Multiple choice general knowledge Knock knock! Who's there? Nicolaus Copernicus. Nicolaus Copernicus, who are you? Painter Creator of Silly Putty Inventor of the steam locomotive Astronomer Reveal answer Fill a bubble to check yourself D Correct answer Explanation Nicolaus Copernicus was a Renaissance astronomer who formulated the heliocentric model of the universe, placing the Sun rather than Earth at the center. He is one of history's most famous astronomers.