Hey...
...even Arthur gets it wrong*. But in his end notes I think he acknowledges it's likely in Neptune, not in Jupiter, just sounded good.
*Actually he makes some pretty spectacular gaffes, notably in "Songs of Distant Earth" he describes the impossibility of star-travel as due to the squaring of the fuel mass NOT the mass-ratio. Just one of his egregious liberties with the facts.
But I still read him!
Adam