How long does it take light to travel from
(a) The Earth to the Moon?
(b) The Sun to the Earth?
(c) Jupiter to the Earth, assuming Jupiter is at its closest distance to the Earth?
(d) Jupiter to the Earth, assuming Jupiter is at its farthest distance to the Earth? The difference between the times in parts (c) and (d) was used by Danish astronomer Ole Romer to give the first experimental measurement of the speed of light. (Romer did this work in the 1670s, about the time Newton was doing his work on mechanics.)