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> So the maximum temperature that system can achieve is much less that your mirror/magnifying glass system. Why? If the moon were a perfect black body, but wit
by baddox 8y ago
> So the maximum temperature that system can achieve is much less that your mirror/magnifying glass system.
Why? If the moon were a perfect black body, but with a few small perfect mirrors on the surface to bounce a bit of sunlight towards Earth, couldn't we (in theory) focus that tiny bit of sunlight to heat something up to the temperature of the Sun? There may not be enough solar radiation to make it feasible in practice, but it seems like you need to actually do the math instead of just saying "the moon's surface temperature isn't high enough to start a fire, Q.E.D."
- stcredzero 8y agoWhy? If the moon were a perfect black body, but with a few small perfect mirrors on the surface to bounce a bit of sunlight towards Earth, couldn't we (in theory) focus that tiny bit of sunlight to heat something up to the temperature of the Sun? To get past the diffraction limits, those "few small perfect mirrors" on the Moon would have to be gargantuan. (If I'm remembering correctly, they'd be the size of the alien space ships in Star Trek that make the Enterprise-D look teeny.) Otherwise, viewed from the surface of the Earth, those mirrors would just constitute a minuscule brightening of the sky in the direction of the Moon.
- neltnerb 8y agoBut you could instead cover the whole moon with some kind of dust that reflects 12% of incoming irradiation in average. You're arguing technical problems with a toy example illustrating an unrelated point.
- stcredzero 8y agoEach of those specks of dust modeled as a tiny mirror would be very much subject to diffraction limits. This would basically make what you propose equivalent to an approximate black body that's like asphalt with 12% albedo. Dandy.