Three. Ganymede, Io and Callisto.
See link for pictorial representation
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jupiters ice moon is Io
we can't use jupiters moons for anything because fistly we can not get out that far to reach Jupiters moon and if we could it would take thousands of years and Jupiters Moons would be to big to do anything with anyway. so the answer to What could Jupiter's moons be used for? is....Nothing.
it's moons
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Socrates, Gallileo
Yes. The moons size is 1/6th of earths so it can fit in the earth.
Phobos is the larger of Mars' two moons. It has a diameter of about 22.4 kilometers, while Deimos is smaller with a diameter of about 12.4 kilometers.
Our moon, the earths moon, is the fifth largest moon in the solar system. Ganymede is the largest moon (a moon of Jupiter), then Titan is the second largest (moon of Saturn), then third is Callisto (another moon of Jupiter) and the fourth largest is Io (another of Jupiters moons).
Jupiters Moons
12742 km / 3474 km = 3.67
2½ Moon Diameter = Earth's Diameter- 1 Moon Diameter. Earth's Diameter = 7/2 Moon