Jupiter puts out twice as much heat as it recieves

It's my understanding that jupiter puts out twice as much heat as it recieves from the sun. I would like to ask: Is it possible that this may be becasue fusion does take place at a rate much much more rare then in the sun. Quantum mechanics and the laws of probabilites tells us that this might be a possibility - and it would explain why it is giving off so much heat.
Maybe I'm wrong about my facts - or maybe I'm just wrong. I just thought it might have been a possibility.

 

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I am not positive, but I believe it is the result of two sources. One is the heat that came from its original formation. The other is from radioactive decay occurring in its core.

 

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I think it may be from continued gravitational contraction.

 

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All three of those I'm sure contribute to the heat, as does tidal forces. I can't help but to think though, that fusion occurs very rarely, but does occur - and not all in one place, but as a function of probability in different places where pressure is greatest in jupiter's core.

 

Well, the all-knowing Wikipedia says deuterium fusion requires a body with a mass 13 times that of Jupiter's. Genuine stellar hydrogen fusion is said to occur in objects with a mass upwards of around 90 Jupiter masses.

 

1. Residual heat from formation
2. Hydrogen phase transitions

 

I am sure there is nowhere near enough pressure or temperature for fussion to occur.

 

because it's almost a star.

neptune also radiates more than twice times as much energy as it absorbs from the sun.

 

How about plain ol' Friction?
With Different band rotion rates and some of these bands also rotating in different directions,coupled by it's general high velocity Spin rate and differing compositional elements.

Wouldn't this basically kinetically be like rubbing two sticks together?

 

Ya, I suppose you guys are right. But I still think it's within the realm of possibility. It's really a tremendous amount of energy it is giving off if you add it all up. Can't this only be attributed - because of conservation of energy - to only effects of using the planets angular momentum, gravity, chemical, or nuclear? I don't think it could sustain that much energy loss if the heat was due to the heat of formation (unlikely since most of it is gas) that would also mean that it would be cooling over the course of 4 billion years or more and the energy that is excaping now is the least amount of energy that has excaped. Crunch the numbers - it doesn't seem likely.

And friction still has to get it's energy from somewhere - not discounting it just trying to explain it.

 

Tortise,
I have been googling this a little since my last post. It seems there is no consensus on exactly what the heat source is: multiple sources have been presented. There is, however, universal agreement that fusion is not one of the heat sources.

1. Residual heat
2. Continuing gravitational contraction.
3. Helium condensation (I got that wrong in my earlier post. I thought it was a hydrogen phase change.)
4. Nuclear fission

You are right about the friction. To generate the motion calls for a heat source.

 

Thanks Hipparchia.

One more point though, correct me if I'm wrong (there is probably a flaw in this thinking somewhere: If fission heats planets, then the moon should also be heated by this since it is composed of mostly the same thing as the earth, and this is also the theory of how the earth gets heat from it's interior (which is also quite a bit of heat). And obviously the moon is not heated in this way. By observation alone, there seems to be a tipping point past which planetary bodies are heated from their cores. If the heat of formation, this heat eventually dissapates. This has not happened in the earth's case, infact the heat is still intense, and causes the techtonic plates to move for example. If the earth was cooling, then we would expect the speed of those plates to be slowing down over the course of billions of years wouldn't we? Really, this is a tremendous amount of energy. Can we attribute earthquakes, volcanos, and everything else that is caused from the heat of the interior of the earth to radioactive decay? If that were true we would get decaying matterial out of the volcanos wouldn't we?

 

A lot of the Earth's heat at the core is left over from its formation. But the radioactive decay has added a lot of heat to that.

Most of the radioactives are very dense. As such, they sank to the core of the earth in its early life, when all was molten. They pretty much stay there, so that the upper mantle has radioactives in about the same porportion as the crust.

The Moon was formed mostly from material from the crust and upper layers. So it was much poorer in radioactives than the Earth's core. That, and its small size, are why its core is much cooler than Earth's.

