Simplify the following text for a Grade 10 native English-speaking person.
Original: 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 .