[Joe L. Ogan]

If the sun is powered by electricity force and it converts this into Radiant Energy, which is probably Kinetic Energy, May this be converted back to Electrical Energy?

[JP]

There's a lot of questions here.
1)

If the sun is powered by electricity force...

It isn't, primarily.  There are a lot of forces at work within the sun, but its primarily a giant nuclear reactor.

2)

and it converts this into Radiant Energy, which is probably Kinetic Energy,

Most of the radiation we get from the sun is electromagnetic radiation, which isn't kinetic energy.  The sun also sends out massive particles, which do have kinetic energy.

3)

May this be converted back to Electrical Energy?

  Yes.  Solar panels are a good example of something that can do that.

[Eric A. Taylor]

The sun is powered by nothing more than gravity. The weight of gas in the sun is so high it squeezes the core so hard that the hydrogen in it's core fuses together to form helium. Atoms don't like to be close together. This is why solid objects feel solid. They really aren't solid at all.

Imagine blowing up an atom of hydrogen which is composed of 1 proton and 1 electron. Most hydrogen atoms don't not have any neutrons. If you made the proton large enough to see. Perhaps the size of a sweet pea inside a football stadium the electron would be about where the "nosebleed" section is. Because of quantum physics we can't say WHERE the electron is. It's not at seat 44b say, rather the electron is spread out over all possible locations. Think of the electron as a drop of ink on a paper that somebody has smudged with their finger. The ink drop is no longer in one place but is spread out all over the page. Every thing else between this pea sized proton and the electron is empty space! The reason atoms don't pass by each other is the electrons in both repel each other very strongly. When you touch something the electrons in your hand repel the electrons in whatever you touch. so you don't really touch it. You hand is pushed away by a force field a tiny fraction of a mm away.

But if you hit something really really hard the atoms in your hand will fuse with the atoms in whatever you hit and become something else. Usually that something else is a little lighter than the sums of what your hand and the thing you hit were made of. The missing mass is converted to energy according to E=MC² this is bad news for you because C² is a huge number, meaning your hand will be ground zero for a nuclear explosion. Your parents might get mad at you for hitting your sister that hard so please don't hit her THAT hard. Better yet, don't hit her at all no matter how annoying she is. (The bomb dropped on Nagasaki, Japan converted 1/6 of a gram of Plutonium to produce it's huge blast. A bit of plutonium smaller than this period.)

Atoms inside the sun are squeezed together this hard, so you can see a nuclear explosion at any time of day assuming the sun is out. But it's so bright please don't look directly at it. The energy from the sun is pure nuclear energy powered by nothing more than gravity.

[Bored chemist]

"The sun is powered by nothing more than gravity."
No it's not.
If it were then the sun would have gone out billions of years ago.
It's powered by nuclear fusion.

[Eric A. Taylor]

Yes it's powered by nuclear fusion but the ENERGY that drives it is GRAVITY. Humans have been able to produce nuclear fusion on Earth but these reactions only lasted a few tiny fractions of a second. When a fusion reaction happens there is a huge amount of energy produced. This energy tends to push atoms apart. In my other reply I said only 1/6th of a gram of plutonium was converted to energy. The rest was blasted all over the city. It was from this that all the radioactivity came from. Had the bomb converted ALL it's plutonium into energy there would have been NO lingering radiation (there would have been a lot of gamma rays in the blast but gamma ray radiation is a different kind of radiation and would not have lingered) Gravity in the sun pushes everything together. This is why Jupiter isn't a star. There is not enough gravity in it's core to push atoms together.

[rosy]

Saying that the sun's energy comes from gravity is a bit like saying that the energy in a bonfire comes from a the match used to light it.
In order for the reaction to get going, the matter has to be held close enough together and in the sun, this is a result of gravity (it may be possible to achieve this by other means to exploit fusion on earth). But this is not where the energy comes from, the energy is released by nuclear fusion.
Likewise, a bonfire needs some energy input to get the fire started, but the energy after that is not coming from the match but from the fuel.

[Eric A. Taylor]

Saying that the sun's energy comes from gravity is a bit like saying that the energy in a bonfire comes from a the match used to light it.
In order for the reaction to get going, the matter has to be held close enough together and in the sun, this is a result of gravity (it may be possible to achieve this by other means to exploit fusion on earth). But this is not where the energy comes from, the energy is released by nuclear fusion.
Likewise, a bonfire needs some energy input to get the fire started, but the energy after that is not coming from the match but from the fuel.

I beg to differ. Your analogy is not valid. In a fire if you take the match away after the fire is going it will have no effect on the fire. If you were able to somehow remove most of the mass of a star without removing any of the core where the energy is produced the core will expand out and nuclear fusion will stop.

In fusion energy production magnetic fields are used to hold together a ball of plasma. If the field is lost the reaction will stop. This is one reason nuclear fusion would be much safer than fission for power production. In fission engineers need to think carefully about how to stop the reaction if it gets out of hand. In older reactors like 3 Mile Island and Chernobyl the hotter the core the faster the reaction. (In modern fission reactors this problem has been resolved.) Perhaps gravity doesn't DIRECTLY produce the power but it does sustain it.

[Madidus_Scientia]

Gravity makes the fusion possible, but you were saying that the energy comes from gravity, it doesn't. That's all they were saying.

[Eric A. Taylor]

The energy comes from the matter. 1 helium atom is a little lighter than the hydrogen atoms that make it up. This difference is released as energy according to E=MC²