Galileo Galilei

Galileo improved the Dutch telescope, achieving 20x magnification. He used it to observe the Moon's craters, Jupiter's moons, and the phases of Venus. These observations provided evidence for the Copernican heliocentric model and challenged Aristotelian cosmology.

Galileo discovered four moons orbiting Jupiter (Io, Europa, Ganymede, Callisto). This observation demonstrated that not all celestial bodies orbit Earth, contradicting geocentric models. He published the findings in Sidereus Nuncius.

The Catholic Church declared heliocentrism heretical and ordered Galileo to abandon his support for Copernican theory. He was warned not to teach or defend heliocentrism. This marked the beginning of his conflict with Church authorities.

Galileo published a dialogue comparing Ptolemaic and Copernican systems, arguing for heliocentrism. The book was seen as violating the 1616 injunction. It led to his trial and condemnation by the Inquisition.

The Roman Inquisition tried Galileo for heresy, forcing him to recant his heliocentric views. He was sentenced to house arrest for life, where he continued scientific work. This event symbolized the conflict between science and religious authority.