The question of whether the Moon is truly pink is common, and the answer is both no and yes, depending on the viewing location. The Moon is a celestial body that reflects sunlight, and its appearance to observers on Earth is heavily influenced by factors beyond its surface. While the Moon itself does not possess a pink hue, the combined effects of its composition and our planet’s atmosphere can make it appear that way at times.
The Moon’s Actual Surface Color
The Moon’s true color, seen without the distorting effect of Earth’s atmosphere, is not the vibrant white or yellow often imagined, but rather muted shades of gray, dark brown, and black. This coloration is determined by the composition of its surface material, known as regolith, a layer of fine dust and fragmented rock. The regolith is primarily composed of silicate minerals, including oxygen, silicon, iron, and titanium oxides.
The darker areas, known as maria (seas), are vast plains of ancient, solidified basaltic lava flows containing high concentrations of iron and titanium oxides, contributing to a grayish-black hue. In contrast, the brighter, heavily cratered highlands are made up of anorthosite, a rock richer in aluminum, giving them a lighter, chalky-white or tan-gray appearance. When viewed from space, the colors are subtle and have very low saturation, resulting in the impression of a dark, low-reflectance sphere. The Moon’s lack of an atmosphere means there are no gas molecules to scatter light, so reflected sunlight remains unaltered as it travels through space.
How Earth’s Atmosphere Changes Our View
The perception of a colored Moon—including hues of red, orange, or a pinkish tint—is an optical phenomenon caused by the Earth’s atmosphere. This effect is most pronounced when the Moon is low on the horizon during moonrise or moonset. At these times, the light reflected from the Moon must travel through a significantly greater thickness of the atmosphere to reach an observer compared to when it is directly overhead.
This extended path increases the amount of scattering, a process governed by Rayleigh scattering. Shorter wavelengths of visible light, specifically blue and violet, are scattered more effectively by the small gas molecules in the air. This scattering removes the blue end of the spectrum, allowing the longer wavelengths, which are red and orange, to pass through unimpeded.
When the remaining light reaches the viewer, the Moon appears distinctly reddish or orange. A pinkish hue is a variation of this atmospheric filtering, often influenced by the specific density of the atmosphere or the presence of additional particles. Dust, smoke, or pollution amplify this scattering effect, further intensifying the red and orange colors, which may be perceived as pink. This mechanism is the same phenomenon that causes the Sun to look red during a sunset.
The Origin of the “Pink Moon” Name
Despite atmospheric conditions that may lend a pinkish tint to the Moon, the popular term “Pink Moon” has no astronomical basis related to the Moon’s color. The name is a traditional cultural designation for the full moon that occurs in April.
This naming convention has historical roots in Native American traditions, specifically from the Algonquin tribes, who named the full moons to track seasons. The “Pink Moon” name is derived from the Phlox subulata, or moss pink, a type of pink wildflower native to the eastern United States. This plant is one of the earliest to bloom widely in the spring, and the April full moon coincided with its appearance.
The name was later popularized when The Maine Farmer’s Almanac began publishing these traditional full moon names in the 1930s. Therefore, the “Pink Moon” is a seasonal marker, not a description of the Moon’s celestial appearance, which will look white, gray, or atmospherically-filtered orange on that night.