Galileo Galilei (1564-1642) was an Italian astronomer, mathematician, and physicist who is widely regarded as the father of modern observational astronomy. He is known for his pioneering work in the fields of mechanics and optics, including his development of the telescope and his observations of the phases of Venus and the moons of Jupiter, which provided strong evidence for the heliocentric model of the solar system. Galileo's views on the nature of the universe and the relationship between science and religion were controversial and led to conflict with the Catholic Church. He was eventually placed under house arrest for the rest of his life.