Galileo Galilei was born February 15, 1564. He was a natural Italian philosopher, astronomer, and mathematician. In his middle teen years he went to school at Vallombrosa, and then in 1581 he got enrolled at the University of Pisa. He started going to school at Pisa to study medicine, but then got sidetracked by mathematics. In 1583 he discovered something very important, he found out how to describe the ways that rule the motion of pendulums. His most important scientific contributions were in the field of physics. He invented a telescope that helped him discover the lunar surfaces on the planets, the moons of Jupiter, the rings of Saturn, the phases of Venus, and a lot of more stuff including the sunspots. In 1585 he left the university