Galileo Galileia

Galileo Galilei was an Italian natural philosopher, astronomer, and mathematician equally known for his contributions to developing new scientific results and for propagating the spirit of a new science based on experiment and observation. Galileo made fundamental contributions to the sciences of motion, astronomy, and strength of materials. Galileo studied speed and velocity, gravity and free fall, the principle of relativity, inertia, projectile motion and also worked in applied science and technology, describing the properties of pendulums and "hydrostatic balances", inventing the thermoscope and various military compasses. His formulation of (circular) inertia, the law of falling bodies, and parabolic trajectories marked the beginning of a fundamental change in the study of motion. His insistence that the book of nature was written in the language of mathematics changed natural philosophy from a verbal, qualitative account to a mathematical one in which experimentation became a recognized method for discovering the facts of nature. Galileo’s discoveries with the telescope revolutionized astronomy and paved the way for the acceptance of the Copernican heliocentric system. But the advocacy of the Coppernican system brought him to Inquisition by Church and led to his house arrest. Galileo on his own made increasingly powerful telescopes,and used thses telescopes for scientific observations of celestial objects. His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the observation of the four largest satellites of Jupiter, the observation of Saturn's rings, and the analysis of sunspots. He observed the Moon’s phases, showing that the Moon’s surface is not smooth, as had been thought, but is rough and uneven. He also found that the telescope showed many more stars than are visible with the naked eye. These discoveries were earthshaking, and Galileo quickly produced a little book, Sidereus Nuncius (The Sidereal Messenger), in which he described them. The book, Dialogo sopra i due massimi sistemi del mondo,tolemaico e copernicano (Dialogue Concerning the Two Chief World Systems, Ptolemaic & Copernican), was finished in 1630, and was published two years later after the Roman censures cleared it. In the Dialogue Galileo gathered together all the arguments (mostly based on his own telescopic discoveries) for the Copernican theory and against the traditional geocentric cosmology