Who was the first scientist to successfully measure the speed of light using observations of Jupiter’s moon Io?
AIsaac Newton
BGalileo Galilei
CAlbert Einstein
DOle Rømer
Correct answer
D. Ole Rømer
Explanation
In 1676, Ole Rømer, a Danish astronomer, was the first to successfully measure the speed of light by observing the apparent changes in the timing of Jupiter’s moon Io as Earth moved closer to or farther from Jupiter.