# If there was steal between earth and the sun instead of a vacuum

1. Jun 9, 2010

### marsh8472

I'm witnessing an argument elsewhere about whether a vacuum is a good insulator in space.

Person 1 said this:

Person 2 said this:

I said this:

what would really happen if the vacuum between us and the sun were replaced with steel?

2. Jun 9, 2010

I think a vacuum is the best insulator.

edit - but in the steady state, it may not make any difference. The sun would heat up the steel until its in equilibrium and then it would heat the earth until the earth is at equilibrium.

3. Jun 10, 2010

### marsh8472

Yes this is what I'm after, the steady state after the sun has been explosed to steel 63 million miles thick. Once equilibrium is reached, what would be the tempuratures along the steel sphere surrounding the sun. Given that the surface of the sun is around 6,000 Kelvin. This should be a relatively easy thing to calculate right?

4. Jun 10, 2010

### marsh8472

well actually according to this:

the atmosphere of the sun gets pretty hot so i'm not even sure what would be an appropriate value to use as a tempurature. It would be nice to have an equation where I can input my own core tempurature and see the various tempuratures of the steel at distances from the sun.

5. Jun 10, 2010

I dont think it would have any effect in the steady state. Once you are in equilibrium it would be the same.

Consider the power radiated from the sun, just outside of its surface. This must be equal to the power being radiated at some far distance, due to conservation of energy. If you put something in between that wont change this, the sun is still pumping out energy and that energy will still flow out. (Im ignoring the possibility that the metal could reflect energy back into the sun, thus changing the equilibrium position)

6. Jun 10, 2010

### Lsos

I'm not sure it would make a difference. Surely the steel would take longer to transfer the heat to the earth (through a vacuum it gets transferred at the speed of light), but once the heat started flowing, I would think it would continue to flow at the same rate.

I imagine even if we put the best insulator between us and the sun, the same thing would happen.

Remember, the earth's interior is a set temperature, and it's not making energy. The sun IS making energy, and that energy has to go somewhere. If something is keeping that energy in, then the sun will simply get hotter until the insulator gets rendered useless.

7. Jun 11, 2010

Staff Emeritus
Exactly.

8. Jun 11, 2010

### n.karthick

But I think in the other way. I feel the Person 2 is right.
Assuming 'x' amount of energy is coming from Sun to Earth. Since nothing is there, vacuum is a perfect insulator and energy is only radiated, but if we assume steel is there, then it will conduct heat and so lot of heat will reach earth isn't?

9. Jun 11, 2010

### Phrak

The sun would be hotter in steady state conditions. Does this make a difference?