The Specola Vaticana: Astronomy at the Vatican

Organizations, People and Strategies in Astronomy 2 (OPSA 2), 217-230 Ed. A. Heck, © 2013 Venngeist. THE SPECOLA VATICANA: ASTRONOMY AT THE VATICAN GUY CONSOLMAGNO AND CHRISTOPHER CORBALLY Specola Vaticana V-00120, Vatican City State [email protected] [email protected] Abstract. The Vatican is an independent nation, with its own national astronomical observatory, the Specola Vaticana (Vatican Observatory). As- tronomy has been supported at the Vatican since the 1582 reform of the calendar; the present-day Observatory has been in operation since 1891. The work of the observatory is divided between two sites, one in the pa- pal summer gardens south of Rome, Italy, and the other affiliated with the Steward Observatory at the University of Arizona, in Tucson, Arizona, USA. Research undertaken by current staff members ranges from cosmology and the study of galactic evolution to meteoritics and meteors. Given the stable funding provided by the Vatican, the Observatory has specialized in long-term mapping and cataloguing projects that would be difficult to mount under a traditional three-year funding cycle. These have included participation in the Carte du Ciel photographic map of the sky; the at- lases of spectra produced by its Spectrochemical Laboratory; surveys of star clusters and peculiar stars; and the cataloguing of meteorite physical properties. 1. Astronomy in the Holy See Before 1891 To the Christian church, the study of creation has long been supported as an act of worshipping the Creator. Astronomy was one of the seven subjects that made up the curriculum of the medieval universities, which were themselves founded by the Church. Understanding the motions of objects seen in the sky had philosophical and theological implications in the cosmology of those times; the physical universe was thought to parallel the metaphysical universe. 218 GUY CONSOLMAGNO AND CHRISTOPHER CORBALLY However, the first specific hiring of astronomers by the Holy See itself had a much more practical purpose: to reform the calendar. Following the instructions of the Council of Trent, Pope Gregory XIII (1502-1585) as- sembled a group of scholars in 1580 to help determine how to correct the roughly one-day-per-century shortfall of the ancient Roman calendar, and how to determine the date of Easter in a way that would be practical for a Christendom that was now spreading from East Asia to the Americas. Along with the resulting Gregorian reform, promulgated in 1582, the Do- minican mathematician Ignazio Danti (1536-1586) installed a meridian line in the top room of the newly-constructed Tower of the Winds (so named because it was decorated with depictions of the four winds on its walls, and contained an elaborate mechanical wind vane), which could be used to demonstrate the ten-day error in the unreformed calendar. The Jesuit priest Christopher Clavius (1537-1612) was one of the mathe- maticians involved in the reform. At the Pope’s request, he wrote a lengthy explanation of the reasons for the reform, published in 1602; but even after that work was completed he and other Jesuits at the Roman College continued to do astronomical research. They were among the first to confirm Galileo’s telescopic observations, though they remained skeptical about the Copernican system. Eventually, however, Galileo angered many of the Jesuits by claiming priority over the German Jesuit Christof Scheiner (1575-1650) on the dis- covery of sunspots, and belittling the (essentially accurate) observations of comets by the Roman Jesuit Orazio Grassi (1583-1654). Ten years later, Galileo was brought to his infamous trial; historians still argue over the reasons for that trial, which may have had as much to do with politics as with philosophical differences (the trial occurred at the height of the Thirty Years War), but it is clear that this enmity with the Jesuits cost him their friendship when it would have been most helpful. Astronomy remained a rich field of study for the Jesuits at the Roman College even during and after the Galileo trial, however. In 1616, Nicholas Zucchi (1586-1670) built what was perhaps the first reflecting telescope; Gilles-Franois de Gottignies (1630-1689) observed the comets of 1664, 1665, and 1668; and Athanasius Kircher (1601-1680) made detailed telescopic drawings of Jupiter and Saturn. [In addition, see Heilbron (2001) for a description of the use of cathedrals as astronomical observatories during this time; and Graney (2012) on the work of the Jesuits Riccioli and Grimaldi during this era.] In the following century, Roger Boscovich (1711-1787) convinced the Vatican to lift its formal opposition to the Copernican system; in addition, he studied transits, cometary orbits, and the optics of telescopes. In the latter years of the 18th century, small Pontifical observatories were set up in © 2013 Venngeist. ASTRONOMY AT THE VATICAN 219 Figure 1. The image of Secchi’s telescope on the roof of Saint