Editing Angelo Secchi

{{Short description|Italian priest and scientist (1818–1878)}}
{{Use dmy dates|date=January 2020}}
{{Infobox Christian leader
| type = priest
| honorific-prefix = The Reverend Father
| name = Angelo Secchi
| honorific-suffix = [[Society of Jesus|S.J.]]
| image = Angelo Secchi.jpg
| image_size = 220px
| caption = 
| birth_date = {{birth date|df=y|1818|6|28}}
| birth_place = [[Reggio Emilia]], [[Duchy of Modena and Reggio]]
| death_date = {{death date and age|df=y|1878|2|26|1818|6|29}}
| death_place = [[Rome]], [[Kingdom of Italy]]
| ordination = 12 September 1847
| residence = 
| rank = Priest
| church = [[Latin Church]]
| citizenship = 
| religion = [[Catholicism]]
| nationality = [[Italian people|Italian]]
| ethnicity = 
| module = {{Infobox scientist|embed=yes 
|field             = [[Astronomy]]
|work_institutions = Observatory of the Roman College
|known_for         = 
|prizes            = ''Légion d'honneur'', France

|footnotes         = 
|signature         =
}}
}}

'''Angelo Secchi''' {{post-nominals|post-noms=[[Society of Jesus|S.J.]]}} ({{IPA|it|ˈandʒelo ˈsekki}}; 28 June 1818 – 26 February 1878) was an [[Italians|Italian]] [[Priesthood in the Catholic Church|Catholic priest]] and [[astronomer]] from the [[Regions of Italy|Italian region]] of [[Emilia-Romagna|Emilia]].<ref>{{cite web | last = Chinnici | first = Ileana|author-link=Ileana Chinnici | url          = http://disf.org/Angelo-Secchi | title = Secchi, Angelo (1818–1878) | website = Documentazione Interdisciplinare di Scienza & Fede | access-date = 29 June 2018}} Many sources get his birthday wrong, thinking it was the 29th. He was born on the 28th, baptized on the 29th, [https://www.vofoundation.org/blog/happy-birthday-to-the-father-of-astrophysics/ writes current Vatican Observatory director] [[Guy Consolmagno]]. [[Luis Ladaria Ferrer|Luis Ladaria]], Prefect of the [[Congregation for the Doctrine of the Faith]] also states 28 June as his birthday in a [https://laciviltacattolica.com/father-angelo-secchi-jesuit-and-scientist/ biographical article] in [[La Civiltà Cattolica]].</ref> He was director of the observatory at the [[Pontifical Gregorian University]] (then called the [[Roman College]]) for 28 years. He was a pioneer in [[astronomical spectroscopy]], and was one of the first scientists to state authoritatively that the [[Sun]] is a [[star]].

==Biography==
Secchi was born in [[Reggio Emilia]], where he studied at the Jesuit [[Gymnasium (school)|gymnasium]]. At the age of 16, he entered the [[Society of Jesus|Jesuit Order]] in Rome. 
He continued his studies at the Roman College, and demonstrated great scientific ability.  In 1839, he was appointed tutor of mathematics and [[physics]] at the college. In 1841, he became professor of physics at the Jesuit College in [[Loreto (AN)|Loreto]]. In 1844, he began [[theology|theological]] studies in Rome, and was [[Holy Orders|ordained]] a priest on 12 September 1847. In 1848, due to the [[Roman Republic (19th century)|Roman Revolution]], the Jesuits were ordered to leave Rome. Secchi spent the next two years in the [[United Kingdom]] at [[Stonyhurst College]], where he met [[Alfred Weld]], the Jesuit astronomer in charge of the Stonyhurst Observatory, who may have inspired him to take up the science. He moved on to the [[United States]], where he taught for a time at [[Georgetown University]] in [[Washington, D.C.]] He also took his doctoral examination in theology there. {{sfn|Pohle|1912}}

During his stay in America, he met Commander [[Matthew Fontaine Maury]], the first director of the [[United States Naval Observatory]] in Washington. He studied with Maury and corresponded with him for many years.{{sfn|Pohle|1912}}

He returned to Rome in 1850. On the recommendation of his late colleague [[Francesco 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 the [[Sant'Ignazio Church, Rome|Sant'Ignazio Church]] (the chapel of the college).{{sfn|Chisholm|1911}} Secchi served as director until his death.<ref name="Voelkel">{{cite journal|last1=Voelkel|first1=James R.|title=Saw the Light: The early days of spectroscopy|journal=Distillations|year=2016|volume=2|issue=1|pages=24–25}}</ref>

Secchi was elected to the [[American Philosophical Society]] in 1860.<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Angelo+Sechhi |access-date=2021-01-14 |website=search.amphilsoc.org}}</ref>

His director position was challenged after 1870, when the remnant of the [[Papal States]] around Rome [[capture of Rome|was taken over]] by the [[Kingdom of Italy (1861–1946)|Kingdom 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.{{sfn|Pohle|1912}}

He died in 1878 at age 59, in Rome.

