Which US astronaut became the first man to hit a golf ball on the moon?

Which of the following statements about the celestial sphere is not true?

a. The celestial sphere does not exist physically.
b. When we look in the sky, the stars all appear to be located on the celestial sphere.
c. The Earth is placed at the center of the celestial sphere.
d. The "celestial sphere" is another name for our universe.