The Operating System of the Solar System

Johannes Kepler was born on December 27, 1571, in Weil der Stadt, in what is now Germany. His father was a mercenary who disappeared when Kepler was young. His mother was later accused of witchcraft. Kepler himself was sickly, near-sighted, and socially awkward. He was also one of the most important scientists who ever lived.

Kepler's three laws of planetary motion, published between 1609 and 1619, describe how planets orbit the Sun. The first law states that orbits are ellipses, not circles. The second describes how planets move faster when closer to the Sun. The third relates orbital period to distance. These laws replaced centuries of complicated epicycles with elegant mathematics. Copernicus had shown that planets orbit the Sun. Kepler showed how.

He arrived at these laws through years of painstaking calculation using Tycho Brahe's astronomical observations -- the most precise available before telescopes. Kepler inherited Brahe's data after serving as his assistant. The relationship was contentious. Brahe guarded his data jealously. When Brahe died in 1601, Kepler gained access to the complete dataset and spent years fitting it to mathematical models.

diagram illustrating kepler's laws of planetary motion. source: wikimedia commons

Kepler's laws became the foundation for Newton's theory of gravity. Newton showed that Kepler's ellipses were a consequence of the inverse-square law of gravitation. Without Kepler's empirical laws, Newton's theoretical framework would have had nothing to explain.

Kepler died in 1630, impoverished and largely unrecognized. His grave was destroyed during the Thirty Years' War. But his laws are still used today to calculate satellite orbits and plan interplanetary missions. The operating system of the solar system runs on Kepler's code.