Western Civilization I / Unit 17 WC1 1624 short lesson, about 20 seconds
Brahe's Data, Kepler's Ellipses
Captions available
The idea
Tycho Brahe spent twenty years observing to refute heliocentrism and left the data that disproved him. Johannes Kepler, his assistant, used it to prove the sun central and, by convention, that planets move in ellipses, sensing a force from the sun he called magnetism.
In practice
Imperial mathematician to Rudolf II.
Where people slip
Kepler's ellipses are unwitnessed; the anchor says only sun-centered.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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