==Astronomical works==
[[File:Pincio - Secchi 1010971.JPG|thumb|bust by Giuseppe Prinzi at Pincio, Rome]]
Secchi made contributions to many areas of astronomy. 
* He revised [[Friedrich Georg Wilhelm von Struve]]'s catalog of [[double star]]s, compiling data for over 10,000 binaries.
* He discovered three [[comet]]s, including [[C/1853 E1|Comet Secchi]].
* He produced an exact map of the [[Copernicus (lunar crater)|lunar crater Copernicus]].
* He drew some of the first color illustrations of [[Mars]] and was the first to describe [[Martian canals|"channels" (''canali'' in Italian) on the planetary surface]].<ref>{{cite book | first=Michael E. | last=Bakich | date=2000 | title=The Cambridge planetary handbook | page=[https://archive.org/details/cambridgeplaneta00baki/page/198 198] | publisher=[[Cambridge University Press]] | isbn=0-521-63280-3 | url-access=registration | url=https://archive.org/details/cambridgeplaneta00baki/page/198 }}</ref>
* The first star recognized as a [[Be star]] was [[Gamma Cassiopeiae]], which Secchi observed in 1866; the first star ever observed with emission lines.<ref name=secchi>{{cite journal|doi=10.1002/asna.18670680405|title=Schreiben des Herrn Prof.Secchi, Dir. Der Sternwarte des Collegio Romano, an den Herausgeber|journal=Astronomische Nachrichten|volume=68|issue=4|pages=63–64|year=1867|last1=Secchi|first1=A.|bibcode = 1866AN.....68...63S |url=https://zenodo.org/record/1424669}}</ref>

Secchi was especially interested in the Sun, which he observed continually throughout his career.
* He observed and made drawings of solar eruptions and [[sunspot]]s, and compiled records of sunspot activity.
* In 1860 and 1870, he organized expeditions to observe [[solar eclipse]]s.
* He proved that the [[solar corona]] and coronal prominences observed during a solar eclipse were part of the Sun, and not artifacts of the eclipse.
* He discovered [[solar spicule]]s.

However, his main area of interest was [[astronomical spectroscopy]].  He invented the heliospectrograph, star spectrograph, and telespectroscope. He showed that certain [[absorption lines]] in the [[spectrum]] of the Sun were caused by absorption in the Earth's [[atmosphere]].

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 of [[stellar classification]]: the five [[Stellar classification#Secchi classes|Secchi classes]]. While his system was superseded by the [[Stellar classification#Harvard spectral classification|Harvard system]], he still stands as discoverer of the principle of stellar classification, which is a fundamental element of [[astrophysics]].  His recognition of [[Molecular band emission#Radiation from molecules|molecular bands]] of [[carbon]] [[radical (chemistry)|radical]]s in the spectra of some stars made him the discoverer of [[carbon stars]], which made one of his spectral classes.

==Other scientific and technical work==
Secchi was active in [[oceanography]], [[meteorology]], and [[physics]], as well as astronomy.

He invented the [[Secchi 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 the [[aurora borealis]], the effects of [[lightning]], and the cause of [[hail]]. He organized the systematic monitoring of the Earth's [[geomagnetism|magnetic field]], and in 1858 established a magnetic observatory in Rome.

Secchi also performed related technical works for the Papal government, such as overseeing placement of [[sundial]]s and repair or installation of municipal water systems. In 1854–1855, he supervised an exact [[surveying|survey]] of the [[Appian Way]] in Rome. This survey was later used in the topographic mapping of Italy. He supervised construction of [[lighthouse]]s for the ports of the Papal States. In 1858, he traveled to France and Germany to procure the necessary projection lenses.

==Legacy==
[[File:Angelo Secchi – Sui recenti progressi della meteorologia, 1861 - BEIC 6295977.tif|thumb|''Sui recenti progressi della meteorologia'' (1861)]]

The lunar crater [[Secchi (lunar crater)|Secchi]] and the Martian crater [[Secchi (Martian crater)|Secchi]] are both named after him, as is a main belt asteroid, 4705 Secchi.

The two STEREO ('''S'''olar '''TE'''rrestrial '''RE'''lations '''O'''bservatory) spacecraft each carry an instrument package called SECCHI ('''S'''un '''E'''arth '''C'''onnection '''C'''oronal and '''H'''eliospheric '''I'''nvestigation).

