We all learn that the speed of lights, travelling from sun to earth is about 299,792,458 metres per second way back in the early secondary school; but do you remember who discovered it & how was it discovered?
Earlier scholars thought that light travelled instantaneously, but it was a Danish astronomer, Ole Romer, who in 1676 said otherwise, that it travelled at a limited speed. Which even Galileo tried to determine in 1638, but he failed as he realized that light travelled too fast to measure with the “trick” he used. He involved 2 people standing on a hill top miles apart with a lamp and one of them would flash their lamp at the other, who would respond by flashing back immediately. Although, he did determine that light travels 10x faster than sound.
Decades later in 1673, Roemer noticed the time lapse between the eclipses of a Jupiter moon called Io, and by monitoring the time difference, he determined that “light seems to take about 10 -11 minutes to reach a distance equal to the half-diameter of the terrestrial orbit around the Sun.” Which led to the estimation that, light travels at about 200,000,000 m/s, around 26% below the established speed.
By: Archa Dave
