The observation of what phenomenon on Venus provided definitive proof supporting the Copernican arrangement?

Answer

A complete cycle of phases (crescent, gibbous, nearly full)

Seeing Venus display phases similar to the Moon, including gibbous and full stages, could only happen if Venus orbited the Sun, not the Earth.

The observation of what phenomenon on Venus provided definitive proof supporting the Copernican arrangement?

#Videos

Galileo's Revolutionary Observation - YouTube

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