On April 14, 1611 in Rome there was a great celebration for Galileo Galilei. He was 47 years old and had already been to Rome, but this time he was different. He was now a celebrity. Prince Federico Cesi, who in 1603 had founded the Accademia dei Lincei with the aim of gathering the scientists of the time into a circle, had organized everything to allow Galileo to demonstrate how a new instrument he had built worked. The event lasted a whole day and took place on the Janiculum Hill, at the highest point, where a monsignor had built a holiday residence, the Casino Malvasia (which was later destroyed in the 19th century, today the American Academy stands there) . The new instrument was mounted there, in an open space in front of the Casino from where you can enjoy a spectacular view of Rome. The instrument made it possible to see objects at a great distance: at first it was aimed at the basilica of San Giovanni in Laterano where it was possible to clearly read the inscription that Sixtus V had placed there in the first year of his pontificate; then even on the Tuscolane Hills, twenty-five kilometers away, where Prince Altemps had a villa from which it was possible to distinguish even the smallest windows. But the real show was at night, when through the instrument, the participants in the banquet could see the satellites of Jupiter and realize that Saturn was not a star (all things that Galileo already knew from the year before, that is, since he had perfected the invention of a Dutchman).
In short, that instrument was a marvel and would have changed the world, the way we perceive it. Galileo had called him small cell, in Latin; some called it “cannon or glasses”, in Italian, hence the expression “canocchiale”. But it was on that occasion that Federico Cesi (or according to others the Greek scholar Giovanni Demisiani), invented the name it still bears: telescope, a union of two Greek words that mean “to see far away”. Curiously but not too much, in 1625 another exponent of the Accademia dei Lincei, Giovanni Faber, applied the same technique to invent the word microscope.