The Celestial Sphere was (and remains) an useful way in which to represent the Universe and, in fact, it is still the way astronomers choose to model the observable sky. [The Celestial Sphere also gives us a natural way in which to picture the daily motions (diurnal motions) of the objects that we observe in the heavens. However, in order to explain the complex behavior of the planets, contrived scenarios needed to be postulated. This state-of-affairs contributed to the assigment of god-like status to things like the planets].
Hmmm, but wait a minute. Physically the model does not make sense as we know that the Earth is not stationary, it is not in the center of the Universe, and the stars (and other celestial objects) are not attached to the surface of a large sphere (i.e., stellar positions) and they do not orbit around the Earth. So,
How is the Celestial Sphere model able to provide such an accurate representation of the Universe (and sky)?
To answer this question we must think about the kinds of effects produced by the motions of the Earth, the Sun, and the stars and how the motions manifest themselves.
Consequences of the Motions of Celestial Bodies
Later, we will return to the issue of how you can convince someone that the Earth moves and is not stationary.