The same way the sun is white when up in the sky and changes to warmer color and finally to red during sunset and sunrise, the moon also changes during moonrise and moonset.
This effect is better appreciated during the magic hours and the night, when darker the sky the more visible the color.
If it wasn’t because the sun’s light intensity is much bigger than the reflected by the moon, we could appreciate the effect also during the daylight. But, it is difficult to see nothing more than a little shade of color.
The Photographer’s Assistant calculates when color changes happens on a standard atmosphere. Particles suspended in the air such as dust, smoke, pollution, … affect the intensity, lengthening the duration of the coloration, but diminishing the intensity of the color (color dispersion).
Why does it change color?
The moon does not radiate light of its own, but reflects the light coming from the sun. That reflected light, although it has already lost much of the intensity, crosses the atmosphere and reaches us. In the same way as the sun, when lower is on the horizon, more atmosphere has to cross and, on the way, loses the frequencies of colors, blue, green, … only those belonging to red arrive.
As the elevation in the sky increases, the reflected light already has to cross less atmosphere, so the frequencies of the orange and then yellow colors can reach the observer. Finally, when the moon is high enough in the sky, it will look completely white.
Color change during the eclipses
The moon also changes color during moon eclipses. Depending on the type of eclipse, the color and intensity of the eclipse will change:
- Penumbral eclipse. The moon barely changes color, and there is only a slight darkening on the surface.
- Partial eclipse. Part of the lunar surface will be obscured by the earth, taking a color from yellow to red, depending on the magnitude of the shadow.
- Total eclipse. The lunar surface is totally in the shadow of the earth. The moon turns into an intense red.
