It's pretty amazing how accurate it is while they assumed geocentricity. Maybe it's Einstein who said it best:

The struggle, so violent in the early days of science, between the views of Ptolemy and Copernicus would then be quite meaningless. Either CS could be used with equal justification. The two sentences, 'the sun is at rest and the earth moves,' or 'the sun moves and the earth is at rest,' would simply mean two different conventions concerning two different CS.
-Einstein