Another one from the Galileo Heliocentrism series.
GALILEO PROVED THE HELIOCENTRIC MODEL THROUGH HIS DISCOVERY OF THE PHASES OF VENUS
The Phases of Venus are the different variations of lighting seen on the planet’s surface similar to the moon’s phases. They result from the planet’s orbit around the Sun being inside the Earth’s orbit. The first known observations of the planetary phases of Venus were done by Galileo with his telescope in late 1610. The discovery of Venus’s phases was monumental as it essentially ruled out Ptolemy’s geocentric model which placed the earth at the center of the universe; and was compatible only with the heliocentric model of Nicolaus Copernicus with sun at the center of the solar system.