ASTRONOMICAL OBSERVATORIES. —
I. HISTORICAL NOTES
Disregarding the very ancient Chinese observatories, about which there is very uncertain information, it is known that in the classical world the first observatories appeared in Mesopotamia, perhaps around the 10th century B.C., and consisted of high pyramidal towers with multiple levels (the ziggurats of the Babylonians), some remains of which have been found at Horsabad, near Nineveh. As is well known, the Chaldean priests (whom G. V. Schiaparelli rightly called the great fathers of astronomy) were diligent students of the stars and celestial movements; indeed, they had succeeded in devising a practical method (the so-called Saros cycle) for the approximate prediction of solar and lunar eclipses.From Chaldea, astronomy passed into Egypt and then into Greece; and, after the Macedonian conquest, the center of studies shifted from Athens to Alexandria in Egypt, flourishing under the Ptolemies who founded there the famous Museum, with a very rich library and a celebrated observatory illustrated by Eratosthenes (276–196 B.C.), one of the greatest astronomers of antiquity. The Alexandrian school of astronomy came to a close, so to speak, with Claudius Ptolemy (2nd century A.D.), who in his Almagest summarized the knowledge of past generations.
With him, the ancient era of astronomy ends and the medieval astronomical era begins. In the Middle Ages, astronomy was greatly cultivated by the Arabs, who translated the Almagest into their language (later translated into Latin by Gerard of Cremona in 1180) and made many observations of planets and comets with their astrolabes and triquetrums. A precious Arab astrolabe, built in Valencia in 1175 by Sa'd Ibrahim, is preserved in the Astronomical Museum of the Observatory of Rome on Monte Mario.
Among the Arab observatories, particular mention should be made of that of the astronomer al-Battani (Albatensis) in Mesopotamia (10th century), and that of Ulugh Beg in Samarkand (Turkestan); the works of al-Battani, found in the Library of the Escorial, were recently published by A. Nallino in the Arabic text with a Latin translation.
With the advent of the modern age, true astronomical observatories also began to appear in Europe. Among the earliest, prior to the discovery of the telescope, are the one in Kassel (Germany), erected in 1561 by William IV, Landgrave of Hesse, and the famous observatory of Tycho Brahe on the island of Hven (Baltic Sea), where the great Danish astronomer carried out those methodical and precise observations of the positions of the planet Mars, which later led Kepler to discover the famous three laws on the heliocentric motion of the planets. However, a true flourishing of astronomy took place only after the invention of the telescope (1609) and after Galileo’s first discoveries regarding sunspots, the mountains of the Moon, the phases of Venus, the satellites of Jupiter, the Milky Way, etc.
The following century saw the foundation of the great European observatories: Paris (1667), Greenwich (1675), Berlin (1705), St. Petersburg (1725), Vienna (1735), etc.
As regards Italy in particular, mention should be made of the Observatory of S. Maria in Vallicella in Rome, founded by the Pope who made observations of the comet of 1680: these observations were honored by being cited by Newton himself. This was the first Italian observatory of which there is record, since earlier observations by Clavius, Scheiner, and E. Divini had been made from terraces with portable telescopes; it was followed by the observatory of the University of Bologna, founded in 1714. A few years later, the Jesuits, who resided in the Palazzo di Brera in Milan, where they taught philosophy and theology, founded the Milanese observatory (1760), entrusting its direction to the illustrious mathematician and astronomer Fr. Ruggero Boscovich. Shortly afterward (1766), by decree of the Venetian Senate, the Observatory of Padua was erected in the tower of Ezzelino; then Fr. De Caesaris founded in Rome (1780), near S. Maria Maggiore, the Caetani Observatory, later transferred to the Campidoglio, while a few years later (1787) Abbot Giuseppe Calandrelli founded the Observatory of the Collegio Romano in a small tower he had built on that building and still visible from the square of the same name.
After the storm of the French Revolution had passed, Abbot Giuseppe Piazzi (who, a few years earlier, had founded the Observatory of Palermo on the tower of S. Ninfa and greatly enhanced it with the discovery of the first asteroid, Ceres Ferdinandea) was invited by Ferdinand I to complete and direct the Observatory of Naples, whose construction had just begun at Capodimonte (1812). Later (1823), Pope Leo XII reorganized studies with the brief Quod divina sapientia and established the foundation of an observatory on the great eastern tower of the Palazzo del Campidoglio in Rome; this foundation was entrusted to Abbot Feliciano Scarpellini, who transferred the equipment from the old Caetani observatory, which he had directed, to the Campidoglio and added new scientific instruments. Almost simultaneously, G. Plana founded the Observatory of Turin on one of the towers of Palazzo Madama; D. De Vecchi established the Observatory of Florence in the Palazzo del Museo delle Scienze, etc. The end of the 19th century saw the establishment (1888) of the Vatican Observatory, then located on the Leonine Tower within the Vatican walls.
