Galileo was a famous scientist born in 1564, and he made many great contributions to the world of astronomy. Some of his famous discoveries were the phases of Venus, the four largest moons of Jupiter, and sunspots. However, when he spoke his mind that the earth rotated around the sun, already said by Copernicus, he was protested against. When he published his beliefs in a book, in 1616, he was tried and put in house arrest for the rest of his life.
For more information about Galileo, go to: http://en.wikipedia.org/wiki/Galileo_Galilei
For more about Copernicus, go to: http://en.wikipedia.org/wiki/Nicolaus_Copernicus