Angelo Secchi

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Angelo Secchi

Angelo Secchi (born June 28, 1818 in Reggio nell'Emilia , Italy , † February 26, 1878 in Rome ) was an Italian Jesuit , physicist and astronomer . As head of the Vatican Observatory , he researched the solar corona and, from 1867, the different spectra of numerous bright stars. With their first systematic classification , Father Secchi became a pioneer of spectral analysis .


The son of a carpenter was initially supposed to become a tailor, but was soon able to show his aptitude as a scientist at the Jesuit high school. Angelo Secchi became a novice in the Jesuit order at the age of 15½ and a student at the Collegio Romano at 17 . In addition to his religious education, he was given the opportunity to study astronomy.

At the time of the revolutionary Roman Republic of Rome , the Jesuits had to leave the city and Secchi went into exile with some of his teachers . During this time he worked on the Observatories of Stonyhurst in England and the Georgetown College in Washington, DC , in the United States . After returning to Rome in 1850 he took over the management of the Vatican observatory of the Collegio Romano (Gregoriana).

Astrophysics pioneer

In 1859 Gustav Kirchhoff and Bunsen discovered that various chemical elements color the flame of a gas burner in a characteristic way, and were thus able to explain the Fraunhofer lines in the solar spectrum. When he found out about this, Secchi began the difficult task of splitting the light from stars into their color spectrum using prisms . Through the distribution of the color patterns and dark absorption lines , he determined the chemical composition of the sun and star atmosphere . In 1867 he submitted a list of over 500 fixed stars examined to the professional world, in which he initially divided the spectra into three classes :

1. white stars (prototype Wega ), 2. “colored” (similar to the sun), 3. blue stars, and two years later added type IV to this scale: “… some very strange stars, most of which are blood-red in color and have very low brightness […] yet their lines are very vivid… ”According to today's classification, it is the carbon stars . In his textbook Die Sterne , Secchi developed a type V for stars with clear hydrogen lines . Secchi's research in this field was groundbreaking, like that of William Huggins , and he and Huggins are considered to be the pioneers of spectroscopy . In further work he recognized differences in density and temperature in star types I and II and correctly suspected that types III and IV must be cooler. Its scale was slightly adapted by Hermann Carl Vogel in 1874 and was the basis for the later (still valid) Harvard classification OBAFGKM.

Further research topics

Secchi's work topics were initially also the observation of sunspots , protuberances and the development of the heliospectrograph . During the solar eclipse of 1860, he took the first photographic image of the solar corona . He also dealt with the influence of the sun on the earth's atmosphere and its electrical phenomena as well as with geomagnetism and meteorology .

He also investigated the light transmission in the Mediterranean , for which he developed a special measuring method. The Secchi disc he invented is still used in applied limnology today .

In view of his broad spectrum of scientific interests and research, which he supplemented with studies in philosophy , Angelo Secchi can also be seen as a modern representative of the ancient guild of priest astronomers.


Memorial plaque of Angelo Secchi (astronomer) in the Cortile of the Palazzo della Cancelleria, Rome

The 22-kilometer-long Secchi crater on the moon and a 50-kilometer-long mountain range, the Montes Secchi, were named in his honor . In 1992 the asteroid (4705) Secchi was named after him. The Jesuit astronomer also discovered the comet C / 1853 E1 named after him .

In 1890, the Pontifical Academy had a plaque installed in his memory in the Cortile of the Palazzo della Cancelleria in Rome.

From 1857 Secchi was a corresponding member of the Académie des Sciences in Paris, from 1865 an honorary member ( Honoray Fellow ) of the Royal Society of Edinburgh , from 1867 a corresponding member of the Bavarian Academy of Sciences and from 1877 of the Russian Academy of Sciences in Saint Petersburg .

The sculptor Giuseppe Prinzi created a bust of Secchi in Rome in 1879 .


Sui recenti progressi della meteorologia (1861)
  • Works by and about Angelo Secchi  in the German Digital Library
  • Fritz Krafft: Angelo Secchi. In: Fritz Krafft: The most important astronomers. Marix, Wiesbaden 2007
  • Joseph Pohle: P. Angelo Secchi. An image of life and culture. Bachem, Cologne 1883
  • Joseph Pohle: P. Angelo Secchi. A picture of life and culture from the nineteenth century. Second, completely revised and greatly increased edition. Bachem, Cologne 1904
  • Günter D. Roth: Cosmos of astronomy history: astronomers, instruments, discoveries . Kosmos, Stuttgart 1987

Web links

Commons : Angelo Secchi  - collection of images, videos and audio files

Individual evidence

  1. ^ Ileana Chinnici: Secchi, Angelo (1818-1878). In: Documentazione Interdisciplinare di Scienza & Fede. Retrieved June 29, 2018 (In many publications, the correct date of birth is June 29, Secchi's baptism date; June 28 is also confirmed by the Director of the Vatican Observatory, Guy Consolmagno, and the Prefect of the Congregation for the Doctrine of the Faith, Luis Ladaria , in one biographical article in the Jesuit magazine La Civiltà Cattolica ).
  2. Plankton decline across oceans as waters warm
  3. Minor Planet Circ. 20160
  4. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. (PDF file) Royal Society of Edinburgh, accessed April 6, 2020 .
  5. ^ Foreign members of the Russian Academy of Sciences since 1724. Angelo Secchi. Russian Academy of Sciences, accessed October 21, 2015 (Russian).