Telescope for Villa Barberini

The Galileo Foundation


“Pilgrims and tourists may now cross the threshold of the Pontifical Villa of Castel Gandolfo to visit the Barberini Gardens.” It is this decision in September 2015 by Pope Francis that granted the public access to what had been the papal suburban residency since the time of Urban VIII. An extraterritorial zone of the Holy See, the Pontifical Villa of Castel Gandolfo spans an area of approximately fifty-five hectares, situated in the Alban Hills. While the Apostolic Palace is located on the ancient city of Albalonga, the birthplace of Rome’s legendary twin founders, Romulus and Remus, Castel Gandolfo resides directly on one of the most famous ancient constructions: that of the grand residency of Emperor Domitian (81-96 A.D.). Since September 11, 2015, the Vatican Museums have welcomed thousands of visitors within the gardens of Villa Barberini as well as the area including the farm, all reachable by car or railway. Two astronomical domes on the terrace of the Apostolic Palace of Castel Gandolfo remain an outstanding part of history, but are not yet open to the public.


Particular attention has been made to astronomy by the papacy throughout the last five centuries. One needs simply to look nearby to the Vatican Museums; between the Pinecone Courtyard and Belvedere Courtyard resides the Tower of the Winds, now known as the Vatican Observatory. Although simply one tower, it bears a great significance in astronomical history. Our story starts with how the solar calendar of Juilius Cesear from 46 B.C. needed reform; Pope Gregory XIII (1572-1585) was the man to do it. As it is widely known, it was precisely Pope Gregory XIII who also appointed a congregation composed of mathematical experts, cartographers, and above all astronomers, in order to formulate that which was to eventually become the Gregorian Calendar. Thanks to these experts as well as the Dominican priest Ignazio Danti -one of the greatest cosmographers of his day and to whom the cartoons of the Gallery of the Maps are attributable -a sundial was fashioned in the Tower of the Winds in order to execute the task. In one room of the tower, there are also beautiful allegorical frescoes by Pomarancio. The Wind is the protagonist, transformed into an archetype of the oriental and Lutheran heresies which hovers directly next to the Biblical passage “ab Aquilone pandetur omne malum” or “from the North Wind comes every disgrace.” This same wind, however, also becomes an allusion to the four cardinal directions and simultaneously an allegory of the four seasons. Meanwhile, the floor bears the image of the sundial, thus giving the room its namesake: the Sundial Room, or Meridian Room.


To understand how the sundial functions, it is necessary to observe in the fresco the Spirit of God who, blowing, generates the storm. This is because, only upon a closer look at the divine figure, one notes the presence of a hole through which sunlight is permitted to enter. At a given time of day according to the height of the sun from the horizon, the beam of light illuminates a different point of the sundial. A plaque in the room commemorates the moment on March 21, 1580, when the Pope, upon visiting the room to observe the sundial, noticed that there was about a ten-day difference between the time recorded on the Julian calendar and that which was effectively portrayed on the sundial itself. His congregation of experts subsequently reported their recommendation to skip ahead 10 days in order to recuperate the lost time on the Julian calendar, and to also change the rules of the leap years. On March 1, 1582 the papal decree Inter Gravissimas was sanctioned, which authorized the reform of the Julian Calendar and gave way to the Gregorian calendar – the latter of which remains in use to this day.
The Tower of the Winds function as an astronomical observatory turned over form the hands of the papacy to that of the Roman College, founded by Saint Ignatius of Loyola. After all, St. Ignatius had, thanks to the munificence of Pope Gregory XIII, quickly reached the highest level of study in mathematics, physics, and astronomy. Father Clavius, one of the numerous scientists who worked there, was committed to authenticating Galileo’s discoveries and, above all, to convince the ecclesial authorities of their scientific validity. In 1611, Galileo himself was invited to the Roman College to explain his discoveries regarding the celestial bodies’ movements found through the use of the telescope.

