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Nice. Seems related to: https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature https://en.wikipedia.org/wiki/Planetary_equilibrium_temperat... The tem
by heisenzombie 6y ago
Nice. Seems related to: https://en.wikipedia.org/wiki/Planetary_equilibrium_temperature https://en.wikipedia.org/wiki/Planetary_equilibrium_temperat...
The temperature of a perfect black body in earth’s orbit would be ~255K (-18C)
(This is not the case for the technology under discussion because it’s very much not a black body)
I will point out that even at modest (astronomically speaking) distances, the solid angle of a star gets preeeeetty small. For example, a black body at just 1 light year from the Sun (just a quarter of the way to Alpha Centauri) would come to an equilibrium temperature of ~1K (assuming an otherwise empty universe). So that’s already a smaller effect than the CMB.
I think in intergalactic space, the thermal equilibrium of a black body would be absolutely dominated by the CMB.
- pdonis 6y ago> even at modest (astronomically speaking) distances, the solid angle of a star gets preeeeetty small Yes, but you're not just being irradiated by a single star. There's a whole galaxy of them. They aren't all visible to the naked eye, but they're still there, and their radiation all adds up. However, I have not done detailed calculations, so I might be overestimating, for example, what the effective radiation temperature would be of galaxies in intergalactic space.
- pdonis 6y ago> The temperature of a perfect black body in earth’s orbit would be ~255K (-18C) More precisely, of a perfect black body in Earth's orbit with the same surface area and shape as Earth.
- heisenzombie 6y agoYes, only true for black spheres. It’s size invariant though.