Simplify the following text for a Grade 9 native English-speaking person.
Original: Nicolaus Copernicus ( ; ; ; in his youth , Niclas Koppernigk ; ; 19 February 1473 â `` 24 May 1543 ) was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology , which displaced the Earth from the center of the universe .
Simplified: Nicolaus Copernicus ( 19 February 1473 â `` 24 May 1543 ) was an astronomer .