Ole Rømer

Portrait of Ole Rømer. The original can be found at the Astronomical Observatory, Niels Bohr Institute for Astrophysics, Physics, and Geophysics, Copenhagen University.

Ole Rømer is known in particular for his discovery of `the hesitation of light', that is to say that the speed of light is finite, as well as being an instrument builder and very careful observer. Here I give just a brief overview of his life and career :

• Born September 25 1644 in Aarhus. Graduated from the Aarhus Cathedral school in 1662.
• 1662 - 1671: Studies at Copenhagen University with Rasmus Bartholin.
• 1672 - 1681: Works at the Paris observatory. Determined the speed of light by observing Jupiter's moons ; a treatise on this result was published in 1676.
• 1681: Returns to Copenhagen to become professor of astronomy. Developed equipment for the accurate determination of stellar positions, among which the meridian circle in ca. 1704. His practical duties were among other things the standardization of weights and measures, the reform of the calendar in 1700, and securing the public water supply of Copenhagen.
• 1705: Chief of police in Copenhagen.
• Deceased September 19, 1710.