Reply to post: Re: Eight times brighter than the Moon?

Chinese biz baron wants to shove his artificial moon where the sun doesn't shine – literally

bombastic bob Silver badge

Re: Eight times brighter than the Moon?

"It'll be a shaped mirror focussing on a relatively small area."

a city isn't all that "small" but yeah, not like the moon which is competely UNfocused reflection.

A space-mirror would have solar energy reflected from it based on the total surface area of the mirror. if the mirror were exactly the size of the city, perfectly focused, etc. it would light it up like daylight. A fraction of the surface area of the city means an equivalent fraction of the light level, and so HOW bright did you want it? HOW big does that mirror need to be? 1/10 the surface area of a city with a population THAT large? Oh let's just ballpark it at 100 SQUARE MILES!!!

(article said 10 to 80 mile area - is that radius, diameter, or square mileage? if square miles, then make the mirror about 1/10 of that - but 10 square miles is only ~3 miles or so on a side, maybe the general area around his house but that's about it)

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