Galileo proved Ptolemy wrong.

Qu. Who did Galileo prove wrong?
https://www.quora.com/Who-did-Galileo-prove-wrong/answer/Hans-Georg-Lundahl-1

Hans-Georg Lundahl

none/ apprx Masters in Latin (language) & Greek (language), Lund University

6 years ago

Galileo proved Ptolemy wrong.

So, by the way, did Tycho Brahe.

Btw, in the process involving a discussion of the evidence, under St. Robert Bellarmine, no one was defending Ptolemy. St. Robert was defending Tycho Brahe.

Walter Hehl

May 25

Galilei did not prove the heliocentric world model nor refute Ptolemy. He just looked through the telescope and observed mountains on the moon and phases of Venus. This suggested that the planets and the moon are bodies and not only points of light. The discovery of the moons of Jupiter showed that there are bodies not circling around the earth (nor the sun). But this could also mean that the epicycles are real ….

The proof that the earth circles around the sun was given 1728 by William Bradley, the direct proof that the earth rotates was made by Léon Foucault 1851.

Hans-Georg Lundahl

June 1st

“This suggested that the planets and the moon are bodies and not only points of light.”

That was known to Ptolemy.

“The discovery of the moons of Jupiter showed that there are bodies not circling around the earth (nor the sun). But this could also mean that the epicycles are real”

In Ptolemy, an epicycle is around a void epicentre, it doesn’t have a body as an epicentre.

So, on this item, he proved Ptolemy wrong.

No proofs were ever given that Earth either orbits the Sun or rotates, both 1728 and 1851 allow other interpretations.

Walter Hehl

Tue 2.VI.2026

How should Ptolemy know that the planets are physical bodies like the earth?

The position of the center of epicycles depends on the eccentricity of the true ellipse: if it is zero. the centers are identical.

A

Fri 5.VI.2026

Hans-Georg Lundahl

How shouldn’t he know it?

They move against the zodiac, and therefore cannot be dots, even luminous ones, on one solid surface.

I’m sorry about the second, but sounds like gobbledygook to me, perhaps bc I’m tired.

B

Fri 5.VI.2026

Hans-Georg Lundahl

You are obviously free to communicate as you see fit, and to answer as you see fit.

However, I get the feeling you are not communicating straight. I am not an AI. I am also not a demon. I am a man, bullied on more than one side, and can find this exhausting.

“the eccentricity of the true ellipse: if it is zero. the centers are identical.”

You mean, if it is zero, the foci are identical and the ellipse is a circle, right?

An ellipse and an epicycle are not the same thing.

“The position of the center of epicycles”

Was never the issue. In a solidly Ptolemaic tradition, an epicycle is not filled with a body or with an apparent body (if you want to insist on having found someone in doubt on whether planets were bodies or light spots). Also, the moving centre of an epicycle itself moves in a circle, not in an epicycle. Since Jupiter has an epicycle, the four moons or satellites of Jupiter disprove this.

So, Galileo did disprove Ptolemy.

Now, why did you try to obfuscate that instead of arguing on this probably obvious disagreement between us? No proofs were ever given that Earth either orbits the Sun or rotates, both 1728 and 1851 allow other interpretations.

If it’s making a case for “du bist ein Laie, du hast kein Recht darüber zu argumentieren” I’d answer: “ich bin kein Saupreißn” and I don’t care about who a sow Prussian considers as having a right or not a right to an opinion or argument.