History of astronomy and the Phases of Venus

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Discussion Overview

The discussion revolves around the historical understanding of the heliocentric model of the cosmos and its implications for the phases of Venus, particularly focusing on when these phases were first recognized as evidence for heliocentrism. The conversation touches on the contributions of figures such as Galileo and Nicholas of Cusa, exploring the evolution of astronomical thought from ancient to early modern times.

Discussion Character

  • Historical
  • Debate/contested

Main Points Raised

  • One participant questions when it was first realized that the heliocentric model should show the phases of Venus, suggesting that this understanding may have been absent until Galileo's observations in the 17th century.
  • Another participant asserts that prior to Galileo's telescope observations, planets were perceived merely as points of light, which raises the question of how such points could exhibit phases.
  • A participant reiterates the idea that Galileo was the first to recognize the phases of Venus as a significant argument for heliocentrism.
  • There is a mention of Nicholas of Cusa, with a participant questioning whether he considered planets as bodies with living beings, and expressing skepticism about the rationale for distinguishing planets from stars.
  • Another participant acknowledges the speculative nature of Cusa's views on the universe being infinite and admits to not having read his original texts, while referencing biographical sources about him.

Areas of Agreement / Disagreement

Participants express differing views on the historical timeline of the understanding of the phases of Venus and the contributions of various figures. There is no consensus on when the implications of heliocentrism regarding Venus were fully recognized.

Contextual Notes

Limitations include the lack of definitive documentation regarding Nicholas of Cusa's views and the speculative nature of interpretations surrounding his ideas. The discussion also reflects varying degrees of certainty about historical perspectives on astronomy.

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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