Galileo Galilei was born on February 15, 1564, in Pisa, Italy, and died on January 8, 1642, in Arcetri, Italy. Galileo was an Italian astronomer mathematician, and physicist. His work contributed significantly to the development of the scientific method, especially in the sense that the Book of Nature was written in the language of mathematics. He also made great strides in observational astronomy, allowing the Copernican heliocentric theory to be accepted.