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Kepler finds the planets' orbits
The circle abandoned after two thousand years
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Brahe's measurements were the most accurate before the telescope, and the discrepancy Kepler could not explain away amounted to eight arcminutes. That he refused to round it away is the very example of what scientific honesty means. His laws gave Newton the empirical ground for gravitation two generations later.
For children
Everyone had assumed heavenly bodies must move in perfect circles. Kepler worked on Tycho Brahe's observations of Mars for years and found the orbit is an ellipse. It was hard to accept — for him too.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org