Radiative equilibrium in near-Earth space

[nugae]

Project a pig P from a spacecraft in near-Earth orbit. Assume that P is rotating rapidly (or, equivalently, that it is perfectly conductive).

What temperature will P reach when it is in radiative equilibrium with the Sun on the one hand and the CRB on the other?

The Stefan-Boltzmann law gives 278°K (at least according to Wikipedia) if the pig is a black body without an atmosphere, which seems reasonable though I haven't actually checked the calculations in detail.

This question may be turning into "how un-black is a pig?". Presumably one would need to look at the albedo of pigs (either black ones or white ones) at different wavelengths. Any references would be welcome: people might have more figures on them than pigs, and, both being mammals, will probably have similar radiative properties.

If a body absorbs 30% of the radiation that a black body would, will it also emit 30% of the radiation that a black body would, or is there no necessary connection between these figures?

 

[marcusl]

This question may be turning into "how un-black is a pig?". Presumably one would need to look at the albedo of pigs (either black ones or white ones) at different wavelengths. Any references would be welcome: people might have more figures on them than pigs, and, both being mammals, will probably have similar radiative properties.

The emissivity of most organic materials (skin, paper, etc.) is close to 1 in the infra-red. For human skin it's 0.95-0.98, regardless of skin color, dropping to about 0.9 in the near-IR.

If a body absorbs 30% of the radiation that a black body would, will it also emit 30% of the radiation that a black body would, or is there no necessary connection between these figures?

Emissivity is reciprocal for absorption and radiation.

 

[cesiumfrog]

If a body absorbs 30% of the radiation that a black body would, will it also emit 30% of the radiation that a black body would[..]?

If it didn't, would energy be conserved?