Hi Guys

Basically Jupiter is too hot for a stable ocean. Sounds crazy since the visible outer layers are so cold, but temperature goes up quickly with pressure and the temperature is way, way past liquid water stability by the time the atmosphere is dense enough to support liquid water above it.

Ben Bova's "Jupiter" made a decent attempt at explaining it - it came from comets, and thus was a superficial layer, a water veneer above the super-compressed H/He beneath. Isaac Asimov suggested a huge liquid water layer back in the 1960s - 17,000 miles thick - but these days we know that Ice VII forms above about 22,000 bar pressure. Thus about 100 km of ocean on Jupiter before it turns to ice - or super-critical fluid (gas as dense as the liquid phase, but above scaldingly hot)!

However the atmosphere isn't dense enough - H/He is only as dense as water above ~ 200,000 bar or so. And even an adiabatic atmosphere hits ~ 5500 K by that pressure. I imagined a deeper solid layer of decomposed methane (i.e. Carbon-as-diamond) to justify the Bova scenario but there's too much convection for that to work. Jupiter churns up material from its very guts.

Adam