Dennis J. Cowles do planetário de New Orleans dá-me uma resposta curiosa.

"For the last two decades, we’ve assumed that both Jupiter and Saturn have had a large core (10 or 20 Earth masses). The Galileo data imply that the core is smaller than we thought that it was (maybe 5 Earth masses). One group of scientists, Alan Boss among them, argues that the data may indicate that there is no core at all. This is one possible interpretation of the Galileo data, but I’m not sure that most scientists would agree. The moment of inertia implies (as you point out) that there is at least a small core.

What we need to do is send a probe to Jupiter to map the planet’s gravity. We can figure out from a good gravity map what the internal structure is, including whether or not there is a core there."