I History of astronomy and the Phases of Venus

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The discussion centers on the realization of the heliocentric model's implications for the phases of Venus, primarily attributed to Galileo's observations in the 17th century. Prior to Galileo, planets were perceived merely as points of light, and the concept of them exhibiting phases was not considered. Some participants mention Nicholas of Cusa, who lived before Galileo, speculating on the nature of planets, but there is uncertainty regarding his specific views on planetary phases. The conversation emphasizes that Galileo's findings were pivotal in supporting the heliocentric theory. Overall, the phases of Venus were not recognized as a consequence of heliocentrism until Galileo's telescope observations.
windy miller
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Does anyone know when it was first realized that a heliocentric model of the cosmos should show the phases of Venus in the way Galileo saw them in the 17th century.?Was it known in the time of Aristarchus or did people only realize this was a consequence of helicoentrism later on, perhaps only in the 17th century Ad or ...?
Many thanks
 
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I could be wrong, but I don't think anyone thought about it until Galileo pointed his telescope at the skies and discovered the phases of Venus. Before then the planets were just points of light. How could a point source show phases? It was Galileo that first realized that the phases of Venus were a powerful argument in favor of the heliocentric model.
 
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phyzguy said:
I could be wrong, but I don't think anyone thought about it until Galileo pointed his telescope at the skies and discovered the phases of Venus. Before then the planets were just points of light. How could a point source show phases? It was Galileo that first realized that the phases of Venus were a powerful argument in favor of the heliocentric model.
Didn't Nicholas of Cusa (who was alive about 200 years before Galileo saw Venus through his telescope ) think of planets as bodies with living beings on them?
 
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windy miller said:
Didn't Nicholas of Cusa (who was alive about 200 years before Galileo saw Venus through his telescope ) think of planets as bodies with living beings on them?
Maybe. If so, I'd like to see the documentation. Why would you single out the planets from the stars? They look the same except that the planets move.
 
Well he also thought the universe was infinite, I'm not sure there was observational evidence for that either but people like to speculate. As for documentation, I have read many sources that refer to his views but I can't claim to have read his original texts. But here is an example of a brief biography, there are many others : https://www.catholicscientists.org/catholic-scientists-of-the-past/nicholas-of-cusa

Source https://www.physicsforums.com/threads/history-of-astronomy-and-the-phases-of-venus.1009674/
 
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