Ole Rømer
Ole Rømer | |
|---|---|
Ole Rømer, portrait by Jacob Coning from c. 1700 | |
| Born | Ole Christensen Rømer 25 September 1644 |
| Died | 19 September 1710 (aged 65) |
| Nationality | Danish |
| Alma mater | University of Copenhagen |
| Known for | Rømer's determination of the speed of light Rømer scale Cycloid gear Light-time correction Altazimuth mount Meridian circle |
| Scientific career | |
| Fields | Astronomy |
| Signature | |
Ole Christensen Rømer (Danish: [ˈoːlə ˈʁœˀmɐ]; 25 September 1644 – 19 September 1710) was a Danish astronomer who, in 1676, first demonstrated that light travels at a finite speed. Rømer also invented the modern thermometer showing the temperature between two fixed points, namely the points at which water respectively boils and freezes.
Rømer made his discovery regarding the speed of light while working at the Royal Observatory in Paris and studying Jupiter's moon Io. He estimated that light takes about 11 minutes to travel from the Sun to Earth. Using today's knowledge of the Sun-Earth distance, this would amount to a speed of light of approximately 220,000 kilometers per second, compared to today's accepted value of just under 300,000 kilometers per second.
In scientific literature, alternative spellings such as "Roemer", "Römer", or "Romer" are common.