Angelo Secchi

Fr. Angelo Secchi SJ (Italian pronunciation: [ˈˈandʒelo ˈsekki]; 28 June 1818[1] – 26 February 1878) was an Italian astronomer. 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.

Angelo Secchi
Angelo Secchi
Born28 June 1818
Reggio Emilia
Died26 February 1878 (aged 59)
AwardsLégion d'honneur, France
Scientific career
InstitutionsObservatory of the Roman College


Secchi was born in Reggio Emilia, where he studied at the Jesuit gymnasium. At the age of 16, he entered the 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. In 1844, he began theological studies in Rome, and was ordained a priest on 12 September 1847. In 1848, due to the Roman Revolution, the Jesuits had to leave Rome. Fr. Secchi spent the next two years in the United Kingdom at Stonyhurst College, and the United States, where he taught for a time at Georgetown University in Washington, DC. He also took his doctoral examination in theology there. [2]

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.[2]

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 (the chapel of the College).[3] Secchi served as Director until his death.[4]

His position was challenged after 1870, when the remnant of the Papal States around Rome was taken over by the 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.[2]

He died in 1878 at age 59, in Rome.

Astronomical works

Pincio - Secchi 1010971
bust by Giuseppe Prinzi at Pincio, Rome

Secchi made contributions to many areas of astronomy.

Secchi was especially interested in the Sun, which he observed continually throughout his career.

  • He observed and made drawings of solar eruptions and sunspots, and compiled records of sunspot activity.
  • In 1860 and 1870, he organized expeditions to observe solar eclipses.
  • 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 spicules.

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 Secchi classes. While his system was superseded by the Harvard system, he still stands as discoverer of the principle of stellar classification, which is a fundamental element of astrophysics. His recognition of molecular bands of carbon radicals 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 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 sundials and repair or installation of municipal water systems. In 1854-1855, he supervised an exact survey of the Appian Way in Rome. This survey was later used in the topographic mapping of Italy. He supervised construction of lighthouses for the ports of the Papal States. In 1858, he traveled to France and Germany to procure the necessary projection lenses.


Angelo Secchi – Sui recenti progressi della meteorologia, 1861 - BEIC 6295977
Sui recenti progressi della meteorologia (1861)

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

The two STEREO (Solar TErrestrial RElations Observatory) spacecraft each carry an instrument package called SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation).

See also

Works (incomplete)

Le Soleil
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.

  • Misura Della Base Trigonometriea Eseguita Sulla Via Appia (Measurement of the Trigonometric Base Performed On the Via Appia). Rome. 1858.
  • Il Quadro Fisico del Sistema Solare Secondo le Piu Recenti Osservazioni (The Physical Framework of the Solar System According to the Most Recent Observations). Rome. 1859.
  • Secchi, Angelo (1861). Sui recenti progressi della meteorologia. Roma: Tipografia delle Belle Arti.
  • Sulla Unitá delle Forze Fisiche (On the Unity of Physical Forces). Rome. 1864.
  • Le Soleil: Exposé des Principales Découvertes Modernes (The Sun: Presentation of the Major Modern Discoveries). Paris. 1870.
  • Le Stelle (The Stars). Milan. 1877.
  • Lezioni Elementari di Fisica Terrestre (Elementary Lessons In Terrestrial Physics). Turin And Rome. 1879.


  1. ^ Chinnici, Ileana. "Secchi, Angelo (1818 - 1878)". Documentazione Interdisciplinare di Scienza & Fede. Retrieved 2018-06-29. Many sources get his birthday wrong, thinking it was the 29th. He was born on the 28th, baptized on the 29th, writes current Vatican Observatory director Guy Consolmagno. Luis Ladaria, Prefect of the Congregation for the Doctrine of the Faith also states June 28th as his birthday in a biographical article in La Civiltà Cattolica.
  2. ^ a b c Pohle 1913.
  3. ^ Chisholm 1911.
  4. ^ Voelkel, James R. (2016). "Saw the Light: The early days of spectroscopy". Distillations. 2 (1): 24–25.
  5. ^ Bakich, Michael E. (2000). The Cambridge planetary handbook. Cambridge University Press. p. 198. ISBN 0-521-63280-3.


