Galileo Galilei (Pisa, 1564 / Arcetri, 1642) was an Italian astronomer, philosopher, engineer, mathematician and physicist, closely related to the Scientific Revolution. An eminent man of the Renaissance, he showed interest in almost all the sciences and arts (music, literature, painting). He was the first astronomer to direct a telescope to the sky, making multiple discoveries in this area: he discovered that the Moon had mountains and «seas» instead of being the smooth and perfect sphere that was considered, the satellites of Jupiter (which showed that there were objects other than Earth or Sun around which other objects revolved), that Saturn had two bumps on its sides and sunspots (which also showed that the Sun was not a smooth and perfect sphere either). He also did studies on the motion of objects (formulating the first law of motion) and on light. His support for the heliocentric theory of Copernicus in his book Dialogo sopra i due massimi sistemi del mondo (1632) led to a process by the Inquisition.
