Another way that you could look at it, is as LeifCarrotson said below, that the moon is like a mirror. If RM's idea that the sun's light reflected from the moo

Another way that you could look at it, is as LeifCarrotson said below, that the moon is like a mirror. If RM's idea that the sun's light reflected from the moon could not start a fire was true, what makes the situation different if you are reflecting the sun's light from a cold mirror? Can the light from the mirror not cause a higher temperature than the temperature of the mirror? We know that mirrors (and even lenses made of ice) can be used to create temperatures at their focus high enough to melt them. So, what is it about the moon that is different from a mirror, besides a lower reflectivity? I suspect that RM just got a little lost in the weeds on this one. I remember making a similar mistake in undergrad when I was thinking about a problem with two light sources with an optical filter in between. The key insight I needed to make was that the filter was a physical object with its own temperature. Thinking about things like this is how you develop what physicists call "physical intuition".