Astronomy Bio...Angelo Secchi

Jay Bitterman

Angelo (Pietro) Secchi was born on June 18, 1818 at Reggio in Emilia, Italy. On November 3, 1833 he entered the Jesuit Order at Rome and began his theological studies. After finishing his humanistic and philosophical studies in 1839 at the Roman College, his aptitude in the natural sciences led him to be appointed tutor of mathematics and physics at the Jesuits' Collegio Romano. In 1841 he became professor of physics in the Jesuit college at Loreto. On September 12, 1847, he was ordained a priest.

Due to the political unrest in Italy that led to the expulsion of the Jesuit order in 1848, he went to England and then to Georgetown University, near Washington DC, to teach natural science. In 1849 he was appointed director of Gregorian University in Rome and in 1852 founded a new observatory at the Collegio Romano. Secchi was particularly attracted to astrophysics, a challenging choice at a time when this field was hardly developed. In the years 1852 to 1853 he observed double stars, nebulae and planets and discovered three comets. Secchi revised the catalogue of double stars made by W. Struve at Dorpat. In 1859, after years of strenuous labor he published the chief portion of his results in the "Memorie Del Collegio Romano" that listed 10,000 verified double stars, to be continued in two supplements by his assistant in 1868 and 1875.

By 1852 the moon became the subject of Secchi's investigations. He made so perfect a map of the moon's great crater Copernicus that the Royal Society of London had reproduced many photographic copies and distributed them among those interested in astronomy. With the discovery of spectrum analysis by Kirchhoff and Bunsen in 1860, Secchi was the first to closely investigate the spectra of Uranus and Neptune.

He wrote numerous astronomical books in Italian. Some were quite technical, others directed towards the general public, and one was for children. In 1870 his influential solar monograph "Le Soleil" was first published in Paris and a German translation appeared in 1873 and a second French edition in 1875.

Secchi was the first astrophysicist to propose that the core of the sun is in a gaseous state and the temperature decreases from the center to the surface. Additionally he studied stellar spectroscopy, conducted the first systematic spectroscopic survey of the heavens, pioneered the classifying of stars by spectral type, studied sunspots, solar prominences, photographed solar corona during the eclipse in 1860, invented the heliospectroscope, star spectroscope, telespectroscope and meteorograph. He also published about 730 small papers for various scientific journals. While there are many spectral differences among individual stars, Secchi also found many similarities. Therefore, using these as a criterion, he identified four classes of spectra. With this discovery he is considered the father of the spectral classification of stars, a very powerful tool for research on the origins and structure of stellar systems.

After a debilitating illness, Angelo Secchi died on February 26, 1878. His successor was removed from the Observatory in 1879. Thus last of the papal observatories, which had weathered so many difficult times without receiving the recognition it deserved, came to an end. Its name was changed to Regio Osservatorio al Collegio Romano (Royal Observatory at the Roman College). In 1923 even this last bit was terminated.