Who measured the velocity of light first?

Who measured the velocity of light first? 

(1) Galileo 

(2) Newton 

(3) Romer 

(4) Einstein 


Answer: (3) Galileo is often credited with being the first scientist to try to determine the speed of light. Galileo’s experiment was carried out by the Accademia del Cimento of Florence, Italy, in 1667, with the lanterns separated by about one mile, but no delay was observed. The actual delay in this experiment would have been about 11 microseconds. The first quantitative estimate of the speed of light was made in 1676 by Romer. From the observation that the periods of Jupiter’s innermost moon Io appeared to be shorter when the Earth was approaching Jupiter than when receding from it, he concluded that light travels at a finite speed, and estimated that it takes light 22 minutes to cross the diameter of Earth’s orbit. 

Who measured the velocity of light first?   (1) Galileo   (2) Newton   (3) Romer   (4) Einstein


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