Galileo
The phases of Venus are well supported by the heliocentric system, but they are also supported very well by the previous geocentric system. All you need for Venus to have phases is that Venus should pass between Earth and Sun. That happens in both the heliocentric system and the geocentric system.
Galileo believed the heliocentric view of the universe was correct based on his observations through a telescope, such as the phases of Venus and the moons of Jupiter. These observations provided evidence supporting the idea that the Earth revolved around the Sun, challenging the geocentric view supported by the Catholic Church at the time.
Galileo Galilei was put on trial by the Inquisition for advocating the heliocentric model of the universe, which contradicted the geocentric views of the Catholic Church at the time. His writings that supported the findings of Copernicus were considered heretical by the Church, leading to his trial and subsequent conviction.
Scientists such as Nicolaus Copernicus and Galileo Galilei developed ideas that contradicted Ptolemy's geocentric model of the universe. Copernicus proposed a heliocentric model with the sun at the center, while Galileo's observations through a telescope supported this idea, leading to the eventual acceptance of the heliocentric model.
That idea is called heliocentric.
Galileo's observations with his telescope supported the concept of heliocentricism. He noted that the satellites of Jupiter and Venus, based on their range of phases, did not match geocentricism supported by Ptolemy. He noted that based on these findings, that the Heliocentric theory was correct.
heliocentric theory
The phases of Venus are well supported by the heliocentric system, but they are also supported very well by the previous geocentric system. All you need for Venus to have phases is that Venus should pass between Earth and Sun. That happens in both the heliocentric system and the geocentric system.
Galileo
Galileo
The phases of Venus are well supported by the heliocentric system, but they are also supported very well by the previous geocentric system. All you need for Venus to have phases is that Venus should pass between Earth and Sun. That happens in both the heliocentric system and the geocentric system.
Copernicus
The two main proponents in the early days were Nicolas Copernicus and Galileo.
By looking into space with the telescope.
The original idea (at least, the earliest of which we're aware) that the Earth circled the Sun was proposed by Aristarchus of Samos, a Greek astronomer and mathematician. But the Aristotle's idea that the Sun circled the Earth was more "obviously apparent" and became accepted as fact. The reintroduction of the heliocentric theory by Copernicus, supported by more accurate celestial observations, came almost 1700 years later.
Copernicus proposed a heliocentric model with the sun at the center of the solar system, while Galileo supported this idea with observational evidence through his use of the telescope. Galileo's observations also challenged the geocentric model supported by the Catholic Church at the time.
Galileo believed the heliocentric view of the universe was correct based on his observations through a telescope, such as the phases of Venus and the moons of Jupiter. These observations provided evidence supporting the idea that the Earth revolved around the Sun, challenging the geocentric view supported by the Catholic Church at the time.