Google Doodle celebrates Johannes Kepler


Today’s Google Doodle celebrates the 442nd birthday of the German mathematician and astronomer Johannes Kepler.
Johannes Kepler was born on 27 December 1571 in the free imperial city Weil der Stadt near Stuttgart. e became an associate of Prince Hans Ulrich von Eggenberg, when he was teaching in Graz, Austria. And became an assistant to astronomer Tyro Brahe and later the imperial mathematician to Emperor Rudolf II and his successors Matthias and Ferdinand II.
Unlike Galileo Galilei he was not interested in public approval of his findings.
“I much prefer the criticism of a single intelligent man to the thoughtless approval of the masses.”

Johannes Kepler was the first astronomer to explain planetary motion. While studying the orbit of Mars he discovered that the planets don’t move in circles, but in ellipses, a completely unthinkable approach until then. He concluded that all planets move in ellipses, which is Kepler’s first law of planetary motion. He is best known for his eponymous laws of planetary motion. In 1609 “De astronomia nova – About the new astronomy” was published.

Kepler’s laws are:
The orbit of every planet is an ellipse with the Sun at one of the two foci.
A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.
The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.