Secchi , Pietro Angelo
(1818–1878) Italian astronomer
Secchi, who was born at Reggio in Italy, was a Jesuit who lectured in physics and mathematics. He spent some time abroad when the Jesuits were expelled from Rome, being at one time professor of physics at Georgetown University, Washington. He returned to Italy in 1849, becoming professor of astronomy and director of the observatory of the Roman College, which he rebuilt and reequipped.
He researched in stellar spectroscopy and his main work was done on spectral types. He introduced some order into the mass of new observations that was pouring in from the early spectroscopists. In 1867 he proposed four spectral classes. Class 1 had a strong hydrogen line and included blue and white stars; class 2 had numerous lines and included yellow stars; class 3 had bands rather than lines, which were sharp toward the red and fuzzy toward the violet and included both orange and red lines; finally, class 4 had bands that were sharp toward the violet and fuzzy toward the red and included red lines alone. These spectral types mark an important, and fairly straightforward, temperature sequence. Secchi's classification, as very much extended and modified by Edward Pickering and Annie Cannon, has become one of the basic tools of astrophysicists.

Scientists. . 2011.

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  • Secchi, Pietro Angelo — ▪ Italian astronomer born June 29, 1818, Reggio nell Emilia, duchy of Modena [now in Italy] died Feb. 26, 1878, Rome, Italy       Italian Jesuit priest and astrophysicist, who made the first survey of the spectra of stars (star) and suggested… …   Universalium

  • Secchi — Pietro Angelo …   Scientists

  • Angelo Secchi — Pietro Angelo Secchi (* 29. Juni 1818 in Reggio nell’Emilia, Italien; † 26. Februar 1878 in Rom) war ein italienischer Astronom und Jesuitenpater. Secchi schloss sich bereits im Alter von 15 Jahren dem Jesuitenorden an und wurde mit 17 Student am …   Deutsch Wikipedia

  • Angelo Secchi — Naissance 18 juin 1818 Reggio Emilia (Italie) Décès 26 février 1878 (à 59 ans) …   Wikipédia en Français

  • Angelo Secchi — Nacimiento 29 de junio de 1818 Reggio Emilia, Italia Fallecimiento …   Wikipedia Español

  • Secchi —   [ sekki], Pietro Angelo, italienischer Physiker, * Reggio nell Emilia 29. 6. 1818, ✝ Rom 26. 2. 1878; musste als Jesuit 1848 Italien verlassen, wirkte in Stonyhurst (County Lancashire, England) und Georgetown bei Washington (D. C.), 1849… …   Universal-Lexikon

  • Angelo Secchi — Infobox Scientist name = Angelo Secchi box width = image width =150px caption = Angelo Secchi birth date = 29 June 1818 birth place = Reggio Emilia death date = 26 February 1878 death place = residence = Rome citizenship = nationality = Italian… …   Wikipedia

  • Secchi disk — The Secchi disk, created in 1865 by Pietro Angelo Secchi, is a circular disk used to measure water transparency in oceans and lakes. The disc is mounted on a pole or line, and lowered slowly down in the water. The depth at which the pattern on… …   Wikipedia

  • Secchi disc — /ˈsɛki dɪsk/ (say sekee disk) noun a disc used to gauge water clarity by measuring the depth at which it is no longer visible from the surface. {created in 1865 by Pietro Angelo Secchi, Italian astronomer, 1818–78} …   Australian English dictionary

  • Secchi — /sek ee/; It. /sek kee/, n. Pietro Angelo /pye trddaw ahn je law/, 1818 78, Italian Jesuit and astronomer. * * * …   Universalium

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