 

What about (in the case of the Earth/Moon system) the friction caused by tidal effects? There are tides in the Earth as well as in the oceans, and the Earth is 81 times more massive than the moon, so its effects on the moon are immense. Isaac Asimov wrote a science article on the subject years ago, can't remember the title, sorry.

 

Two very good points Poincare's and Xylene. I know that tidal effects produce a lot of heat, but why then does the moon not exhibit heat from this? Am I right that mathematically the moon gets as much energy as the earth does from tidal forces from the earth / moon relationship? If that is true it puts the energy into perspective - it can't be a significant fraction of the heating of the earth. Remember that the moon causes the tides and not the waves in the ocean.
I can't help but to maintain that there is much to learn about planetary heating. Did you know that there are many many heat vents that are in the ocean - the average temps are around 750 deg. F

The energy from earthquakes, volcanos, movement of plates, thermal vents, and heat conducted through the soil to the atmosphere: All this energy can't be residual can it? Maybe it can:

http://www.geology.sdsu.edu/how_volcanoes_work/Heat.html

 

I just want to say two or three more things: It's not suprising to me that neptune or uranus also give off twice as much energy as they recieve from the sun because they recieve so much less energy from the sun that the effect of any nuclear decay would also have to be much less. To me this is an argument that something unknown may be going on. Jupiter is almost entirely hydrogen and He. The fraction of heating should be much less for jupiter since the elements are most certainly a much much lower fraction of the mass of the planet. Insted what we see is that these two other gas giants put out much less heat - remember jupiter is much closer to the sun.

Think about it: Jupiter as a fraction of it's mass has less matterial that could decay then the those other two gas giant planets, yet puts out more exrta energy.

So by both of those factors, (less fissionable matterial and more energy output then other planets period -even per ton) jupiter should have less heat output as a fraction of the heat they get from the sun then the other gas giants (not that the distance from the sun has anything to do with the extra heat - just a good yard stick so to speak). This argues strongly for a better understanding.

 

We need numbers.

How much heat does Jupiter put out?
What amount of fissionable material would be required to make that heat?
How much fissionable material might Jupiter contain?

 

I think you are mistaken about the result, as you have considered only the physics, and ignored the chemistry. Uranium and the other fissionable elements are lithophile elements, not siderophile. They preferentially sequester themselves in silicate minerals, not those of iron and nickel.

This extract expresses the situation quite clearly. The whole article is worth reading:

RADIOACTIVE ELEMENTS IN THE CORE
Those that have suggested the presence of radioactive elements in the Earth's core have usually done so in order to offer an alterative explanation for the power needed to run the geodynamo and/or as a way to explain where the volatile elements are in the Earth. ..............
Likewise it is not possible that U or Th or both are in the core. If U is in the core, there must also be Th there too and in chondritic Th/U proportions, since their chondritic ratio in the primitive mantle would dictate this. In the absence of experimental evidence showing similar solubility for U and Th in Fe-S and Fe-S-O liquids at high pressure and not other refractory lithophile elements, one must conclude that there is no U or Th in the core.

Source:http://mahi.ucsd.edu/cathy/SEDI2002/ABST/SEDI1-2.html

Tortise, although, as you say, Jupiter is mainly hydrogen and helium, it is estimated that its core is a rocky/iron mass equal to about ten Earths. There will be a goodly amount of radioactives in that.

 

I'll post numbers tomorrow must sleep soon. but here are some links: http://nssdc.gsfc.nasa.gov/planetary/planetary_home.html
http://www.nineplanets.org/jupiter.html

"This enormous planet radiates twice as much heat as it absorbs from the Sun."http://www.enchantedlearning.com/subjects/astronomy/planets/jupiter/

 

The Earth does have tidal effects on the Moon. And the Moon has some seismic activity as a result. Moonquakes happen fairly often. This was just on Nasa's APOD yesterday...

http://antwrp.gsfc.nasa.gov/apod/ap060327.html

But the heat generated is not enough to melt rock.