Question

You hear two students explaining how modern astronomers model the apparent motion of the sky:

a) The first student says, "The celestial sphere assumes that all the stars are the same distance from Earth and that the sphere rotates around a motionless Earth."
b) The second student says, "That's correct, except that it does not assume the Earth is motionless.
c) The Earth or the sphere can rotate with no difference in the appearance of the sky from the Earth."
With which student do you agree?

Answer 1

The second student is correct in stating that the Earth's rotation accounts for the apparent movement of the sky, as per the Copernican model, which is supported by physical laws, including the demonstration by Foucault's pendulum.

Step-by-step explanation:

I agree with the second student's explanation regarding how modern astronomers model the apparent motion of the sky. The celestial sphere concept is a useful tool for explaining the night sky's appearance, despite its simplification that the stars are equidistant from Earth. However, contrary to the Ptolemaic view that presupposes a geocentric model with Earth at the center, it's acknowledged that either the Earth rotates on its axis, or we can visualize a rotating sphere with no difference in the observed sky.

The Copernican model, which places the Sun at the center of the solar system, suggests that the apparent motion of the sky can be explained by Earth's rotation. This heliocentric model is supported by laws of physics, including Newton's universal law of gravitation. The evidence of Earth's rotation was famously demonstrated by Foucault's pendulum, which showed that Earth rotates beneath a swinging pendulum, altering its plane of oscillation. Astronomy has confirmed that Earth's rotation, not the motion of a celestial sphere, explains the diurnal motion of the sky.