  • Maffeo, Fr. Sabino, SJ (1991). In the Service of Nine Popes: 100 Years of the Vatican Obervatory. trans. Fr. George Coyne, SJ. Città del Vaticano (Vatican City): Specola Vaticana. ISBN 88-7761-046-8.
  • Hentschel, Klaus (2002). Mapping the Spectrum. Techniques of Visual Representation in research and Teaching. Oxford: Oxford Univ. Press. ISBN 9780198509530.

External links

1818 in science

The year 1818 in science and technology involved some significant events, listed below.

1860 in science

The year 1860 in science and technology involved some significant events, listed below.

306 Unitas

Unitas (minor planet designation: 306 Unitas) is a typical main belt asteroid that was discovered by Elia Millosevich on 1 March 1891 in Rome. The asteroid was named by the director of the Modena Observatory in honor of the Italian astronomer Angelo Secchi. It is classified as an S-type asteroid.

In the late 1990s, a network of astronomers worldwide gathered light curve data that was ultimately used to derive the spin states and shape models of 10 new asteroids, including (306) Unitas. The computed shape model for this asteroid is regular, while the light curve displays two maxima per rotation. Lightcurve data has also been recorded by observers at the Antelope Hill Observatory, which has been designated as an official observatory by the Minor Planet Center.Measurements of the thermal inertia of 306 Unitas give an estimate range from 100 to 260 m−2 K−1 s−1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.Although 306 Unitas has an orbit similar to the Vesta family asteroids, it was found to be an unrelated interloper on the basis of its non-matching spectral type.

Orbir diagram of 306 Unitas


Angelo is an Italian masculine given name and surname meaning "angel", or "messenger".

Be star

Be Stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as Classical Be Stars, is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer emission lines.

Carbon star

A carbon star is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes all the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds, giving the star a "sooty" atmosphere and a strikingly ruby red appearance. There are also some dwarf and supergiant carbon stars, with the more common giant stars sometimes being called classical carbon stars to distinguish them.

In most stars (such as the Sun), the atmosphere is richer in oxygen than carbon. Ordinary stars not exhibiting the characteristics of carbon stars but cool enough to form carbon monoxide are therefore called oxygen-rich stars.

Carbon stars have quite distinctive spectral characteristics, and they were first recognized by their spectra by Angelo Secchi in the 1860s, a pioneering time in astronomical spectroscopy.

Catholic Church and science

The relationship between the Catholic Church and science is a widely debated subject. Historically, the Catholic Church has often been a patron of sciences. It has been prolific in the foundation of schools, universities and hospitals, and many clergy have been active in the sciences. Historians of science such as Pierre Duhem credit medieval Catholic mathematicians and philosophers such as John Buridan, Nicole Oresme, and Roger Bacon as the founders of modern science. Duhem found "the mechanics and physics, of which modern times are justifiably proud, to proceed by an uninterrupted series of scarcely perceptible improvements from doctrines professed in the heart of the medieval schools." Yet, the conflict thesis and other critiques emphasize historical or contemporary conflict between the Catholic Church and science, citing in particular the trial of Galileo as evidence. For its part, the Catholic Church teaches that science and the Christian faith are complementary, as can be seen from the Catechism of the Catholic Church which states in regards to faith and science:

Though faith is above reason, there can never be any real discrepancy between faith and reason. Since the same God who reveals mysteries and infuses faith has bestowed the light of reason on the human mind, God cannot deny himself, nor can truth ever contradict truth. ... Consequently, methodical research in all branches of knowledge, provided it is carried out in a truly scientific manner and does not override moral laws, can never conflict with the faith, because the things of the world and the things of faith derive from the same God. The humble and persevering investigator of the secrets of nature is being led, as it were, by the hand of God in spite of himself, for it is God, the conserver of all things, who made them what they are.

