He was able to solve this dilemma by positing that the speed of light was not infinite; therefore, since Jupiter and its moons were farther away, it would take light longer to get to Earth, since it had to travel a longer distance. Using this logic he was not only able to make the equations work to predict the position of Jupiter’s moons, without regard to where Jupiter was in its orbital cycle; but, he was also able to make a first measurement for what the speed of light is.
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