"Jupiter radiates about 2.5x more energy at
Infrared wavelengths than it receives from
the Sun. . . . Jupiter is slowly contracting
under its own weight. Slow contraction
releases gravitational energy, heating the
deep interior."
I have no doubt that the radiation difference
(emitted versus received) is an experimental
fact. But what evidence do we have that the
planet is still undergoing slow contraction? Is
this only a hypothesis (what else can it be?)
or is it a fact based on observations?
It seems to me that the rate of contraction
would be too small to measure. Yes, the
liquid metallic hydrogen (below the thick
atmosphere) should be a good conductor
of heat and electricity. But this does not
explain the origin of conducted heat.
By the way, the percentage of hydrogen
in Jupiter is nearly the same as in the Sun.
But the mass of the planet is about ten
times smaller than what would be needed
to start thermonuclear burning.
Ludwik Kowalski