Final answer:
Galileo discovered that Venus exhibited phases similar to the Moon, which could not be reconciled with the geocentric model but supported the heliocentric solar system. Additionally, his observation of moons orbiting Jupiter showed that not all celestial bodies revolved around Earth. These discoveries challenged the prevailing geocentric view of the universe.
Step-by-step explanation:
Galileo Galilei discovered through his observations with the telescope that Venus exhibited a full set of phases like the Moon. These observations of the phases of Venus provided critical evidence for the Copernican theory of a heliocentric solar system. The phases could not be accounted for by Ptolemy’s geocentric model, which posited Venus orbited Earth. Instead, the changing appearances of Venus as seen from Earth aligned with predictions of the heliocentric model, where Venus orbits the Sun, causing different portions of its sunlit side to be visible from Earth at varying times. Galileo’s findings, therefore, cast significant doubt on the prevailing geocentric view and supported the revolutionary notion that not all celestial bodies revolve around Earth.
Moreover, Galileo’s discovery of the moons orbiting around Jupiter further discredited geocentrism by showing that there were centers of motion apart from the Earth, such as other planets that had their own satellites. These astronomical discoveries challenged the dominant philosophical and religious ideologies of the time, which held Earth at the center of the universe, leading to conflict with Church authorities.