Here are the average distances of Jupiter's four largest moons from the planet:

* Io: 421,700 kilometers (262,000 miles)

* Europa: 671,100 kilometers (417,000 miles)

* Ganymede: 1,070,400 kilometers (665,000 miles)

* Callisto: 1,882,700 kilometers (1,169,000 miles)

It's worth noting that these are average distances. The moons' orbits are slightly elliptical, so their distances vary slightly throughout their orbits.