Vatican Observatory

File:Specola1.jpg
Organization	Holy See
Observatory code	036
Location	Castel Gandolfo, Metropolitan City of Rome Capital, Lazio, Italy
Coordinates	41°44′50″N 12°39′02″E / 41.747222222222°N 12.650555555556°E
Altitude	430 m (1,410 ft)
Established	1930
Website	www.vaticanobservatory.org/,%20https://www.vaticanobservatory.va/
Vatican Observatory Location within Italy
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The Vatican Observatory (Italian: Specola Vaticana) is an astronomical research and educational institution supported by the Holy See. Originally based in the Roman College of Rome, the Observatory is now headquartered in Castel Gandolfo, Italy and operates a telescope at the Mount Graham International Observatory in the United States.

History

The Church has had a long-standing interest in astronomy, due to the astronomical basis of the calendar by which holy days and Easter are determined. For instance, the Gregorian Calendar, promulgated in 1582 by Pope Gregory XIII, was developed by Aloysius Lilius and later modified by Christoph Clavius at the Collegio Romano from astronomical data. The Gregorian Tower was completed in 1580 for his purpose, designed by Bolognese architect Ottaviano Nonni.

In the 18th century, the Papacy actively supported astronomy, establishing the Observatory of the Roman College in 1774. In 1787–1789, the Specola Vaticana in the Tower of the Winds within the Vatican was established under the direction of Msgr. Filippo Luigi Gilii (1756–1821). When Msgr. Gilii died, the Specola was closed down because it was inconvenient for students in the city because the dome of St. Peter's obstructed its view. Its instruments were transferred to the College Observatory. A third facility, the Observatory of the Capitol, was operated from 1827 to 1870.

Father Angelo Secchi SJ relocated the College Observatory to the top of Sant'Ignazio di Loyola a Campo Marzio (Church of St. Ignatius in Rome). In 1870, with the capture of Rome, the College Observatory fell into the hands of the Italian Government. Out of respect for his work, however, Father Secchi was permitted to continue using the Observatory. After Secchi's death in 1878 the Observatory was nationalized by the Italian government and renamed the Regio Osservatorio al Collegio Romano ("Royal Observatory at the Roman College"), ending astronomical research in the Vatican.

In 1891, however, Pope Leo XIII issued a Motu proprio re-founding the Specola Vaticana (Vatican Observatory) and a new observatory was built on the walls at the edge of the Vatican. The new Vatican Observatory remained there for the next forty years.

In the late nineteenth-century the Vatican Observatory was part of a group of top astronomy institutions from around the world which worked together to create a photographic "Celestial Map" ("Carte du Ciel") and an "astrographic" catalog pinpointing the stars' positions. Italian astronomer Father Francesco Denza led the Vatican's contribution to the project until his death in 1894. In the early twentieth century, Father John Hagen took over the project and recruited a group of nuns from the Sisters of the Holy Child Mary to work on the necessary recording and calculations. The nuns, Sisters Emilia Ponzoni, Regina Colombo, Concetta Finardi and Luigia Panceri, helped map and catalog nearly half a million stars.

By the 1930s, the smoke and sky-glow of the city had made it impossible to conduct useful observations in Rome. Pope Pius XI relocated the Observatory to Castel Gandolfo, which is 25 kilometres (16 mi) southeast of Rome. By 1961, the same problems with light pollution made observing difficult at Castel Gandolfo. The Observatory then established the Vatican Observatory Research Group (VORG), with offices at the Steward Observatory of the University of Arizona in Tucson, Arizona.

D.K.J. O'Connell produced the first color photographs of a green flash at sunset in 1960. In 1993, VORG completed construction of the 1.8 metres (71 in) Vatican Advanced Technology Telescope, which is at Mount Graham near Safford, Arizona.

The Observatory's headquarters remain in Italy at Castel Gandolfo. In early 2008, the Vatican announced that the Observatory would be relocated to a former convent a mile away from the castle as part of a general reconstruction of the Papal residence. Its former space would be used to provide more room for the reception of diplomatic visitors. The old quarters in the castle were cramped and very poorly laid out for the Observatory's use. VORG research activities in Arizona continued unaffected.

