GIOVANNI DOMENICO CASSINI
– or Jean-dominique Cassini, his official name after becoming a French citizen – was one of the most important astronomers of his time. He made significant discoveries in a period of transition that witnessed the final victory of Copernican astronomy and Newtonian physics over their Ptolemaic and Aristotelian counterparts.
His renowned meridian line within Bologna’s Basilica di San Petronio, one of the largest astronomical instruments in the world, proved the validity of the second law of Kepler. He made major discoveries about the Saturn system, and developed a theory of refraction that remained unparalleled for about 150 years.
Despite these remarkable results, the name of Cassini is surely less known than, for example, those of Galileo, Newton or Einstein. Fair enough, since his achievements, however important they are, must be compared with others that have a more fundamental and profound nature. Even conceding this essential difference, it is nonetheless most surprising to know that, to my knowledge, there exist no previous biographies of him.
Yet he has such historical importance that the CassiniHuygens mission, which recently completed 20 years exploring Saturn and its satellites, was named after him. This fact alone can justify the existence and the importance of Gabriella Bernardi’s book.
There is another thing that makes this work enriching. It reveals a distinctive and fundamental trait of the personality of this scientist. Less spectacular than his discoveries but possibly more significant was Cassini’s approach to the scientific endeavour, which included a well-defined planning of the research program and the establishment of longstanding and organised collaborations with a large team of fellow scientists working for a common goal.
In our ‘big science’ era this might be taken for granted, but in Cassini’s time it was an almost unknown concept. Scientists would rather follow their inconstant wishes and inspirations, generally in isolation. If we now consider the opposite as the normal way to proceed, it is because the French-italian astronomer introduced it. This kind of attitude made possible long and complex projects, like those that created the first modern map of France, and the first modern research institutions in the world, like the Paris Observatory. We tend to emphasise the discoveries of lone geniuses in shaping our world but the very fact we can consider Cassini’s approach so ‘modern’ and ‘natural’ means his gift to posterity has been no less significant in its influence.