text: Galileo Galilei ( ; 15 February 1564 â `` 8 January 1642 ) , commonly known as Galileo , was an Italian physicist , mathematician , astronomer and philosopher who played a major role in the Scientific Revolution .
simplified: Galileo Galilei ( 15 February 1564 â `` 8 January 1642 ) was an Italian astronomer , and a famous thinker .