Abstract
Landgrave Wilhelm IV established in 1560 the first permanent astronomical observatory in Europe. When he met the young Tycho Brahe in 1575 he recognized the genius and recommended him warmly to the Danish king Frederik II. Wilhelm and Tycho must share the credit for renewing astronomy with very accurate observations of positions of stars by new instrumentation and new methods. Tycho's observations of planets during 20 years enabled Johannes Kepler to derive the laws of planetary motion. These laws set Isaac Newton in a position to publish the laws of physical motion and universal gravitation in 1687 - the basis for the technical revolution.