II. MODERN ASTRONOMICAL OBSERVATORIES
With the advent of the 20th century, astronomical observatories completely abandoned the old towers where they had always been housed and instead required possession of a plot of land (preferably on a hill) where, in separate pavilions, they could place the instruments intended for positional measurements of planets and stars (transit instruments, meridian circles, etc.). Indeed, the high precision now demanded in positional measurements requires that these instruments have maximum stability and therefore be placed directly on the ground on very solid foundations. Moreover, the ever-increasing use of celestial photography, especially in astrophysics for the study of nebulae and stellar spectra, often necessitates taking such photographs under special conditions, for example, in the mountains. On the other hand, the photographic plates thus obtained must then be measured and studied with great care; and experience has shown that for every hour spent photographing the sky, fifty or seventy hours of desk work are required for examining the plates. However, there is no need to perform this lengthy examination in the same place where the photographs were taken; moreover, large observatories often have rich libraries, provide timekeeping services, and are also seats of advanced courses for students, so it would be impractical to locate them far from cities and major universities. The problem has therefore been solved by equipping modern observatories with suitable “branch observatories.”Thus, for example, as regards Italy, the Astronomical Observatory of Rome abandoned its ancient urban sites and moved to the summit of Monte Mario on the first meridian of Italy, placing its positional instruments in separate pavilions within the park, and has recently established a branch station on the Gran Sasso d’Italia at an altitude of 2,300 meters above sea level. Similarly, the Observatory of Bologna has set up a branch at Loiano in the Apennines; that of Padua at Asiago at an altitude of 1,000 meters; that of Milan at Merate, etc. Likewise, the Observatory of Turin was moved by its director, G. Boccardi, from the towers of Palazzo Madama to a suitable park near Pino Torinese; the Observatory of Florence, under the care of G. B. Donati, moved from the old Palazzo del Museo to the hill of Arcetri near the city. And most recently, the Vatican Observatory, under the direction of the Jesuit Fr. J. Stein, left the old Leonine Tower for the pontifical park of Castel Gandolfo.
But the great advances in astronomy have led to further specialization of observatories. At present, it is inconceivable that a single observatory could cover all fields of astronomy, just as no institute today could profitably engage in all branches of medicine. Modern observatories therefore tend to be divided into proper astronomical observatories, whose tasks primarily concern positional astronomy or classical astronomy; astrophysical observatories, which deal mainly with the physical constitution of celestial bodies; solar observatories, which study the Sun; and astronomical laboratories, which are particularly devoted to calculations and the examination of photographic plates obtained at other observatories.
Naturally, purely geodetic (in Italy, the observatory at Carloforte, which studies movements of the Earth’s pole), meteorological, or seismic observatories—which observe meteorological phenomena, earthquakes, microseisms, etc.—are excluded from this classification. It should be noted that this division is neither absolute nor rigid but merely indicative. Thus, for example, there are observatories that are both astronomical and solar, or astrophysical and solar, or astronomical and meteorological, or astronomical and seismic, and so on.
At present, the United States undoubtedly constitutes the nation where astronomy is most advanced, both in the number and in the high potential of the observatories at its disposal. It will suffice to mention those of Mount Palomar, Mount Wilson, Mount Hamilton, and the Lowell Observatory, among others.
### III. ASTRONOMICAL INSTRUMENTS
The principal instruments of observatories are: the high-precision clock, the meridian telescope, the equatorial telescope (visual or photographic), the astrograph, the reflector, and the solar tower. The first group pertains more specifically to astronomical observatories, while the last group pertains to astrophysical and solar observatories.
Clocks are generally placed in underground rooms or in temperature-controlled chambers, often beneath pneumatic bells maintaining constant pressure. Meridian telescopes, housed in separate pavilions within the observatory grounds, are of modest size and can move only in the plane of the meridian. They are used to determine the precise moment when a star crosses the meridian and its altitude at that moment above the horizon. From these observations, the astronomer derives the celestial coordinates of the star under examination (right ascension and declination), the correction of the clock, and the longitude and latitude of the observatory. Equatorial telescopes are large telescopes (the largest, belonging to the Yerkes Observatory, has a lens over one meter in diameter) housed under rotating domes. They are used for studying double stars, variable stars, determining stellar parallaxes, examining the physical characteristics of planets, and so on. For this purpose, they are equipped with a special equatorial mounting and driven by an electric motor that allows them to automatically follow a star in its apparent motion from rising to setting. Astrographs are photographic equatorial telescopes of modest size but equipped with a lens system that enables them to photograph a wide region of the sky. They are particularly useful for discovering and determining the positions of minor planets and comets. Reflectors are large equatorial telescopes in which the objective lens is replaced by a parabolic (or spherical, in the modern Schmidt type) mirror. Since the mirror concentrates all light rays at the same focus regardless of their wavelength, and since it can be constructed in very large sizes (the one at Mount Palomar has a diameter of 5 meters), the reflector may be considered the principal instrument of astrophysics for studying stellar spectra and photographing faint nebulae, among other tasks. The solar tower is a tall tower (the one at Mount Wilson is about 50 meters high; the one at Monte Mario in Rome, the largest in Italy, is about 35 meters) that supports, within its interior, a vertical telescope of length equal to the tower’s height. At the top of the tower, beneath a rotating dome, is a system of movable mirrors (a coelostat) that directs the solar rays onto the objective lens of the telescope.