==See also==
*[[List of Jesuit scientists]]
*[[List of Roman Catholic scientist-clerics]]

==Works (incomplete)==
[[File:Le Soleil.jpg|thumb|Le Soleil: Exposé des Principales Découvertes Modernes (The Sun: Presentation of the Major Modern Discoveries). Cover.]]
During his career, Fr. Secchi published about 730 papers in scientific journals. He also published a number of books.
* {{Cite book|title=Misura Della Base Trigonometriea Eseguita Sulla Via Appia (Measurement of the Trigonometric Base Performed On the Via Appia)|date=1858|location=Rome}}
* {{Cite book|title=Il Quadro Fisico del Sistema Solare Secondo le Piu Recenti Osservazioni (The Physical Framework of the Solar System According to the Most Recent Observations)|date=1859|location=Rome}}
* {{Cite book|publisher=Tipografia delle Belle Arti|last=Secchi|first=Angelo|title=Sui recenti progressi della meteorologia|place=Roma|year=1861|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=6295977}}
* {{Cite book|title=Sulla Unitá delle Forze Fisiche (On the Unity of Physical Forces)|date=1864|location=Rome}}
* {{Cite book|title=Unità delle forze fisiche|volume=|publisher=Tipografia Forense|location=Roma|year=1864|language=it|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=12102001}}
* {{Cite book|title=Le Soleil: Exposé des Principales Découvertes Modernes (The Sun: Presentation of the Major Modern Discoveries)|date=1870|location=Paris}}
* {{Cite book|publisher=Tip. delle scienze matematiche e fisiche|last=Secchi|first=Angelo|title=Rapporto della commissione per la misura del meridiano centrale europeo negli Stati Pontifici|place=Roma|year=1871|url=http://emeroteca.braidense.it/beic_attacc/sfoglia_articolo.php?IDTestata=921&CodScheda=00AB&IDT=27&IDV=449&IDF=0&IDA=20083}}
* {{Cite book|title=Stelle|volume=|publisher=Dumolard|location=Milano|year=1877|language=it|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=12388570}}
* {{Cite book|title=Lezioni elementari di fisica terrestre|volume=|publisher=Loescher|location=Torino|year=1879|language=it|url=https://gutenberg.beic.it/webclient/DeliveryManager?pid=11808244}}

==References==
{{Reflist}}
;Attribution
*{{Cite EB1911|wstitle=Secchi, Angelo|volume=24|page=568}}
* {{cite CE1913|wstitle= Angelo Secchi |volume= 13 |last= Pohle |first= Joseph  |short=1}}

==Sources==
*{{cite book
  | last =  Maffeo
  | first = Fr. Sabino, SJ
  | others = trans. Fr. George Coyne, SJ
  | title = In the Service of Nine Popes: 100 Years of the Vatican Observatory
  | publisher = Specola Vaticana
  | location = Città del Vaticano (Vatican City)
  | date = 1991
  | isbn = 88-7761-046-8
}}

*{{cite book
  | last =  Hentschel
  | first = Klaus
  | title = Mapping the Spectrum. Techniques of Visual Representation in research and Teaching
  | publisher = Oxford Univ. Press
  | location = Oxford
  | date = 2002
  | isbn = 9780198509530
}}

*{{Cite web
  |editor-last=Chinnici
  |editor-first=Ileana
  |editor2-last=Gargano
  |editor2-first=Mauro
  |title=Tra cielo e Terra: L'avventura scientifica di Angelo Secchi
  |url=https://tracieloeterra.bicentenarioangelosecchi.it/?lang=en
  |publisher=Comitato Nazionale per il Bicentenario della Nascita di Angelo Secchi
  |location=Roma
  |year=2018
  |access-date=26 May 2019
  |archive-date=26 May 2019
  |archive-url=https://web.archive.org/web/20190526142705/https://tracieloeterra.bicentenarioangelosecchi.it/?lang=en
  |url-status=dead
  }}

*{{cite book
  | last =  Chinnici
  | first = Ileana
  | title = Decoding the Stars: A Biography of Angelo Secchi, Jesuit and Scientist
  | publisher = Brill
  | location = Leiden/Boston
  | date = 2019
  | isbn = 9789004387331
}}

==External links==
* {{wikisource author-inline}}
* {{DBI |title= SECCHI, Angelo Francesco Ignazio Baldassarre |url=https://www.treccani.it/enciclopedia/angelo-francesco-ignazio-baldassarre-secchi_(Dizionario-Biografico)|last= Chinnici|first= Ileana|volume= 91}}

{{Authority control}}

{{DEFAULTSORT:Secchi, Angelo}}
[[Category:1818 births]]
[[Category:1878 deaths]]
[[Category:People from Reggio Emilia]]
[[Category:19th-century Italian astronomers]]
[[Category:19th-century Italian Jesuits]]
[[Category:Italian meteorologists]]
[[Category:People educated at Stonyhurst College]]
[[Category:Foreign members of the Royal Society]]
[[Category:Members of the French Academy of Sciences]]
[[Category:Jesuit scientists]]
[[Category:International members of the American Philosophical Society]]