Galileo (1564-1642) was a founder of Western science and the first to look at the night sky through a telescope. What he saw brought him face to face against the Catholic Church. The Church condemned and silenced him but they could not silence his ideas.
He was one of the first to use experiments to do science, where ideas are put to the test to see if they are really true. He found holes in Aristotle’s physics.
The telescope made things far away seem nearer. Galileo did not invent the telescope but he was the first to point it at the night sky. It was like going up into the sky yourself.
He was the first to see the mountains on the moon, the stars in the Milky Way, the spots on the sun, the moons of Jupiter and the the waxing of Venus.
This all came as a shock.
In the universities they taught the theories of Ptolemy and Aristotle: the sun and all the planets circled round the earth and the heavens were perfect and eternal. The Church never declared Ptolemy and Aristotle to be doctrine, but the theories of both had stood for hundreds of years and seemed like eternal truths.
But as Galileo found, they were not. His experiments in physics and what he saw through his telescope cast serious doubts upon both. He found that Copernicus was right after all: the planets did not orbit the earth but the sun.
Until Galileo, the theory of Copernicus was merely interesting, but now he had proof that it was true.
With the facts on his side he wrote a book about Copernicus. In it three friends argued about whether Ptolemy or Copernicus was right. One was for Copernicus one for Ptolemy and the other was making up his mind.
Galileo framed it as a dispute because the Church had told him not to teach or write about the theory of Copernicus as if it were true. But it was hardly even-handed: the defender of Ptolemy was called Simplicius.
The wrath of the Church came down on him. He was surprised: the pope was his friend and a lover of science. Galileo was a pious, sincere Christian who only wanted to guide the Church to new truths. He felt that his enemies in the universities were pulling strings.
Galileo was called before the Inquisition. He was questioned, made to confess that Copernicus was wrong and then he was silenced. He was to go to prison, but later it was agreed he could live at home but not come and go as he pleased.
He retired to his country house near Florence where he lived the rest of his days with his daughter. He never said another word about Copernicus, but there he wrote “The Two New Sciences”, laying the foundation of the new physics that would destroy Aristotle and be developed by Newton.
He died in 1642. That Christmas Newton was born.