[QUOTE=Musicat]
I have a good friend who insists that you can’t see colors under moonlight, as the special moon-white light makes all things monochromatic. If I show him a red object and a green object in the moonlight, and we can certainly tell the difference, he says, “Oh, that’s because it’s BRIGHT moonlight – that only works under a full moon.”
[/QUOTE]
Ouch. So close, and yet so, so wrong. In very low light situations we do see in monochrome, where raising the light some will make it possible for us to see colors again. The reason for this is not some special “moon-white light” bleaching the color out of everything. It is because we have two different types of light receptors, cones and rods. Cones, which perceive in color stop working in low light levels, whereas the rods which only see black and white become more sensitive because bright light tends to overwhelm them. One of the reasons that red light is used in areas like astronomy and photo developing is because red doesn’t overwhelm the rods as much as other colors do.
So your friend is right in that you don’t perceive color in very low light situations, but completely off his rocker when it comes to why. When light strikes the eye receptors, those cones and rods don’t care where the light is from, just how bright it is.
[QUOTE=Giles]
I was at about the same age when I had another demonstration of the speed of sound. We lived a few blocks away from a cricket ground, and if you listened to the cricket on the radio, the cheers from the crowd came from the radio a second or two before they came from the real crowd. (Even though the radio signals had probably travelled at least 400 miles, going to a central studio, then back to the local radio station).
[/QUOTE]
I’ve had a similarly interesting demonstration. My Mom lives about ten minutes away from us. We’ve been talking on the phone during thunderstorms where I head thunder through the phone before hearing it from outside. That was cool.
[QUOTE=Mangetout]
can jellyfish run on land?
if swimming is so good for you, why are whales so fat?
…
[/QUOTE]
I’ve done some time on Yahoo!Answers giving smart and often smart-alecked answers. I’ve answered the whale question before, maybe I should go back for some more punishment.