On Sept. 25, 1644, Ole Roemer was born in Aarhus, Denmark. Beginning in 1662, he studied at the University of Copenhagen with physicist Erasmus Bartholin, who tasked him with editing the manuscripts ...

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch ...

Light is faster than anything else in the known universe, though its speed can change depending on what it's passing through. When you purchase through links on our site, we may earn an affiliate ...