Why Does the Moon Change Colors?


The moon appears to change colors sometimes due to the scattering of light through the atmosphere. Moonlight has to pass through more atmosphere when it is on the horizon than when it is higher in the sky. By the time the moonlight is visible, all of the fragments of light on the blue end of the color spectrum have been scattered away by the air molecules, leaving only red, yellow and orange pieces of light.

The moon tends to look more reddish when it is closer to the horizon because its light must pass through heavier atmosphere. Once it has risen directly overhead, it looks more yellow or white. The same process occurs with the sun when it rises. During the day, the moon must also compete with sunlight being scattered through the atmosphere, which causes it to appear to be white.