It also found that Ganymede, the largest moon in the solar system, has a magnetic field.

ECONOMIST: Galileo and Jupiter

The existence of a magnetic field on Ganymede, the biggest moon of Jupiter.

CNN: Galileo moves on to Europa

And water would be all the more exciting on Ganymede because it is the largest moon in the solar system (larger even than the planets Mercury and Pluto) and, like earth, it has a permanent magnetic field that protects part of its surface from bombardment by certain sorts of life-destroying radiation.

ECONOMIST: Blue moon