Galileo Galilei (1564-1642) was an Italian physicist, mathematician, and astronomer who played a major role in the Scientific Revolution. Some of his key achievements included improving the telescope, making various scientific discoveries such as observing the moons of Jupiter and sunspots, and proposing that the Earth revolves around the sun rather than vice versa. However, his heliocentric view of the solar system was controversial and condemned by the Catholic Church, who felt it contradicted scripture.