Kepler's laws
Planets move in ellipses, and celestial physics becomes ordinary physics.
- When
- —
- Duration
- 10 years
- Known to
- ± 1 year
- Era
- Early Modern, Holocene
Working from Tycho Brahe's exceptionally precise observations, Kepler spends years trying to fit Mars to a circle, fails by eight minutes of arc, and refuses to ignore the discrepancy. The result, published from 1609, is that orbits are ellipses with the Sun at a focus, that planets sweep equal areas in equal times, and that period relates to distance by a fixed law. Two thousand years of assumed circular perfection ends because of an error he would not round away.