(February 10, 2016 at 8:32 am)SteelCurtain Wrote:(February 10, 2016 at 7:59 am)Alex K Wrote: Is the surface of the moon really in thermal equilibrium with the light it reflects? I think this is a crucial difference between the sun and the moon.
Wouldn't it have to be? Otherwise the surface of the moon would either store thermal energy or run out, yeah?
No, imagine the moon is very far from a very hot incandescent source that emits X rays. The light impinging on the moon would still have a color temperature of millions of degrees. Now let's say the moon absorbs 50% of impinging X rays and reflects the rest.
The moon would seem to an observer to shine with a spike at the color temperature of millions of degrees, especially to a creature with X ray vision.
Does that mean the moon will attain a surface temperature of millions of degrees? No. It half of X rays photons it does not reflect is so few in number it barely elevated the surface of the moon above absolute zero.
So there.