What Color is the Moon?

Introduction

The Moon's silvery glow has graced the night sky, captivating poets, artists, and scientists alike. However, typically known for its grayish-white appearance, it can show a surprising range of colors under different conditions many might not have seen.

In this article, we'll explore the mysteries behind the Moon's various colors: in what colors can it appear, what is the science and mythology behind these colors and other interesting facts.

Before we start, it is important to understand that the Moon's actual surface color does not change, but rather our perception of it. So don't go around thinking the Moon is like a chameleon or an octopus changing its color.

Colors of the Moon

Gray Moon

First, let's look at the Moon's most familiar color: gray. On a regular night, the Moon's surface appears mostly grayish-white. This silvery color is due to the Moon's surface being mostly made of rocks and dust rich in minerals like iron and titanium. The way these elements reflect sunlight gives the Moon its usual silvery glow, visible to the naked eye.

So, in simple terms, on a regular day, we see the Moon's rock color as it is in reality—grey and white, without any added effects.

The Blue Sky: Rayleigh scattering

Before we look at some other, more unusual colors the Moon can appear in, it is important to understand the scattering of light and how it affects the Moon's and the sky's color.

In simple terms, Rayleigh scattering is when light goes in different directions as it passes through tiny particles, like air molecules or dust. The light waves bounce back and forth between these particles or scatters. This scattering makes the sky look blue during the day because blue light scatters more than other colors in the sunlight.

Sunsets also look red or orange, as sunlight has to pass through more air. Different light waves get through, scattering the blue light away and leaving the warmer colors to reach our eyes. The same scattering effect can influence the color of the Moon, causing it to appear in various hues depending on the atmospheric conditions and the presence of particles like dust or smoke.

Mysterious Blue Moon

While the term "blue Moon" traditionally refers to the second full Moon in one month, the Moon rarely appears blue. However, in certain conditions, the Moon can appear bluish when dust or smoke particles are in the air. This happens because the short wavelengths of light scatter, similar to how sunlight creates the blue sky we see during the day.

Volcanic eruptions or forest fires can cause us to see the Moon blue by throwing large amounts of smoke and dust into the air, increasing scattering.

Lunar Eclipses: The Red Moon

During a lunar eclipse, when the Earth casts its shadow over the Moon, it can become reddish-orange, earning it the nickname "Blood Moon." This captivating phenomenon also occurs because of scattered light. As sunlight passes through Earth's atmosphere, the shorter blue and green wavelengths scatter away, leaving behind the long wavelengths that make the Moon red.

What Does a Yellow Moon Mean?

We have all probably seen the Moon during the evening, looking more like a round block of cheese than its usual silvery self.

The Moon usually appears yellow when it's close to the horizon, during sunrise or sunset. This happens because the moonlight has to pass through more of the Earth's atmosphere near the horizon, and the same light scattering happens as with the red Moon. Only this time, it's not as intense as during the red Moon, so yellow light gets through, too.

Is there a Purple Moon or a Green Moon?

The concepts of a "Purple Moon" or "Green Moon" are not scientifically recognized and are more often found in cultural references, art, or fiction. So, the short answer is no; neither green nor purple Moons can occur.

In rare cases, certain atmospheric conditions or environmental factors could potentially create the illusion of a purple hue on the Moon, but it would be highly unusual.

As for a green Moon, not even some super rare conditions could cause it to look green. You could see a green Moon in photos because of some camera settings or how the light plays with the camera lenses, but it would not be a natural sight.

Moon Colors in Mythology

The Blood Moon Mythology

The mythology of the Blood Moon, particularly during lunar eclipses, differs across cultures and historical times. Many ancient cultures, like Aztecs, Mayans, and Egyptians, saw eclipses as omens of significant good and bad events.

Some cultures linked the Blood Moon to myths and legends about gods or deities, often involving themes like death, rebirth, or cosmic battles. For example, the ancient Mesopotamians believed that lunar eclipses were battles between gods and other evil forces.

Once in a Blue Moon

In some folklore traditions, people consider the Blue Moon a time of heightened spiritual energy or magical power. Some say the Blue Moon is a powerful time for rituals and spellcasting and will amplify the results.

In popular culture and modern usage, the Blue Moon has become a symbol of rarity or uniqueness. This interpretation aligns with the phrase "once in a blue Moon," which we use when something is rare and unusual.

Does Moonlight Make Everything Black and White?

The look of colors in moonlight may differ from daylight because it is simply not as bright as the Sun itself—it is just a reflection. Moonlight can create more subdued and cooler colors compared to the warmer tones of sunlight. While it may not show colors as brightly as during the day, we still see them, only less intensely.

Conclusion

1. Moon colors range from our usually-seen silvery hue to red, orange, yellow, and blue under specific conditions. It can rarely seem purplish, but it will never look green naturally.
2. During a lunar eclipse, the Moon's color can appear reddish-orange to us because Earth's atmosphere scatters blue and green light, leaving red light to shine through.
3. Our perception of the Moon's color changes depending on where it is in the sky and how its light passes through Earth's atmosphere. It might look yellow or orange near the horizon because its light travels through more of the atmosphere.
4. The Moon rarely appears blue; when it does, it is typically because of smoke or dust. These dust particles scatter shorter wavelengths of light, causing the Moon to take on a bluish tint.
5. The mythology surrounding the Blood Moon differs across cultures. It is often associated with omens or significant events. In some myths, it represents themes of death, rebirth, or cosmic battles. Folklore traditions consider the Blue Moon a time of heightened spiritual energy or magical power.
6. Moonlight doesn't turn everything black and white. Because it's not as bright as sunlight and has cooler tones, it can make things look less colorful.

References

1. Westfall, John; Sheehan, William (2014). Celestial Shadows: Eclipses, Transits, and Occultations. Springer.
2. Lee, Jane (14 April 2014). "Lunar Eclipse Myths From Around the World". National Geographic.
3. National Geographics - "A purple moon? See 48 stunning lunar hues"
4. Wikipedia - "Lunar eclipse"
5. Wikipedia  - "Blue moon"
6. NASA - "Five Things to Know about the Moon"