Giacomo Badoer[1][2] (c.1575 – c.1620) was a French-born diplomat, of Venetian parentage, and pupil of Galileo Galilei.
He later supported Galileo in 1607, in a priority dispute with Baldassarre Capra over the invention of a military compass.
[4] Badoer was one of the correspondents of Paolo Sarpi in Venice, who towards the end of 1608 was making enquiries about the invention in the Netherlands of the telescope.
Badoer wrote back in spring 1609 from Paris to Sarpi with news of the commercial telescopes then being sold; it is said that Galileo heard of the new product via this route, around July 1609.
[3] By upbringing Badoer was a Huguenot; he became a Catholic convert through the Jesuit Pierre Coton, at some point in the period 1599 to 1603, and by this connection became a diplomat in the service of Henry IV of France.