Cardinal Maffeo Barberini (later Pope Urban VIII) enters our stage again, this time as one of the great defenders of Galileo. He supported the astronomer so much that when Galileo published his book The Assayer, he dedicated it to the Pope, who validated it positively and had encouraged Galileo to continue with his mathematically based studies on the systems of the universe. About the middle of the 18th century, the inventor of the micrometer ring, Roger J. Boscovich, proposed to erect a new observatory. The Calandrelli Tower was constructed in 1787 and can still be seen from the Roman College piazza. From this tower several years later, Pope Pio VII observed a very large sunspot. Fascinated by the incident, he brought an achromatic telescope and a grandfather clock to Rome after his Parisian sojourn to crown Napoleon. His acquired instrumentation sparked the real onset of astronomical studies. Years later, several comets and two of Saturn’s moons were discovered from Calandrelli, sparking the Tower’s fame worldwide. Other astronomical scientific discoveries at the Vatican included studies of binary stars, planet and comet nebulae research, behavior of the sun and stars, the physical forces exerted on the planets, terrestrial magnetism, and meteorology. In 1873, following the suppression of the Papal States, the Roman College and its observatory were expropriated and declared property of the Italian State. Thus, any astronomical activities carried out under the papal auspices continued only in the Tower of the Winds. In 1888, Father Francesco Denza, founder of the Italian Meteorological Society, reignited astronomical efforts at the Observatory of the Winds. He received permission to proceed from Pope Leo XIII at the time of his priestly jubilee. In an effort promoted by the Paris Observatory, Fr. Denza joined an international project to catalogue and photograph the entire sky; this was the first major collaboration between observers on a global scale. Each participant was assigned the task of documenting an area of the sky spanning two celestial parallels with a double series of photographs. The Vatican Observatory was assigned the area between the +55 and +64 parallel. The photographic work included 1040 plates executed for cataloguing the stars and 540 for the heavens. For this task, two special lenses were newly commissioned, and eventually constructed by Paul Gautier. He built the mounting frame for the double refractor and the macromicrometer -both necessary instruments for all the cataloguing efforts. The new observatory was located in the Leonina Tower (now St. John’s Tower), where in 1891 a revolving 8 meter dome was built. It was equipped with two parallel refractors, a photographic telescope, and a collimator to adjust the line of sight of the telescope by producing parallel beams of rays. Here, the equatorial photographs were collected. Similarly, other observatories drew up instrumentation of the same specifications by mandate of the Parisian Charter of the Heavens to ensure homogeneity throughout the project. Pope Leone XIII, in his Ut Mysticam, confirmed on March 14, 1891 the solemn re-founding of the Vatican Observatory. When Fr. Denza passed away in 1894, Fr. Giuseppe Lais dedicated himself to the astronomical efforts for another 40 years, personally overseeing development operations and photographic printing efforts. After his death, Georg Hagen became the new observatory director, who’s noted studies of variable stars helped bring the cataloguing efforts to their conclusion. The instrumentation proved resultantly inadequate for the copious amount of cataloguing work, and so Hagen commissioned the Respold Company in Hamburg to construct two micrometers with identical plate dimensions to properly measure the position of every photographed star. This time, a female staff was hired; celestial measurements were taken by three nuns of the Sisters of Maria Bambina who worked from 1910 until 1921 upon completion of the task. The Charter of the Heavens, started by Fr. Lais with contributions from the Paris Academy of the Sciences, was finished in 1935, thanks to the new observatory in Castel Gandolfo. At the end of the war, the astrograph installed at the end of 1942 was put to use once again in the Villa Barberini, making it possible to complete some of the missing plates. Finally, fifty-five years after the onset of the project, all of the stars of the ten celestial zones were reproduced on 540 tables. One hundred copies of the entire work were printed, 90 of which were sent in homage to the principle observatories.


The official announcement was made in the general assembly of the International Astronomical Union in Moscow in 1958. Vatican astronomy still continues in its activities today, especially because of a 1980 agreement between the Vatican Observatory and the University of Arizona Steward Observatory. This pact allowed astronomers from the Vatican to use and access the telescopes at the Steward Observatory. Today, the new Vatican Observatory is home to a Vatican Advanced Technology Telescope, towering 3,200 meters above sea level on Mount Graham, northeast of Tucson. Its use in studying the Solar System includes researching asteroids, objects of the Kuiper belt, globular clusters in our galaxy, the formation of stars in nearby galaxies, and supernovas in distant galaxies -all thanks to financing from the Vatican Observatory Foundation.
The Direction of the Museum, together with the Vatican Observatory, now wish to allow the visitors to Castel Gandolfo to become participants in the activities of the Observatory though the centuries. For this reason, restoration of both telescopes of the Villa Barberini dome is imperative. The first comes from the Vatican’s Leonina Tower and has not been in use (since 1986) since the Charter of the Heavens project in 1890. With its incredible length of 3.43 meters and 33 cm diameter, the telescope is a visual testimony to the extensive astronomical history that has passed through the Vatican Observatory itself. The second is a Schmidt telescope from 1958, and was a personal gift to Pope Pio XII -he himself was passionate about astronomy. It is 3 meters long, has a diameter of 60-90 cm, and is equipped with a large camera that was used until the 1970s. The telescopes’ restoration is preparatory for that of an actual museum inside the dome. Visitors would enjoy not only the possibility to admire the astrolabes, armillary spheres, telescopes, spectrophotometers (for light measurement) and spectrochemical instruments, but also be able to understand and enter into the history of astronomy through modern multimedia systems.