Wednesday, February 9, 2022


 One of the stronger proofs of heliocentrism that Galileo found was the phases of Venus.  This came to mind this morning while looking at Venus through the living room windows.  Venus is currently in crescent phase but Galileo also observed it in gibbous phase.  And this means?

The only way for Venus to go gibbous is if it is on the far side of the Sun.

Why does this matter?

Four out of Five Americans Know Earth Revolves Around Sun
Probing a more universal measure of knowledge, Gallup also asked the following basic science question, which has been used to indicate the level of public knowledge in two European countries in recent years: "As far as you know, does the earth revolve around the sun or does the sun revolve around the earth?" In the new poll, about four out of five Americans (79%) correctly respond that the earth revolves around the sun, while 18% say it is the other way around. These results are comparable to those found in Germany when a similar question was asked there in 1996; in response to that poll, 74% of Germans gave the correct answer, while 16% thought the sun revolved around the earth, and 10% said they didn't know. When the question was asked in Great Britain that same year, 67% answered correctly, 19% answered incorrectly, and 14% didn't know.

So Americans are not more science ignorant than Germans or Britons.  That's a relief. 


  1. Galileo did observer the Venus phases, but that did not prove heliocentrism. A leading theory of the day was Tycho's, where Venus revolves around the Sun, and the Sun revolves around the Earth. That model is consistent with the Venus phases.

    1. That's why I wrote stronger. The website from whence came that illustration mentioned that third model of which I knew nothing.