Most of us carry the same story about Galileo. A scientist proves that the earth goes round the sun. The Church refuses to look through his telescope, puts him on trial, shows him the instruments of torture, and makes him take it back. As he rises from his knees he mutters, and yet it moves.
Almost every part of that story is in the popular histories. Very little of it is in the documents. The trial file survives, along with the letters on both sides and the dispatches the Tuscan ambassador sent home from Rome every few days. What they describe is a different and more interesting case: a man who was right about the earth, whose proof was wrong, and who was condemned in the end not for the moons or the sun but for a book.
What the telescope showed
On a January night in 1610, a professor of mathematics at Padua pointed a homemade telescope at Jupiter and saw three small stars beside it. He wrote down where they were and came back the next night to see whether they had moved. They had. Within weeks he had found four of them, moons circling another planet, and published them in The Starry Messenger. Within a year he had a court title in Florence and a philosopher's salary.
Between October and December 1610 he watched Venus go from a small round disc to a perfect half and begin to thin, like the moon. That finished the old system of Ptolemy, which put the earth at the centre with everything circling it: in Ptolemy's arrangement Venus could never show a full face.
But it did not prove that the earth moves. A third system, Tycho Brahe's, kept the earth still, sent the sun round it, and sent the planets round the sun. Seen from the earth, it predicts exactly what Copernicus predicts. Every single thing the telescope revealed fitted both. That is the problem the whole story turns on.
Read the rest of the story About eight minutes: 1616, the book, the trial, and the proof he never had.
This site is not connected with the Broadway production of Galileo.
