Johannes Kepler (1571 - 1630) founded modern astronomy together with Nikolaus Kopernikus (1473 - 1543) and Galileo Galilei (1564 - 1642) and initiated the transition to modern scientific thinking. Kepler's Astronomia Nova (1609) and Harmonice Mundi (1619) were crucial contributions to the foundation on which generations of researchers have built since then. His scientific work is based on the rediscovery of the thoughts and knowledge of antiquity during the Renaissance in Europe.

At the beginning of the 17th century there was a revolution in people's thinking and worldview that could not have been bigger. After almost 2000 years since Aristotle, there was increasing evidence that the earth is not in the center of the cosmos, but rather moves as a planet around the sun.

Linz Portrait of Johannes Kepler (1620)

During this time full of upheavals and tensions, Kepler's life was also shaped by the consequences of the Reformation and the Counter-Reformation. At a time when dogmatically canonized "knowledge", which if questioned critically, had become almost life-threatening, Kepler was determined to serve the truth and to put aside his own career advantages. This determination is also reflected in his scientific work.

On the basis of Tycho Brahe's observations, he fundamentally changed the theory of planetary motions and paved the way for astronomy to the physics of celestial motions. For the first time in the history of astronomy, a unified orbit theory was worked out that is equally valid for all planets, moons, comets and other celestial objects, which is also valid for the spaceships and satellites sent into space by humans today. The successes in space travel and the exploration of the universe through satellites are made possible because of Kepler's groundbreaking discoveries.
The space telescope of the Kepler mission (NASA image)

This is illustrated by the example of the current American space project of the NASA Kepler mission, "A Search for Habitable Planets". In March 2009, exactly 400 years after Kepler's famous Astronomia Nova, NASA put a telescope into solar orbit to search for extrasolar planets in a specific area of ​​the Milky Way, in the Swan constellation. That NASA chose the name “Kepler” for the project is not simply to remember one of the greatest astronomers, instead it is to recognize Kepler's discovery of the laws of planetary motion, the laws on which the NASA project is directly based.

As if he had foreseen it, Kepler wrote in 1610 as an imperial mathematician at the court of Rudolf II in Prague in his dissertation Cum Nuncio Sidereo to Galileo Galilei:

... Create ships and sails that are suitable for the air of heaven. Then there will also be people who will not shrink back from the barren expanse of space.

Here you will find an overview of the most important dates from Kepler's life.