Galilei

Galilei (Galileo Galilei; 15 February 1564 – 8 January 1642) was an Italian astronomer, physicist, engineer, and central figure of the Scientific Revolution. Born in Pisa, he studied medicine at the University of Pisa but turned to mathematics and natural philosophy, later holding professorships at Pisa and Padua before serving as court scientist for the Medici family of Florence.

In 1609 he learned of a device that could magnify distant objects and used telescopes to observe celestial bodies, reporting discoveries such as the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto), the rough surface of the Moon, the phases of Venus, and sunspots. These observations provided empirical support for the Copernican model of the solar system and challenged Aristotelian cosmology. He published The Starry Messenger (1609) and Letters on Sunspots (1613), among other works, which helped establish observational astronomy as a science.

In 1632 he defended heliocentrism in Dialogue Concerning the Two Chief World Systems. The subsequent Inquisition trial in 1633 led to a conviction for heresy, forced recantation, and house arrest for life; his Dialogue was banned and his writings restricted. He continued to write during confinement, producing Discourses and Mathematical Demonstrations Relating to Two New Sciences (1638), which advanced the study of motion and matter.

Galilei's work helped inaugurate modern science by emphasizing observation, experimentation, and mathematical description. His legacy extends through the scientific method, modern physics and astronomy, and the continued study of his observations. The surname Galilei remains associated with his contributions and with the broader legacy of the scientific revolution.