Ignatius Church, prepared by Giovanni della Longa circa 1870. This image is reprinted in L’Astronomia in Roma nel Pontificato di Pio IX, Memoria del P. A. Secchi, Tipografia della Pace, Roma (1877). the Tower of the Winds in the Vatican, and at the Jesuits’ Roman College. These two observatories continued to operate in parallel into the 19th century. At the Roman College, Giuseppe Calandrelli (1749-1827), Andrea Conti (1777-1840), and Giacomo Ricchebach (1776-1841) produced eight volumes of Opuscoli Astronomici (Astronomical Tracts), detailing their research on the sun, planets, comets, and stellar occultations. Other Je- suit astronomers in Rome, including Etienne Dumouchel (1773-1840) and Francesco de Vico (1805-1848), were the first to recover Comet Halley in 1835; De Vico also observed the Saturnian satellites Mimas and Enceladus, determining their orbits. Meanwhile, from the towers of the Vatican itself, Feliciano Scarpellini (1762-1840), Ignazio Calandrelli (1792-1866; nephew of Giuseppe Caladrelli), and Lorenzo Respighi (1824-1889) observed the solar chromosphere and made astrometric observations. But by far the most notable astronomer in Rome during this century was Angelo Secchi (1818-1878), a Jesuit at the Roman College. His reputation © 2013 Venngeist. 220 GUY CONSOLMAGNO AND CHRISTOPHER CORBALLY went far beyond Italy; he was honored by both the Emperor of Brazil and Napoleon III of France (who named him an Officer of the Legion of Honour). He published more than 700 scientific papers on topics as diverse as terres- trial magnetism and solar physics, and established the connection between sunspots and solar flares. He was also a pioneer in spectroscopy, the first to systematically classify stars by their spectral features. His spectral work included the first identification of carbon in stars, comets, meteors, and nebulae. And his work on solar physics was so fundamental that even today it has been honored in the naming of the Sun Earth Connection Coronal and Heleospheric Investigation (SECCHI) instrument package on NASA’s Stereo spacecraft. So great was his reputation that when the anti-clerical Italian government confiscated the Roman College following the capture of Rome from the Holy See in 1870, Secchi was still allowed to continue his work even though he refused to take an oath to the new government. Secchi died in 1878, however, leading to a hiatus in Vatican sponsored astronomy until Pope Leo XIII formally re-established an observatory in 1891. The present day Vatican Observatory dates itself from this moment. [For more details on the early history of astronomy and the Vatican, see Maffeo (2001) and Consolmagno (2006).] 2. Three Epochs of the Specola In Pope Leo XIII’s Motu Propio, a personal decree that re-established the Specola Vaticana (“specola” is an antique Italian word meaning observatory), the Pope explained the apologetic need for supporting a scientific in- stitution. “This plan,” he wrote, “is simply that everyone might see clearly that the Church and her Pastors are not opposed to true and solid sci- ence, whether human or divine, but that they embrace it, encourage it, and promote it with the fullest possible dedication.” The original Specola Vaticana was located once more in the Tower of the Winds, with additional telescopes located on the ancient walls of the Vatican. Its original work embraced both astronomy and meteorology, and it went through a number of directors in its early years before the arrival of Johann Hagen (1847-1930) in 1906. He was the first Jesuit in the reformed observatory, which included at that time a combination of clerical and lay staff. Hagen made the decision to concentrate the work of the observatory purely on astronomy; his own research centered on cataloging nebulae, espe- cially dark nebulae (which he correctly deduced were masses of interstellar matter), and variable stars. A more curious interest of Hagen’s was a series of experiments to demonstrate the rotation of the Earth. Though no one doubted by this time that the Earth was spinning, its actual motion had only been shown by Fou- © 2013 Venngeist. ASTRONOMY AT THE VATICAN 221 Figure 2. Giuseppe Lais at the Carte du Ciel telescope, circa 1900. From Maffeo (2001). cault’s Pendulum in 1851. Hagen devised a series of clever experiments to demonstrate the action of the Coriolis force arising from motions on the Earth’s spinning surface. These including the very careful observation of a falling weight (via an Atwood machine) in a stairwell at the Vatican; the mapping of the apsidal rotation of a pendulum; and the motion of a long suspended beam on which heavy weights traveled in a north-south direction. Thus arose the irony that the Vatican, infamous for having opposed Galileo and his championing of the Copernicus system, three centuries later supported some of the first laboratory experiments that confirmed the Coper- nican hypothesis of the Earth’s spin.

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