The Reverend Father Angelo Secchi | |
|---|---|
 | |
| Church | Latin Church |
| Orders | |
| Ordination | 12 September 1847 |
| Rank | Priest |
| Personal details | |
| Born | (1818-06-28)28 June 1818 |
| Died | 26 February 1878(1878-02-26) (aged 59) |
| Nationality | Italian |
| Denomination | Catholicism |
| Scientific career | |
| Awards | Légion d'honneur, France |
| Fields | Astronomy |
| Institutions | Observatory of the Roman College |
Angelo SecchiS.J. (Italian pronunciation:[ˈandʒeloˈsekki]; 28 June 1818 – 26 February 1878) was anItalianCatholic priest andastronomer from theItalian region ofEmilia.[1] He was director of the observatory at thePontifical Gregorian University (then called theRoman College) for 28 years. He was a pioneer inastronomical spectroscopy, and was one of the first scientists to state authoritatively that theSun is astar.
Secchi was born inReggio Emilia, where he studied at the Jesuitgymnasium. At the age of 16, he entered theJesuit Order in Rome. He continued his studies at the Roman College, and demonstrated great scientific ability. In 1839, he was appointed tutor of mathematics andphysics at the college. In 1841, he became professor of physics at the Jesuit College inLoreto. In 1844, he begantheological studies in Rome, and wasordained a priest on 12 September 1847. In 1848, due to theRoman Revolution, the Jesuits were ordered to leave Rome. Secchi spent the next two years in theUnited Kingdom atStonyhurst College, where he metAlfred Weld, the Jesuit astronomer in charge of the Stonyhurst Observatory, who may have inspired him to take up the science. He moved on to theUnited States, where he taught for a time atGeorgetown University inWashington, D.C. He also took his doctoral examination in theology there.[2]
During his stay in America, he met CommanderMatthew Fontaine Maury, the first director of theUnited States Naval Observatory in Washington. He studied with Maury and corresponded with him for many years.[2]
He returned to Rome in 1850. On the recommendation of his late colleagueFrancesco de Vico, he became head of the observatory of the college at age 32. In 1853, under his direction, the crumbling observatory was relocated to a new facility on top of theSant'Ignazio Church (the chapel of the college).[3] Secchi served as director until his death.[4]
Secchi was elected to theAmerican Philosophical Society in 1860.[5]
His director position was challenged after 1870, when the remnant of thePapal States around Romewas taken over by theKingdom of Italy. In 1873, the college was declared property of the Italian government. When the government moved to take over the observatory as well, Secchi protested vigorously, and threatened to leave the observatory for one of several positions offered to him by foreign observatories. He was offered important scientific positions and political dignities by the government, but refused to pledge allegiance to the Kingdom in place of the Pope. The royal government did not dare to interfere with him, and he continued as director.[2]
He died in 1878 at age 59, in Rome.
Secchi made contributions to many areas of astronomy.
Secchi was especially interested in the Sun, which he observed continually throughout his career.
However, his main area of interest wasastronomical spectroscopy. He invented the heliospectrograph, star spectrograph, and telespectroscope. He showed that certainabsorption lines in thespectrum of the Sun were caused by absorption in the Earth'satmosphere.
Starting in 1863, he began collecting the spectra of stars, accumulating some 4,000 stellar spectrograms. Through analysis of this data, he discovered that the stars come in a limited number of distinct types and subtypes, which could be distinguished by their different spectral patterns. From this concept, he developed the first system ofstellar classification: the fiveSecchi classes. While his system was superseded by theHarvard system, he still stands as discoverer of the principle of stellar classification, which is a fundamental element ofastrophysics. His recognition ofmolecular bands ofcarbonradicals in the spectra of some stars made him the discoverer ofcarbon stars, which made one of his spectral classes.
Secchi was active inoceanography,meteorology, andphysics, as well as astronomy.
He invented theSecchi disk, which is used to measure water transparency in oceans, lakes and fish farms. He studied the climate of Rome and invented a "Meteorograph" for the convenient recording of several categories of weather data. He also studied theaurora borealis, the effects oflightning, and the cause ofhail. He organized the systematic monitoring of the Earth'smagnetic field, and in 1858 established a magnetic observatory in Rome.
Secchi also performed related technical works for the Papal government, such as overseeing placement ofsundials and repair or installation of municipal water systems. In 1854–1855, he supervised an exactsurvey of theAppian Way in Rome. This survey was later used in the topographic mapping of Italy. He supervised construction oflighthouses for the ports of the Papal States. In 1858, he traveled to France and Germany to procure the necessary projection lenses.
The lunar craterSecchi and the Martian craterSecchi are both named after him, as is a main belt asteroid, 4705 Secchi.
The two STEREO (SolarTErrestrialRElationsObservatory) spacecraft each carry an instrument package called SECCHI (SunEarthConnectionCoronal andHeliosphericInvestigation).
During his career, Fr. Secchi published about 730 papers in scientific journals. He also published a number of books.
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