Angelo Secchi (1818–1878)
Angelo Secchi wasborn on 18 June 1818 in Reggio, Italy. He joined the Jesuit at age 15,began his theological studies in 1844, and was ordained priest in1847. In 1839 he beganlecturing on physics and mathematics at the Jesuits'Collegio Romano. In 1848, due to the political unrest in Italy that led tothe general expulsion of the Jesuit order, he traveled to England, thento Georgetown University, near Washington, where he taught the naturalsciences. He was back in Europe within a year, and in 1852 returned to Rome,founding a new observatory at the Collegio Romano. He remainedbased in Rome until his death, on 26 February 1878.
Secchi made many important contributions to the astronomy ofhis days, in particular on stellar spectral classification. He was the firstto make systematic use of spectroscopy in stellar classification. Hisfour class scheme prevailed throughout much of the secondhalf of the nineteenth century, and paved the way for all laterclassification schemes.Secchi was also extremely active insolar physics, an area he became interested in during his stay inAmerica. He studied prominences during eclipses, both visuallyand spectroscopically, and provided the first demonstrations that prominencesare features belonging to the Sun. He wrote a number of astronomicalbooks in Italian, some quite technical, others aimed at the general public,and one for children.His influential solar monograph Le Soleilwas first published in Paris in 1870, with a German translation appearing in18XX and the second French edition in 1875.
Secchi was the first astrophysicist to suggest that the solar core is ina gaseous state, with the temperature steadily decreasing from thecenter to the surface. Some of his theories onsunspots, granulation and prominences wouldtoday be considered obsolete, but their influence on nineteenthcentury astronomy and solar physics was considerable. He was elected to England's Royal Society and Royal AstronomicalSociety, of the French Académie des Sciences, and of Russia's ImperialAcademy of St. Petersburg. In Italy he presided for many years over theAccademia dei Nuovi Lincei, and founded the Societa degli SpettroscopistiItaliani, devoted to spectroscopic studies of the Sun.