The full moon is nine times brighter than a half-moon

[JamesF]

I read that in another thread. Whilst I can see that it might be true, and have no specific reason to doubt the original poster, it also has the ring of something that becomes an urban legend through repetition and whilst I can find lots of people repeating it on google, I can't find anyone actually demonstrating it from first principles. So...

Can anyone justify the assertion through observation or direct calculation? The best I can do is to justify why it might appear four times brighter...

James

[RogerTheDodger]

Not quite the same but it may help...

10 Things You Didn't Know About the Moon | Moon Photos, Moon Facts | Space & Solar System Facts & Information | Space.com

[GHarris]

I've been reading "Night Has A Thousand Eyes" by Arthur Upgren recently and it discusses the topic a bit. I was wondering whether to quote from the book and then noticed that it's on Google Books anyway:

Night Has A Thousand Eyes - Google Books

[Crunchard]

Nice list there Roger