1609: Galileo

"Ladder to the Moon" (1958) by Georgia O'Keefe, at the Whitney Museum of American Art

Galileo Galilei, a 45-year old math professor at the University of Padua creates a telescope many times more powerful than any telescope ever built before.

In 1609, Galileo uses his telescope to observe the night sky.

Galileo’s telescope helps him discover how wrong many common beliefs about space are.

Many believe the Moon and sun have smooth surfaces which shows the absolute difference between the perfect and unchanging heavenly bodies and a corrupt Earth, whose surface is bumpy and irregular. But Galileo observes that the surface of the moon is not smooth at all. It is as mountainous, rough, and uneven as the Earth’s surface.

Galileo later discovers sunspots that show the Sun is not perfect either.

Galileo also discovers four moons revolving around Jupiter, which proves there is more than one center of motion in the Universe.

And he observes that Venus cycles through various phases, like the Moon does. This proves that Venus revolves around the Sun and also confirms the theories of Copernicus.

Some leaders of the Catholic Church ask Galileo about passages in the Bible like Psalm 104:5, which says “God set the Earth on its foundations; it can never be moved.”

They accuse Galileo of not believing in the Bible.

Galileo says people should read the Bible to learn about faith and morals, not science.

Pope Urban VIII makes Galileo promise to “abandon completely... the opinion that the sun stands still at the center of the world and the earth moves, and henceforth not to hold, teach, or defend it in any way whatever, either orally or in writing.”

“… in discussions of [Nature] we ought to begin not from the authority of scriptural passages but from sense-experiences and necessary demonstrations.”
--Letter from Galileo to the Grand Duchess Christina of Tuscany, 1615