Catholic scientists, both religious and lay, have led scientific discovery in many fields. From ancient times, Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals and the Church remains the single largest private provider of medical care and research facilities in the world. Following the Fall of Rome, monasteries and convents remained bastions of scholarship in Western Europe and clergymen were the leading scholars of the age – studying nature, mathematics, and the motion of the stars (largely for religious purposes). During the Middle Ages, the Church founded Europe's first universities, producing scholars like Robert Grosseteste, Albert the Great, Roger Bacon, and Thomas Aquinas, who helped establish the scientific method.During this period, the Church was also a great patron of engineering for the construction of elaborate cathedrals. Since the Renaissance, Catholic scientists have been credited as fathers of a diverse range of scientific fields: Nicolaus Copernicus (1473-1543) pioneered heliocentrism, Jean-Baptiste Lamarck (1744-1829) prefigured the theory of evolution with Lamarckism, Friar Gregor Mendel (1822-1884) pioneered genetics, and Fr Georges Lemaître (1894-1966) proposed the Big Bang cosmological model. The Jesuits have been particularly active, notably in astronomy. Church patronage of sciences continues through institutions like the Pontifical Academy of Sciences (a successor to the Accademia dei Lincei of 1603) and Vatican Observatory (a successor to the Gregorian Observatory of 1580).

Giuseppe Prinzi

Giuseppe Prinzi (1825–1895) was an Italian sculptor.

La Superba

La Superba (Y CVn, Y Canum Venaticorum) is a strikingly red giant star in the constellation Canes Venatici. It is a carbon star and semiregular variable.

Montes Secchi

Montes Secchi (Latin for "Secchi Mountains") is a minor range of lunar mountains located near the northwestern edge of Mare Fecunditatis. This roughly linear formation of low ridges grazes the northwestern outer rim of the crater Secchi, the formation from which this range gained its name. This crater is named after Angelo Secchi, a 19th-century Italian astronomer. The ridges trend from southwest to northeast.

In the vicinity of Montes Secchi is Mount Marilyn, a distinctly triangular mountain formation. It was named in 1968 by Apollo 8 astronaut Jim Lovell, after his wife. The name was not approved by the IAU until July 26, 2017. Before its approval, it was known as Secchi Theta.

The selenographic coordinates of the range midpoint are 2.4° N, 43.6° E, and they lie within a diameter of 50 km. This is smaller than the diameter of the crater Taruntius, located to the northeast of the mountains.

Pietro Tacchini

Pietro Tacchini (March 21, 1838 – March 24, 1905) was an Italian astronomer.

He was born and raised in Modena, Italy. He studied engineering at the University of Padova. At the age of 21, he was appointed the director of a small observatory in Modena. By 1863 he became the Primo Astronomo Aggiunto, or director of the observatory, at Palermo, Italy. He remained there until 1879, and focused most of his attention on observations of the Sun.

In 1865 he founded the specialist physical astronomy journal, Memorie della Società degli Spettroscopisti, and remained the editor until 1905. (This publication later became the Memorie della Società Astronomica Italiana in 1920.)

Tacchini established an observation network with other Italian astronomers to spectroscopically examine the sun at about the same time daily. He likewise organized an observatory in Calcutta to watch the sun when conditions were unfavorable in Italy. In 1874 he led an expedition to Muddapur, India to observe the transit of Venus across the sun.

In 1879 he was summoned to Rome where he succeeded Angelo Secchi at the Osservatorio del Collegio Romano. In 1881 he became head of the Ufficio Centrale di Meteorologia.

Due to his influence, the Bellini Observatory was completed on Mount Etna where Pietro believed that the high altitude would improve the spectroscopic observations of the sun, and potentially allow direct observations of the solar corona without an eclipse. He also recommended the construction of the Catania Observatory in 1885.

The crater Tacchini on the Moon is named for him, as well as the asteroid 8006 Tacchini.

