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Is it true that Jupiter gives off more heat than the Sun? And why?
Question Date: 2002-02-19
Answer 1:

N, Jupiter does NOT give out more energy than the sun. But Jupiter does generate heat from within.

In fact all planets generate internal heat. For the small rocky planets like Earth and Mars most of this energy comes from radioactive decay. However this internal production of heat is SWAMPED by the heat absorbed by the Sun. For the Jovian or GAS Planets however, the situation is a little different. For the outer gas giants, solar heating contributes less (because the Sun is much farther away). Internal heat is generated when a mass in a gravitationally bound object sinks closer to the center of attraction- that is, when the object becomes more centrally condensed. So for Jupiter which was hot when it formed it continues to this day to slowly contract as it cools down from its initially hot state. This is called the Kelvin Helmholtz gravitational energy release process. On top of that there is the differential motion of Helium relative to Hydrogen and because Helium is denser, as Helium sinks towards the center preferentially further potential energy is liberated as heat. The internal heat generation of Jupiter is about 6 Watts per square meter. The amount of sun energy that falls onto Jupiter is about 10 watts per square meter. So unlike the case on Earth Jupiter's output due to internal processes (contraction) is about half as large as the input due to sunlight falling on its clouds.

Answer 2:

This is a great question. It is not true that Jupiter gives off more heat than the Sun. The Sun actually gives off 1,000,000 (One million) times more heat than Jupiter does in the same amount of time. The sun is a star and Jupiter is a planet.

Stars have higher temperatures and larger masses than planets which allows for heat producing reactions to occur inside the stars. Most of the heat that planets give off comes from breaking down radioactive atoms and from reflection of the Sun's energy.

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