This web page is an explanation by Keith Dixon-Roche of gas planets and how they differ from stars and other planets.
It is currently claimed that the gas planets comprise mostly gas (hydrogen and helium).
It is also claimed that most of our (Earth's) surface heat is provided by our sun.
These arguments are contradictory. Similar, in fact, to the current argument that a star's energy is from fusion and yet it grows in size with age.
Jupiter is 1.89819E+27kg and has a radius of 6.9911E+07m. Together these create a gas planet with a density of 1326kg/m³; there is no such gas.
Just from looking at the planet, it is obvious that Jupiter's gases are a lot heavier than helium and hydrogen, neither of which generates the colours we see. Jupiter's gases are complex [heavy] molecules. They therefore require temperatures higher than we have here on the surface of Earth to exist as such.
It isn't difficult, therefore, to understand that Jupiter is not simply a ball of hydrogen and helium.
Bearing in mind that the temperature of outer-space is less than 3K, and for matter to exist as a gas it must be hot (>3K):
If Earth's surface heat comes from our sun, then so does Jupiter's. But being so much further from the sun, Jupiter's surface should be colder than Earth's.
The surface of Mercury's dark-side and our moon are both cold, but they are much closer to the sun than Jupiter.
It isn't difficult therefore, to realise that the sun cannot be responsible for planetary heat.
But we also know that Jupiter, Saturn, Uranus and Neptune (all gas planets) must be generating considerably greater heat than here on Earth to sustain their gas clouds.
So where do the gas planets get their heat?
Having resolved planetary spin - there even exists a simple calculator that accurately predicts the rotary characteristics of all the celestial bodies in our solar system - we now know the source of internal heat in orbiting celestial bodies. And also, that the greater a satellite's sub-satellite mass, the more internal heat (and magnetic field) it will generate.
Our sun has collected a far more massive sub-satellite population than Jupiter, so it should generate more internal heat.
Jupiter has collected a far more massive sub-satellite population than Earth, so it should generate more internal heat.
Earth has collected a greater sub-satellite population than Mercury or Venus, so it should generate more internal heat.
Mercury's far side is cold. So, we know it has no internal heat.
Venus' [surface] heat is due to the suns radiation (twice that of Earth) heating the water spewed on the planet's surface due to internal spin-friction generated by the conflicting energies induced in its core and mantle matter by the sun's PE (at its core) and the torque induced in its mantle matter by the sun's rotation, but it isn't much. From satellite imagery, it is obvious that Venus generates very little tectonic plate activity.
In fact, most (if not all) of a satellite's surface heat is due to planetary spin; if an active planet lost its moons, it would become cold.
In any solar system:
Its force-centre's superior mass (gravitational pull) will prevent its nearest orbiting planets from trapping sub-satellites (moons) of their own. A force-centre's gravitational influence on its satellites diminishes with distance, leaving its farthest planets free to collect the most sub-satellites (moons). In our own solar system, Pluto is by far the most active planet. It has collected such a [relatively] massive sub-satellite population that it is being pulled into a local orbit, preventing the orbital energies (PE and KE) from acting on the same centres; so, no internal friction, so no internal heat.
If a planet has no sub-satellites, it will generate very little internal heat and no magnetic field.
If a planet has collected relatively little sub-satellite mass, it will generate considerable internal heat but insufficient to melt its surface matter. The relative rotation between a planet's mantle and crust matter will, however, drive tectonic plates releasing internal gases and water onto its surface.
If a planet has a substantial sub-satellite population, it will generate sufficient internal frictional heat to melt all of its matter, including its outer surface, thereby creating extensive gas clouds of heavy atoms and molecules.
The heat within a [bright] star is also generated by planetary spin, but stars have collected so much sub-satellite mass, and have such a massive [galactic] force-centre, that the internal heat they generate is sufficient to achieve the neutronic temperature in their core elemental matter. This will result in the continual creation of elements with a neutronic ratio greater than 1.6, thereby releasing neutron energy (fission). Around 99.598% of the heat energy generated in our sun is from fission.
You will find further reading on this subject in reference publications(55, 60, 61, 62, 63 & 64)