What color is the moon?

I asked you all this question and got some very interesting answers.

Silver like aluminum

white, like the color of clouds

Chalky, like ash

silver, kind of like an old coin

gray like pavement

silver like your mother's hair

milky chalk

gray like a used eraser

white, like a diamond

But among all the varied responses and interesting comparisons, you all pretty much agreed: The

moon is a very light color, something like this.

But what if I told you it was actually more like this

[MUSIC]

When our brains are trying to figure out what color something is

the first thing we do is try to figure out how bright it is.

This side of the apple looks like a brighter color than

the side away from the light, we can see that is so,

but our brains are able to take this lighting into

account and we know that the whole apple is the same red.

If a car drives out of a dark tunnel, we don’t assume the car magically

changed color, because our brains correct for differences in all the light

in whatever scene we’re looking at.

But that doesn't always work so well.

Here's a white square

No, here's a white square.

No, here's a white square

Wait a second, what is going on here?

All these squares are the same.

And you may have seen this famous illusion before. The two lettered squares are actually the

same color.

Even when the light in a scene doesn’t change, the colors surrounding an object can also

trick our brains. If you stare at the center of this image, between the yellow and blue

bars, the tiny squares look like different colors, but they’re not.

If our brains could make an absolute measurement of light passing through our pupils, maybe

we wouldn’t be tricked by these illusions. But we can’t do that, our eyes aren’t cameras

or light meters or that little eyedropper tool in Photoshop.

As far as our brains are concerned, it’s not what color something is, it’s what

color something appears to be.

Which brings us back to the moon. The full moon gives enough light that

it can even cast shadows on the ground on a dark night here on Earth. But it only looks so blindingly

bright in the night sky because there’s nothing else nearby it to compare to, except

the night sky itself.

Instead of measuring the absolute

number and wavelength of photons the moon gives off, our eyes and brains compare the relative amounts

of light given off by two or more objects within our field of view.

So how bright is the moon?

Not that bright. The moon only reflects about 13% of the light that hits its surface. But

in the night sky, against the dark blackness of space, it’s the brightest

thing we can see, so our brains tell us “that’s white”.

But if we viewed the moon next to Earth, under the same illumination, it would be a very

dark gray, almost like an asphalt road. In fact, you can see this dark gray color in

photos taken on the Moon during the Apollo missions. Compared to a white spacesuit, suddenly

the moon doesn’t seem as bright, does it?

I hope you’ve enjoyed this little mind-bender, and that next time you look up at the moon,

you don’t see it in exactly the same light.

Remember, the eye and the mind work together in mysterious ways, and…

“Colors, seen by candle-light will not look the same by day.”

Stay curious.