Galileo's observation of the phases of Venus supported Ptolemy's epicycles?

Answer 1

Galileo's telescopic observations of the 4 large moons of Jupiter and the phases of Venus helped support the heliocentric model of the solar system developed by Copernicus. Copernicus predicted that all phases would be visible since the orbit of Venus around the Sun would cause its illuminated hemisphere to face the Earth when it was on the opposite side of the Sun and to face away from the Earth when it was on the Earth-side of the Sun. In contrast, the geocentric model of Ptolemy predicted that only crescent and new phases would be seen since Venus was thought to remain between the Sun and Earth during its orbit around the Earth. Galileo's observations of the phases of Venus proved that it orbited the Sun and lent support to (but did not prove) the heliocentric model.

Answer 2

Yes, of course. Venus showed phases, which indicated it revolved around the sun, and Jupiter had moons, which showed that not everything revolved around the Earth.

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Additional information: the phases of Venus are also explained by the geocentric system, which allows for Venus to pass between the Sun and the Earth - the condition for causing the crescent phase to be seen from Earth.

So Venus's phases neither support nor contradict the heliocentric model. However Jupiter's moons were the first objects discovered that definitely did not orbit round the Sun. So this gave an indirect boost to the heliocentric concept by showing it isn't impossible.

Answer 3

Galileo's observation of the phases of Venus did not support Ptolemy's Ptolemy's epicycles. In fact, Galileo showed that Venus could not possibly be positioned between the Sun and Earth.

Answer 4

He did suppport Copernicus's view of the solar system because he helped explained the backwards motion of the planets