Galileo Galilei (1564-1642) was an Italian astronomer, physicist, and mathematician. He is considered one of the most important figures in the scientific revolution of the 16th and 17th centuries. Galileo was born in Pisa, Italy, and was the eldest of six children. He attended the University of Pisa where he studied medicine and mathematics but left without completing his degree. In 1609, Galileo heard about the invention of the telescope in the Netherlands and built his own. He used it to observe the night sky and made several important discoveries, including the moons of Jupiter and the phases of Venus, which supported the heliocentric theory of the solar system proposed by Copernicus. Galileo's support of the heliocentric theory brought him into conflict with the Catholic Church, which held that the Earth was the center of the universe. In 1632, Galileo published his book, "Dialogue Concerning the Two Chief World Systems," which argued for the heliocentric view. This l...