What observation made by Galileo using a telescope decisively contradicted the geocentric view of Venus?

Answer

It exhibited a full set of phases, just like the Moon.

If Venus orbited Earth, it could never appear fully illuminated from our perspective; observing a full set of phases proved it must orbit the Sun, sometimes passing between Earth and the Sun.

What observation made by Galileo using a telescope decisively contradicted the geocentric view of Venus?

#Videos

Why Did The Geocentric Model Fail? - Physics Frontier - YouTube

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