Science Porn

[Anomalocaris]

I mentioned the light temperature.thing in detail above, I think the crucial difference if you replace the moon by a mirror is that the mirror would preserve the etendue of the sunlight whereas a scattering surface greatly increases it, and so we lose the ability to concentrate great amounts of intensity by just using an idealized lens.

Low etendue of the moon is because of what? That it only reflects a small portion of sun light falling on it?

Yes, but shouldn't the etendue just of the black body radiation, not even the reflected light, of the day side of the moon be enough to to set many things on fair if only oxygen is available?

The surface temperature in the daylight side of the moon is about 140C.  Even if the moon is perfectly black and reflected nothing, it's own black body radiation ought to be able to heat an object otherwise unable to shed heat to the same temperature as itself.  Many things can catch fire at 140C.

So the key seems to me is to prevent the object undergoing concentrated moon light from reflecting the moon light, or shedding heat itself through its own black body radiation.  The key is not to concentrate moon light beyond its original etendue.