Jupiter now has 79 known moons, 22 of them have yet to be named. Back in 1610, an astronomer named Galile Galilei was [one of] the first to recognize that Jupiter had moons when he spotted 4 of them. One of them, Io, has observed orbital radius of 4.20×10° m and an observed orbital period of 1.77 days. a. Using this data from Io, what is the mass of Jupiter that Isaac Newton would have determined when he Wrote Principia in 1686? Another "original" moon of Jupiter, Europa, has an orbital radius of 6.70 × 10 m. Show how Johannes Kepler would have determined its orbital period in Earth days?

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