Galileo Galilei was an Italian physicist, mathematician, and astronomer born in 1564 in Pisa, Italy. He made many important scientific discoveries that helped establish modern science. Some key achievements included improving the telescope and using it to study the sky, discovering that the speed of falling objects is independent of their mass, and providing evidence that supported the Copernican model of the solar system. Galileo faced opposition from the Catholic Church for his scientific views and was put under house arrest for the final years of his life until his death in 1642.