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Science1609

Kepler’s Laws of Planetary Motion

Also called: Kepler’s laws, Astronomia nova

In his New Astronomy of 1609 Kepler showed that planets move in elliptical orbits with the Sun at one focus, giving heliocentrism precise mathematical support.

Kepler’s model of the planetary orbits in his Mysterium Cosmographicum, explained by nesting the five Platonic solids
Kepler’s model of the planetary orbits in his Mysterium Cosmographicum, explained by nesting the five Platonic solids

Johannes Kepler · Public domain · Source

As court mathematician to the Holy Roman Emperor Rudolf II in Prague, Kepler wrestled with the precise observations of Mars left by the Danish astronomer Tycho Brahe. In his New Astronomy of 1609 he showed that planets move not in circles but in ellipses (the first law) and that the line joining a planet to the Sun sweeps out equal areas in equal times (the second law). In 1619 he added the third law: the square of a planet’s period is proportional to the cube of its orbit’s semi-major axis.

Abandoning the age-old belief in perfect circular motion, these laws were later explained by Newton’s law of universal gravitation.

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States at the time
Holy Roman Empire

People

  • Johannes Kepler1571 – 1630

    author · German astronomer who, working from Tycho Brahe’s observations, found the laws of planetary motion, showing that planets move in ellipses

Before and after

Earlier
1555 Peace of Augsburg
Later
1618 Thirty Years’ War

Themes that include this event

  • Scientific Revolution, Enlightenment and the English Revolutions1543 – 1796

    The Scientific Revolution from Copernicus to Newton, parliamentary government in England won through the Puritan and Glorious Revolutions, and the Enlightenment that sought to remake society by reason — the groundwork of the civic revolutions and the Industrial Revolution