On distances
Question:
The distances Tycho gives are:
but Kepler says that "in the correction which is to follow, BA turns out a little longer and AC a little shorter; they are not equal, however." So the correct lengths are closer to each other than Tycho says, meaning that the eccentricity of the Earth-Sun orbit is smaller than Tycho indicates.
Can you think of what would cause Tycho to make this error? Look again at the aside if you want a hint.
Answer:
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