Brother Guy Consolmagno was Director of the Observatory for ten years, from 2015 to 2025 and was replaced by Father Anthony D’Souza, S.J. on 19 September 2025.

Locations and Equipment

Castel Gandolfo

In Castel Gandolfo, there are four observatory domes (“Specola”), two of which are located on the roof of the Papal Palace and two in the gardens of the Papal Palace. These instruments now only partially meet modern astronomical requirements.

The two wooden domes on the roof of the Papal Palace contain:

• Zeiss Double Astrograph, consisting of a refractor (aperture 40 cm, focal length 240 cm) and a reflecting telescope (aperture 60 cm, Newtonian focal length 200 cm), together with two finders and a guiding telescope, all rigidly mounted on the same polar axis. Conceived as the observatory’s main instrument, it was inaugurated in 1935.
• Zeiss visual refractor telescope (aperture 40 cm, focal length 600 cm), also inaugurated in 1935. Zeiss supplied a set of nine eyepieces and various accessories; the instrument was also equipped with a Graff photometer for observing variable stars and a micrometer for measuring double stars.

The two connected domes in the gardens of the Papal Palace contain:

• Carte du Ciel telescope, consisting of a double refractor (astrograph: aperture 33 cm, focal length 343 cm; collimator: aperture 20 cm, focal length 360 cm), which was acquired for the Vatican Observatory’s participation in the international Carte du Ciel project to create a photographic star atlas. The instrument was installed in 1891 on the Tower of St. John (part of the Leonine Wall) in the Vatican Gardens and was moved to Castel Gandolfo in 1942. The last photographic plates for the Carte du Ciel project were taken in 1953.
• Schmidt reflecting telescope by Hargreaves & Thomson (aperture 98 cm, focal length 240 cm), inaugurated in 1957.

Mount Graham

Since 1981, the Vatican Observatory has operated the Vatican Observatory Research Group at the University of Arizona, along with additional collaborations with other observatories, primarily in the United States. Since 1993, the Vatican Observatory Research Group has been associated with the VATT (Vatican Advanced Technology Telescope), an observatory with a 1.8-meter telescope located on Mount Graham in Arizona.

People

Leadership

• Francesco Denza, B (1891–1894)
• Giuseppe Lais, CO (1894–1898)
• Ángel Rodríguez de Prada, OSA (1898-1905)
• Johann Georg Hagen, SJ (1906–1930)
• Johan Stein, SJ (1930–1951)
• Daniel Joseph Kelly O'Connell, SJ (1952–1971)
• Patrick Treanor, SJ (1971–1978)
• George Coyne, SJ (1978–2006)
• José Gabriel Funes, SJ (19 August 2006 – 18 September 2015)
• Guy Consolmagno, SJ (18 September 2015 –19 September 2025)
• Richard Anthony D’Souza, SJ (19 September 2025–present)

Other notable people

Prof Sister Natalia Zotov OP SFCC spent two summers at the observatory, the first woman to work there as an astronomer.

In 2008, the Templeton Prize was awarded to cosmologist Fr. Michał Heller, a Vatican Observatory Adjunct Scholar. In 2010, the George Van Biesbroeck Prize was awarded to former observatory director, the American Jesuit, Fr. George Coyne.

See also

• Archaeoastronomy
• Catholic Church and science § Vatican Observatory
• Scientific Perspectives on Divine Action
• Vatican Advanced Technology Telescope
• List of astronomical observatories
• List of Jesuit sites
• Pietro Maffi

From the 1913 Catholic Encyclopedia

The Vatican Observatory now bears the official title, "Specola Astronomica Vaticana". To understand its history it is necessary to remark that the designations osservatorio or specola are not restricted to astronomy, but may mean any elevated locality from which aerial phenomena are observed. From this point of view the history of the Specola Vaticana has passed through four successive stages.

