Telescopes from the Ground Up
Illustration representing various tools Galileo would have used, including a telescope, a globe, books, and writing materials.

Galileo’s Refractor

The politically powerful Catholic Church promoted the belief that the Earth was the center of the universe, along with the idea that the celestial bodies were perfect spheres, not covered with mountains and valleys.

Truth and consequences

Galileo was uncovering evidence for the Copernican theory. For instance, he saw that Venus had phases, like the Moon, which showed that the planet was moving around the Sun instead of the Earth. Also, Jupiter’s moons were clearly moving around Jupiter, not the Earth.

Galileo knew he had to be careful. If he said the Sun was at the center of the known universe, he would be disagreeing not only with an old belief, but also with stories in the Bible. Contradicting the Bible would be the same as saying the Church was wrong — and the Church at that time dealt harshly with those who challenged it.

Yet the more Galileo observed, the more convinced he became that the Copernican idea was correct. He felt so compelled to share his belief that he risked punishment by sharing his thoughts in an unrelated publication about sunspots.

Trials and tribulations

The Church, which had once supported Galileo, challenged his claim and ordered him to stop teaching his ideas. Galileo instead wrote a book about a fictional debate that strongly favored the Copernican theory.

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