre Charles Le Monnier (1715-1799) records an extract of Picard’s report and then remarks: ''"Cette Observation est remarquable, étant inoüi qu'on eût jamais pris la Hauteur Méridienne des Etoiles fixes non seulment en plein Soleil, mais pas même encore dans la force du Crépuscle ; desorte qu'il est maintenant facile (continue M. Picard) de trouver immédiatement les Ascensions droites des Etoiles fixes non seulment par les Horloges à Pendule, mais aussi par l'Observation du Vertical du Soleil au mème temps qu'on observera la hauteur Méridienne d'une Etoile fixe."'' (This observation is remarkable, it being unheard of that one has ever taken the meridian altitude of fixed stars not only in full sun, but still not in the force of twilight; so it is now easy (continues Mr. Picard) to find immediately the right ascensions of the fixed stars not only by pendulum clocks but also by observation of the vertical of the sun at the same time that one observes the meridian altitude of a fixed star.) [Pierre-Charles Le Monnier, ''Histoire céleste, ou Recueil de toutes les observations astronomiques faites par ordre du Roi'' … (Paris, France: Briasson, 1741), page 40.]</ref><ref>Wolf, Abraham, ''A History of Science, Technology, and Philosophy in the 16th and 17th Centuries,'' vol. 2 (London, England: George Allen and Unwin, 1950), page 172.</ref> 이 방법에서 관찰자는 천체가 관찰자의 자오선을 통과하는 시간을 기록한다. 피카르는 네덜란드의 물리학자 크리스티안 하위헌스가 당시 개발한 정밀 진자 시계를 이용해 관찰하였다.