Here's a problem to solve: In the 1500s, Nicolaus Copernicus proposed a new theory on the heliocentric structure of the solar system. Which of these statements best describes this new theory?

Among the 4 following options, which is the correct answer?

- A: Earth is at the center of the solar system.
 
- B: There are eight planets in the solar system.
 
- C: The Sun is at the center of the solar system.
 
- D: Moons have circular orbits in the solar system.
 