Speed of light

Estimated speed of light. Galileo tried to record speed of light, but failed. Roemer observed Jupiter's satellites from Paris Observatory, found eclipses were earlier at times of year when Earth was approaching Jupiter, and later when receding. Estimated c to be 3/4 of its actual value.
 Olaus Roemer Denmark 1675 Speed of light

Estimated speed of light. Galileo tried to record speed of light, but failed. Roemer observed Jupiter's satellites from Paris Observatory, found eclipses were earlier at times of year when Earth was approaching Jupiter, and later when receding. Estimated c to be 3/4 of its actual value.