Why does the Moon have an orange color in the Fall?

The moon is orange in the fall, because it's celebrating Halloween! Just Kidding! Actually, the moon can have an orange color at any time of the year. As a matter of fact, just last month (December 1997) in Michigan, there were a few nights when the moon looked big and orange.

Before we talk about why the moon is orange, let's learn a little bit about light. When you look at a light bulb, you see white light. But the light isn't really just white; it's a bunch of colors all mixed together. When we see a white light, we're actually seeing seven colors. Red, orange, yellow, green, blue, indigo (blue-purple), and violet (light purple), better known as Roy G. Biv. Roy G. Biv are all the colors that mix together to make white light.

We can see color whenever Roy G. Biv of white light gets split up. In order to see orange, the colors of red, yellow, green, blue, indigo and violet must be scattered away from white light by an object.

So, the reason for an orange moon is due to the scattering of light by the air in the sky. Air is full of bits of dust, water, and other tiny objects that we can't see. These bits break up the white moonlight into the separate colors of Roy G. Biv. When the moon is near the horizon, the moonlight has to pass through a lot of air. By the time the moonlight reaches our eyes, all of the colors except orange or red have been scattered away. So we see the moon as orange. When the moon is directly overhead, it has to pass through less air. The colors don't have enough bits of air to scatter away light. So we see the moon as white.

Submitted by Patrick (South Dakota, USA)
(January 9, 1998)

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