The first reliable method developed to measure the speed of light involved
A) careful observation of the motions of the moons of Jupiter at different times in Jupiter's orbit.
B) observing the opening and closing of shutters on lanterns on hilltops separated by a known distance.
C) bouncing a beam of light off several different mirrors.
D) making careful measurements of the orbital path of the Moon around Earth.

Question

Quizplus · Accepted Answer

The first reliable method developed to measure the speed of light involved careful observation of the motions of the moons of Jupiter at different times in Jupiter's orbit. This method was developed by Ole Rømer in the late 17th century and was based on the fact that the time at which the moons of Jupiter appeared to pass behind the planet varied depending on the position of Earth in its orbit. By carefully measuring these variations, Rømer was able to estimate the speed of light to within about 25% of the modern value.

The First Reliable Method Developed to Measure the Speed of Light