Rimae Secchi

Rimae Secchi is a system of rilles on the Moon, in northwestern Mare Fecunditatis. They are approximately 40 km long and run along the shore of the mare.

Rimae Secchi are named after the nearby crater Secchi which, in turn, is named after an Italian astronomer Angelo Secchi. The name of the rilles was approved by the International Astronomical Union in 1985. In 1974, the name Fossae Secchi was proposed on a map published by the US Defense Mapping Agency, but this name was not adopted (on the Moon, the term Rima is traditionally used instead of Fossa). Before this, during preparation to Apollo 8 and 10 flight, the rilles were informally nicknamed Apollo Rille.The northern end of Rimae Secchi is Y-shaped, and the southern part consists of several separate troughs. Rimae Secchi run along the northwestern rim of a ghost crater (lava-filled crater) of approximately 85 km diameter. The rilles are centered at 1.0°N 44.1°E / 1.0; 44.1.

The northern part of Rimae Secchi is surrounded with a dark halo, probably pyroclastic deposits like volcanic ash. Such deposits are common near the edges of lunar maria, including several areas in Mare Fecunditatis.To see this feature, a telescope with an aperture of 20 cm or larger is needed.

Secchi (Martian crater)

Secchi is a crater in the Hellas quadrangle of Mars, located at 58.3° south latitude and 258.1° west longitude. it is 223 km in diameter and was named after Angelo Secchi, an Italian astronomer (1818–1878).

Secchi (lunar crater)

Secchi is a small lunar impact crater formation on the northwest edge of Mare Fecunditatis. It was named after the 19th-century Italian astronomer Angelo Secchi. To the northeast is the crater Taruntius. The western rim is joined with a section of the minor Montes Secchi range. The rim of this crater has been opened in the northern and southern ends, leaving two curved ridges facing each other across the crater floor. To the south is a pair of rilles designated the Rimae Secchi. These lie near the edge of the mare, and have a combined length of about 40 kilometers.

Secchi disk

The Secchi disk, as created in 1865 by Angelo Secchi, is a plain white, circular disk 30 cm (12 in) in diameter used to measure water transparency or turbidity in bodies of water. The disc is mounted on a pole or line, and lowered slowly down in the water. The depth at which the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity. Since its invention, the disk has also been used in a modified, smaller 20 cm (8 in) diameter, black and white design to measure freshwater transparency.

Spicule (solar physics)

In solar physics, a spicule is a dynamic jet of about 500 km diameter in the chromosphere of the Sun. It moves upwards at about 20 km/s from the photosphere. They were discovered in 1877 by Father Angelo Secchi of the Observatory of Roman Collegium in Rome.

Stonyhurst Observatory

The Stonyhurst Observatory is a functioning observatory and weather station at Stonyhurst College in Lancashire, England. Built in 1866, it replaced a nearby earlier building, built in 1838, which is now used as the Typographia Collegii.

The records of temperature, which continue to be taken there, began in 1846 and are one of the oldest continuous daily records in the world. (the very oldest continuous daily temperature records was taken at the Old Stockholm Observatory since 1756). In 2004, Stonyhurst replaced Ringway as one of four weather stations used by the Met Office to provide central England temperature data (CET); revised urban warming and bias adjustments have since been applied to the Stonyhurst data.During the course of the twentieth century, the observatory fell out of use for astronomical purposes and its telescope, parts of which dated to the 1860s, was sold after the Second World War. When its private owner came to re-sell it, the College was able to buy it back and restore it to its original home. See: Stonyhurst Refractor

The observatory is currently run by Classics master Fintan O' Reilly, who also teaches GCSE astronomy. Occasionally access is permitted to the observatory for visitors.

Villa Spedalotto

The Villa Spedalotto is the country home of the Paternò di Spedalotto family. The villa is situated on a hill surrounded by olive groves at Bagheria, near Palermo in Sicily. As all the Villas in Bagheria, it was built as a country house, and was traditionally used by the family only during the spring and autumn. While considered a national monument, it remains a private residence.

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