Galileo's Phases of Venus Date: 01.01.1610 Galileo Galilei's observations that Venus appeared in phases - similar to those of Earth's Moon - in our sky was evidence that Venus orbited the Sun and contributed to the downfall of the centuries-old belief that the Sun and planets revolved around Earth.
His observations of the phases of Venus and the moons of Jupiter proved that the planets move around the Sun.
Image Credit: Istituto di Linguistica Computazionale