Angelo Secchi was born on the 18th of
June, 1818 in Reggio,
Italy. At the age of 15, be joined the
Jesuit order. In 1844, Angelo began his
theological studies and was ordained a
priest three years later. His primary interest was the
natural sciences - especially
physics and
mathematics. He lectured at the
Collegio Romano in 1839 until 1848 when he left due to
political unrest in Italy that eventually led to the expulsion of the
Jesuits. At this point, he traveled to
England, and later to
Georgetown University, and then returning to
Europe. In 1852, he returned to
Rome, and founded a new observatory at the Collegio Romano where he remained until his death on 26
February 1878.
Of his contributions to astronomy, he is most well known for his work on stellar spectral classification based upon the strength of the hydrogen absorption line in the spectra. This was the first use of spectroscopy systematically used for classifying the types of stars. His classifications were the foundations upon which the modern system is based.
Angelo Secchi was also very interested in solar physics. His
studies included solar prominences which were visible during eclipses.
These studies provided the first demonstrations that prominences
are features of the sun. He also wrote a number of books on astronomy
ranging from technical treaties to astronomy for the general public to
astronomy for children.
As the father of modern astrophysics, he was the first to suggest
that the core of the sun was a gas with the temperature of the gas
decreasing steadily from the center to the surface. While his
theories on sunspots and prominences have been obsoleted, his
impact on science at the time was considerable.
He is also very well known for the Secchi disk which is used to
measure the clarity of water.