Gregorian Tower and the early observatory

(1) The first period of the Vatican Observatory is thus described in the Motu Proprio of 1891 by Leo XIII:

Gregory XIII ordered a tower to be erected in a convenient part of the Vatican buildings, and to be fitted out with the greatest and best instruments of the time. There he held the meetings of the learned men to whom the reform of the calendar had been entrusted. The tower stands to this day, a witness to the munificence of its author. It contains a meridian line by Ignazio Danti of Perugia, with a round marble plate in the centre adorned with scientific designs. When touched by the rays of the sun that are allowed to enter from above, the designs demonstrate the error of the old reckoning and the correctness of the reform.

The first half of this narration is based upon a tradition supported by Gilii and Calandrelli (see LILIUS); it is connected with the Vatican Observatory, at least as far as the locality is concerned. The tower is 73 metres above sea level and stands over the museum and library, between the courtyards Belvedere and della Pigna. It is often called the "Tower of the Winds"

Gilii, Leo XIII, and Pius X

(2) The second period of the Vatican Observatory deals mainly with the person of Mgr. Filippo Luigi Gilii, whose life has been written by Lais. Gilii was born in Corneto in 1756, and died in Rome, in 1821, a beneficed clergyman of St. Peter's Basilica. He was a universal genius, well versed in physics and in biology, in archeology and in the Hebrew language. The Gregorian Tower was then in charge of the Vatican librarian, to which office Cardinal Zelada had been appointed in 1780. Zelada wished to honour the traditions of the tower by devoting its upper part to an observatory. In 1797 he obtained the sanction of Pius VI, and placed over the entrance to the tower the Latin inscription Specula Vaticana. The upper story was fitted up with meteorological and magnetic instruments, with a seismograph, a Dolland telescope, a small transit and pendulum clock, and the observatory was given in charge of Mgr. Gilii. From 1800 to 1821 Gilii made an uninterrupted series of meteorological observations, reading the instruments twice a day (after 6 a. m. and 2 p, m.), according to the programme of the Mannheim Meteorological Society. The observations of about seven years of the long series are published, while the rest are in great part preserved as manuscripts in the Vatican Library. There are also deposited astronomical observations of eclipses, comets, Jupiter's satellites, and of a transit of Mercury. Gilii's scientific activity extended beyond the Vatican Observatory and beyond Rome. The meridian line in front of St. Peter's, with the obelisk as gnomon and the readings of the seasons by the length of the shadow, is due to him; so are also the signs on the floor of St. Peter's Basilica, indicating the lengths of the greatest churches of the world, likewise the two old clocks of French and Italian style, in the front of the basilica, and finally the first lightning rod on St. Peter's cupola. Similar memories of him exist in various churches and cities of Italy. The tombstone in Ara Co li calls him a man "mitissimi ingenii, modestiæ singularis, pius". At the death of Gilii the Vatican Observatory was discontinued, for the following reason: Pius VII and Leo XII raised the standard of studies in the papal states. The latter pope, in his Apostolic letter, "Quod divina sapientia", gave instructions about observatories, publications, and intercourse with foreign scientists. In 1787 the observatory at the Roman College had been founded, under Calandrelli, and was declared preferable to the Vatican, as more accessible to students in the city, and not obstructed by the great cupola of St. Peter's (Giornale Arcadico, II, p. 407). On the advice of Father Boscovich the instruments were then transferred from the Gregorian Tower to the Roman College.

