La Specola (Bologna)
La Specola is the historical name of Italy's first university observatory in Bologna . In 1712 it was added to the Palazzo Poggi as an observation tower , where the newly founded Academy Istituto delle Scienze also had its seat. Today the historical observatory serves as a museum for astronomical and physical instruments.
prehistory
When Copernicus began his studies at the University of Bologna in 1497 , it did not have its own observatory. Although Copernicus mentioned in his later main work De revolutionibus .. two joint observations of the moon with the experienced astronomer Dominicus Maria Novara , the location of the measurements was probably only a terrace. It was the same when Giovanni Domenico Cassini accepted the call to Bologna in 1650. He set up his famous 66.7 m long meridian , which still exists today, in the Basilica of San Petronio for his solar observations to determine the time and the exact inclination of the ecliptic . It was not until 1665 that he was able to determine the orbits of Jupiter's moons with a long-focal telescope . a. Christiaan Huygens made it possible to determine the speed of light.
In 1669 Cassini was lured to Paris to head the new Royal Observatory. As a result, astronomy in Bologna lost its importance - until the initiative of a patron, Count Luigi Ferdinando Marsili (1658–1730). He made his instruments available to interested young researchers and had an observatory built at the palace, the Specola Marsiliana , where observations were carried out until 1709.
Foundation and first successes
When Marsili wanted to relocate his station after various quarrels, the Senate of Bologna offered him the construction of an observatory tower with a laboratory, library and the assumption of some professors' salaries. 1712 was with the participation of Pope Clement XI. signed the contract to establish the scientific academy Istituto delle Scienze di Bologna at Palazzo Poggi. The tower was started by the architect Giuseppe Torri in 1713, but was not completed until 1726 because of his death. He entrusted the specialist planning as well as the later management to Eustachio Manfredi (1674–1739), who had already looked after the Specola Marsiliana as an observer .
In terms of instruments, the observatory was well equipped from the start. As was customary at the time, the main instrument was a large wall quadrant . With it, the geographical latitude of the observation station could be determined to a previously unachieved 0.8 ". Manfredi also tried to measure the parallaxes of two bright stars to prove Copernicus' world system , but they were much smaller (ie their distances much greater) than expected. In the course of this, however, he was able to confirm the 20 " annual aberration of some stars found by James Bradley . His successor Zanotti, in turn, successfully carried out the measurements for his star catalog from 1750 with English precision instruments by Jonathan Sisson , especially the large wall quadrant .
literature
- Volker Witt: The historical observatory "La Specola" in Bologna. In: Stars and Space. Vol. 44, No. 1, 2005, ISSN 0039-1263 , pp. 76-81.
Coordinates: 44 ° 29 '48.03 " N , 11 ° 21' 9.18" E