Ole Rømer

Ole Rømer was a Danish astronomer best known for his pioneering work in measuring the speed of light. In 1676, he observed that the orbits of Jupiter's moon Io changed depending on the Earth's distance from Jupiter, leading him to deduce that light travels at a finite speed. His calculations estimated light's speed to be about 220,000 kilometers per second, which was remarkably close to modern measurements. Rømer's work laid important groundwork for later developments in physics and astronomy, demonstrating how careful observation and reasoning can uncover fundamental truths about the universe.