E pluribus unum: The first international scientific collaboration

In June 1761 and 1769, while European powers were fighting in the struggles for colonial hegemony, more than 250 astronomers and scholars from different nations gave life to the first international scientific enterprise: the observation of Venus transit, an extremely rare event that, if watched simultaneously from very distant locations, would have made it possible to calculate the Earth-Sun distance. A masterful example of how collaboration and sharing are two essential elements for science progress, but also of how knowledge and studying the history of a scientific concept allows us to fully grasp its current meaning.