Astronomer. Born in Aarhus, he studied at the Copenhagen University, but from 1672 to 1681 he lived and worked at the Paris Observatory. While in Paris he acted as a teacher to the crown prince of France as well as projecting the supply of water for the fountains at Versailles. He won international fame when in 1676, during his observations of Jupiter's satellites, he discovered the "procrastination of light," i.e. the speed of light. In 1680 he demonstrated a machine showing the orbits of the planets and a machine for calculating the Moon's eclipses to the Académie des Sciences in Paris and to King Louis XIV. Both machines are still preserved in Paris. King Christian V of Denmark adquired a set in 1682, and in 1685 similar sets were presented to the King of Siam and the Emperor of China. Back in Denmark in 1681 Ole Rømer became the king's trusted adviser in all technical matters. He rationalised a number of existing systems and introduced a uniform system of weights and measures as well as introducing the Gregorian calendar.
Bio by: Erik Skytte