The Speed of Light

One of mans greatest curiosities was about light, its composition and how it propagated through empty space, even back in the days of Plato, Aristotle and Socrates. It wasn't until Galileo that the question of velocity of light was tested with the use of covered lanterns. Not too much later R mer would determine through the study of Jupiter's moons that the speed of light was 186,290 miles/sec.