The speed of light was first estimated in 1676 by a Danish Astronomer who was timing the eclipses of Io caused by Jupiter. He noticed the period between eclipses increased with Earth’s distance from Jupiter and guessed it was because light had to travel a longer distance.
Rømer’s determination of the speed of light Ole Rømer (1644–1710) was already a statesman in his native Denmark some time after his discovery of the speed of light (1676). The engraving is probably posthumous. Rømer’s determination of the speed of light was the demonstration in 1676 that light has a finite speed and so does […]