[s1artibartfast]

I think that helps. You’re saying that because the sun is not a Point Source and the rays aren’t parallel.

Following that logic, couldn’t you still put a dyson mirror around thesis and earth raising the sun and earth temp above 5700? This would raise the temp of both above 5700.

[qndreoi]

Interesting idea. I think if you put perfectly reflective mirrors inside a Dyson sphere larger in radius than Earth's orbit, the photons would bounce around until they hit the Sun, Earth, the Moon, Venus or Mercury. It seems before too long, (a few reflections), the radiation would be uniform from all directions throughout the volume of the sphere. The mirror would get as warm as all the planets, and would fail at some not too extreme temperature. Unless I'm missing something.

[s1artibartfast]

I Im not sure that the mirror has to be at the same temperature as a heat source. The area of a dyson sphere at earths orbit would be 2.810^23 m^2 The area of the sun is 610^18 m^2.

This is where my understanding of optics and reflections breaks down. How much heat/kinetic energy is transferred to a mirror when it reflects a photon?

From a heat transfer perspective. the dyson sphere has 100,000X the surface area of the sun to radiate heat and 1/100,000 the photon flux hitting it's surface. Based on this I would expect it to be cooler.