Why did the early rabbis of Late Antiquity believe that the sun revolves around the earth?
On the surface, the Sages wanted to uphold the belief that the earth is still the center of God’s universe. However, in all honesty, one cannot blame the ancient rabbis for thinking that way; the majority of them were unacquainted with the science of the Greeks, many of whom (like Aristotle) believed that the earth revolves around the sun. One would be hard pressed to find a modern rabbi of the last five centuries who would argue otherwise, yet, in modern times there is one famous rabbi who unabashedly believes in the science of Ptolemy over Copernicus–the late Lubavitcher Rebbe. Here is an extraordinary letter the Rebbe wrote (dated: September 16, 1968):
I am in receipt of your letter of September 10th, in which you touch upon the question of whether the sun revolves around the earth or vice versa, in view of the fact that you heard from a college student that the truth is that the earth revolves around the sun. It greatly surprises me that, according to your letter, the student declared that science has resolved that the earth revolves around the sun. The surprising thing is that a person making such a declaration would be about one half a century behind the times insofar as the position of modern science is concerned. This belief is completely refuted by the theory of Relativity, which has been accepted by all scientists as the basis for all the branches of science.
One of the basic elements of this theory is that when two bodies in space are in motion relative to one another (actually the theory was initiated on the basis of the movements of stars, planets, the earth, etc.), science declares with absolute certainty that from the scientific point of view both possibilities are equally valid, namely that the earth revolves around the sun, or the sun revolves around the earth.
Cited from Herman Branover, Joseph Ginsburg, and Menachem Mendel Schneersohn (trans. Arnie Gotfryd) Mind over Matter: The Lubavitcher Rebbe on Science, Technology and Medicine (Jerusalem: Shamir 2003), 75-77.