TIL that the speed of light was first measured accurately in 1676 by Danish astronomer Ole Rømer using observations of Jupiter’s moons, without modern technology

https://en.wikipedia.org/wiki/R%C3%B8mer%27s_determination_of_the_speed_of_light
#til #todayilearned
https://www.reddit.com/r/todayilearned/comments/1fz9u2y/til_that_the_speed_of_light_was_first_measured/