My husband says it had something to do with greeting rather than removing one’s hat. edited to say, he said the original reason was it was when knights met each other, if they were friendly they raised their helmet visor to each other. It later became removal of the hat. He said it is one of the first things you learn when going in the military.

We have migratory Miller Moths here. We were told, on the nighly news, they use moonlight as a guidance system to find the migratory route.

I haven't the heart to say anything other than those who said that word above ... ... and thankful that mine's working well without giving me any trouble. Glad that, at age about 16, after 6 mos. or so of using ciggies, liking neither the taste, nor as a tot during the Dirty Thirties' depression learning frugality, the cost ... I had sense enough to quit! Now, just under 80 years later, I think that my heart, lungs, gut, kidneys and other parts are showing the results/fruits of their gratefulness. ole joyfuelled

Luminol ;) (technically, this answer is imprecise) I wonder how many of us own a black light. They are fun.)