[Lewis Thomson (OP)]

Thomas has presented this cosmic question to us at The Naked Scientists.

"With the findings of the Juno mission, Jupiter has rock core with a metallic hydrogen layer then gases. So what is Jupiter now? Is it still a gas giant?"

How should we identify it? Leave your definitions below...

[chiralSPO]

yes, still a gas giant. it's mostly gas and it's giant. It's no surprise that rocky material would be at its center—either the rocky core predates the huge envelope of gas around it (think of the early solar system with lot of hydrogen floating about, and a planet massive enough that not even hydrogen can leave its atmosphere, once captured. it would continuously absorb more hydrogen from the surrounding space until there was nothing left to capture. luckily juptier did not find enough hydrogen to become a star!)—or there was enough gas to self-coalesce, and any time an asteroid (or space dust) gets captured, it falls alllllllll the way down to the center!