# On distances

## Question:

The distances Tycho gives are:

- BA = 97,500
- AC = 101,400

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:

Click here for the answer.