When was the speed of light first accurately calculated?
A. When Galileo and his assistants uncovered lanterns at different hills and measured the time it took to see the light.
b.When Roemer used the eclipsed moons of Jupiter along with Earth's orbit around the Sun to compare different speeds over time.
c. When the Hubble Space telescope took the deep field pictures and measured how long to keep the aperture open to get the image.
d.When Michelson used a rotating octagonal mirror to reflect light to a mirror on a distant mountaintop, which then reflected the light back to the rotating mirror and into an eyepiece.