(3) The revival of the Vatican Observatory in its third period was occasioned, on the one hand, by the loss to the Church of the Roman College and its observatory in 1870, and on the other, by the exposition of instruments presented to Leo XIII by the Italian clergy for the celebration of his golden jubilee of priesthood, in 1888. The Barnabite Father Denza, well-known as founder of the Italian Meteorological Society, then proposed to Leo XIII to preserve the instruments in the Gregorian Tower, and to restore that locality to its former purposes. The plan was accepted and a series of the best instruments was procured, partly from donations by Hicks in London, partly by purchase of self-registering apparatus from Richard in Paris. From the observatory of the late Marquis of Montecuccoli in Modena, of which Denza had been director, a four-inch equatorial, a three-inch transit instrument, and four pendulum clocks with two chronometers, were acquired. Father Denza had still broader plans. The year before in 1887, Mouchez had organized the cooperation of a number of observatories for continuing Argelander's observations to fainter magnitudes by means of photography. At the second meeting of the committee in Paris, in 1889, Denza declared his intention to join in the work. For this purpose, Leo XIII ceded to the Vatican Observatory a second tower, more than 400 metres distant from the Gregorian. It is the western of the two towers remaining from the Leonine Fortress, which had been built for defence against the Saracens in 848-53. With a diameter of 17 metres and a thickness of 4.5 metres in the lower walls, it seemed large and strong enough to support the thirteen-inch photographic refractor which was ordered from Gauthier in Paris. During the four years following, the observatory remained in charge of the vice-director, Father Lais, of the Oratory who has conducted the photographic work from the beginning, all at his own expense. From 1898 until 1905 the directorship was in the hands of the Augustinian Father Rodriguez, a specialist in meteorology. Seven volumes were published during the third period of the observatory, four under Denza, the fifth under Lais, and the last two under Rodriguez.

(4) The fourth and present period of the Vatican Observatory began with the appointment in November, 1904, by Pius X of Archbishop (now Cardinal) Maffi as President of the Specola. His first step was to remedy the great difficulty caused by the separation of the two towers. According to his plans, the Gregorian Tower was to be abandoned to historical archives, and the second round tower of the old Leonine Fortress, with the adjoining summer residence of Leo XIII, was to be given over to astronomy. The two old towers were to be connected with each other by a passage over the fortification wall, with an iron bridge spanning a gap of 85 metres in length. For carrying out these plans, the author of the present article was designated in the audience given to Cardinal Maffi on 14 March, 1906, and officially appointed on 26 April. The fortification wall, a thousand years old, which extends about 400 metres, is now crowned with four rotary domes, covering the astrographic refractor in the Leonine Tower, and a new sixteen-inch visual telescope in the second tower, called Torre Pio X. A four-inch equatorial stands on a half round bastion, at the west end of the bridge, and a photoheliograph at the east end of the old wall, over the barracks of the gendarmes. The old transit instrument is mounted on a vault over the main walls of the new residence. After the material restoration of the observatory, the main problems were a library and the measuring of the astrographic plates. The rich meteorological library was consigned to the Pontifical Academy Lincei, and the old meteorological and seismic instruments were mainly sent to the observatory in Valle di Pompei, An astronomical library is now filling two rooms of the new residence; old treasures were secured to it by the loan of the scientific collection from the Vatican Library, the latter confining itself to historical and literary branches. The astrographic plates are being measured with two new Repsold machines, which are placed in a neighbouring convent, in charge of three Sisters. For nearly four years the director enjoyed the cooperation of Father Stein, S.J., by which it was possible to publish the first three numbers of the new series, besides minor essays, and the last two series of the atlas of variable stars. At the reunion of the Astrographic Congress at Paris in 1909, P. Lais presented thirty charts reproduced by himself on silver-bromide paper.

DENZA, La Nuova Specola Vaticana in Atti, Acad. Pont. N. Lincei XLIII (1889); ZAHM, The Observatory of the Vatican in The Cosmopolitan (1895), well illustrated but not exact in all details; STEIN, Restauri della Specola Vaticana in Rivista di Fisica etc., IX (Pavia, 1908); HAGEN, Vaticanische Sternwarte in V. J. S. Astron. Ges., XLV (1910); MAFFI, Specula Vaticana, Inaugurazione (Rome, 1910); PARR, The Vatican Observatory of Today in Knowledge (1911), correct, except the additions by the editors.

Bibliography

• Sabino Maffeo: The Vatican Observatory. In the Service of Nine Popes, Vatican Observatory Publications, 2001.

External links

• Official website