Galileo's vertebra
On August 2, 1823 the University of Padua received as a gift the fifth lumbar vertebra of Galileo Galilei, offered by the Vicenza doctor Domenico Thiene.
The history of this relic is long and complex. After the scientist's death on 8 January 1642 in Arcetri, his body was temporarily placed in the Basilica of Santa Croce in Florence. About a century later, on March 12, 1737, it was exhumed to be transferred to the mausoleum dedicated to him, also inside the same basilica.
For the occasion, Grand Duke Gian Gastone de' Medici set up a commission in charge of the transfer, composed of the doctors Antonio Cocchi and Giovanni Targioni Tozzetti, the prelate Giovanni Vincenzo Capponi, the erudite Anton Francesco Gori and the notary Giovanni Cammillo di Pasquale di Piero Piombanti. Faced with Galileo's skeleton, the members of the commission could not resist the temptation to take some "relics": Capponi took the index finger and a thumb of his right hand, Gori the index finger of his left, Tozzetti probably a tooth, while Cocchi took possession of the fifth lumbar vertebra.
After several changes of hands, the vertebra arrived in 1820 to Domenico Thiene, who three years later donated it to the University of Padua, during the rectorship of Antonio Meneghelli.
Anthropological analyses of the vertebra show no signs of serious pathologies: X-rays and CT scans reveal only slight arthritic irregularities and minimal osteophytosis. Recent medical studies suggest that Galileo may have died of reactive arthritis, probably triggered by an infection with Chlamydia pneumoniae, then complicated by uveitis that led to bilateral blindness. The absence of obvious lesions on the vertebra does not contradict this hypothesis.
A 3D survey with very high density of points and micrometric resolution, carried out with a structured light scanner of the Department of Cultural Heritage of the University of Padua, has made it possible to reconstruct with millimeter precision the morphological and morphometric characteristics of Galileo's vertebra.
The vertebra was acquired from multiple angles thanks to the use of a rotating platter synchronized via software with the scanner. In this way it was possible to obtain a complete and continuous relief, overcoming the difficulties related to the complex morphology of the find, characterized by undercuts, shadowy areas and translucent details, such as the seal.
The 3D model obtained represents a concentrate of morphological and morphometric information essential for the physical reproduction of the vertebra: in fact, it constitutes the skeleton and the basic structure on which the prototype was developed. After careful optimization, the model data was converted into instructions for the machine path for 3D printing.
To minimize any margin of error, a second copy was made, used for color tests and to verify the rendering compared to the original. This phase was also made possible thanks to the photographic campaign carried out during the survey, which made it possible to faithfully reproduce both the tonality of the bone fragment and the complex interweaving of the ligature of the original vertebra.