The astronomer is stationed in a room at ground level of the tower, where a large solar image is formed, which can be studied or photographed conveniently. In the basement, there is another apparatus (a spectroheliograph) that permits spectroscopic study of individual regions of the Sun, as well as photography using only the light emitted by certain chemical elements, such as hydrogen and calcium. This allows the distribution and movements of calcium and hydrogen clouds in the Sun’s upper layers (the chromosphere) to be identified.
For brevity, mention will be made here of auxiliary astronomical instruments (micrometers, photometers, chronographs, spectrographs, plate-measuring devices, calculating machines, etc.), as well as meteorological and seismic instruments (barometers, thermometers, hygrometers, anemometers, seismometers, etc.). It should also be noted that some observatories possess rich libraries and, at times (such as, for example, the Observatory of Rome), even an astronomical museum. — See pl. XXVII.
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### IV. SCIENTIFIC OBSERVATORIES IN MISSIONS
Scientific observatories in missions attract the esteem and goodwill of peoples toward the Church and also serve to combat widespread popular superstitions. The most famous observatory in the history of missions is the one erected in the early 17th century at the court of Peking by the Jesuits, among whom Father Johann Adam Schall von Bell, a German, distinguished himself by constructing the observatory itself, and Father Ferdinand Verbiest, a Fleming, served as its first European director. The scientific work of these Fathers at the court indirectly yielded great advantages to the missions (see CHINA, III. Evangelization). The suppression of the Society of Jesus at the end of the 18th century brought an end to the scientific work of the Jesuits at Peking, and it was never resumed.
In the second half of the 19th century, however, other scientific observatories arose. In Manila, the Jesuits founded a meteorological station in 1865, which, under the direction of Father Federico Faura y Prat, a Spaniard, quickly developed into the Manila Observatory. Although the Fathers’ primary concern was the prediction of typhoons, they soon added geognostic, seismological, and astronomical sections. The observatory was completely destroyed in February 1945 during the evacuation of the city by the Japanese army. Father Faura earned great renown for inventing an instrument for predicting typhoons.
The Zi-ka-wei Observatory near Shanghai, which in a certain sense marks the revival of the ancient imperial observatory of China, was founded by French Jesuits in 1873. Fr. Luigi Fr. (known as the “Father of Typhoons”), and his successor, Fr. Ernesto Grèzi, rendered great service to the economic and commercial development of that Chinese coast through their increasingly accurate and reliable typhoon forecasts. From a scientific standpoint, however, no less important was the work of the other sections established at the Zi-ka-wei Observatory and at its branch in Zo-sè. The Observatory published for meteorology a *Bulletin de prévision de temps* (daily) and for astronomy the *Annales de l'Observatoire de Zoè*. Among the most recent and important publications by Fr. E. Gherzi, one may note: *La météorologie de la Chine* (published by the Pontifical Academy of Sciences [Rome 1939]) and *Climatological atlas of Asia* (Shanghai 1944). In 1950, the buildings were occupied by the communist government of China.
Of lesser importance is the Observatory of Ambohidempona on the island of Madagascar, founded in 1889 by French Jesuits. For some time, in collaboration with government institutions, the Fathers engaged in the study of cyclones, which are fairly rare in that region. But the most important work of that observatory consists of geomagnetic research, carried out by the current director, Fr. Charles Poisson. It also has sections for astronomy, seismology, and meteorology. It also had an important geodesy section.
In 1907 the French Jesuit Fr. Bonaventura Berloty founded the Observatory of Ksara in Lebanon, which is part of Saint Joseph University in Beirut. From 1921 until 1944 the official direction of the State Meteorological Service was combined with that of the observatory. In addition to the meteorological section, it includes astronomical, geomagnetic, and seismological sections. The climatological study of Lebanon constitutes its most important work. Until 1940 the Observatory published the *Annales de l'Observatoire de Ksara*, and until 1945 the *Climatologie aéronautique*. Now it publishes monthly: *Bulletin mensuel de climatologie* and *Bulletin sismologique prévisoire*.
Fr. Edward Pigot, an Irish Jesuit, was in 1908 the founder of a seismological station, which developed into the Astronomical and Seismological Observatory of Riverview, near Sydney in Australia. The current director is Fr. Daniel O'Connel. The main work of that observatory consists in photographic photometry, especially of variable stars.
Since in mission countries governments always wish to have their own observatories, it is foreseen that observatories in the missions will gradually lose their public importance and will rather be transformed into scientific research institutes affiliated with universities or colleges run by missionaries. Alfonso Smetsers