The moon’s actual color is an off-white brown-gray when its dusty surface is sunlit. But Earth’s atmosphere modifies our views of the moon, altering colors and shape. Italian photographer Marcella Giulia Pace, who has captured lunar variations for 10 years, chose 48 of her images to compare in this spiral montage.
The varied colors appear when the moon is seen or photographed through stratified and irregular gas layers of Earth’s atmospheric blanket. Tiny air molecules in the layers scatter light that hits them, and their structure causes blue light to scatter more readily than red or orange. (Explore the atlas of moons.)
When, for example, Pace photographs the moon through the densest air—as it rises and as it sits just above the horizon—this phenomenon is especially intense, glowing more red or orange. Other materials in the atmosphere—water droplets, dust, wildfire smoke—also influence the path of light and affect the moon’s hue, and those colors are specific to the suspended materials themselves.
The moon’s apparent shape also is altered as the light it emits travels through the stratified air. Because the atmosphere nearest Earth’s surface is much denser than high above, the path of light traveling those varied densities will bend. The result: The light’s source appears as a squished ellipse instead of a lunar disk.
The daytime sky’s scattered blue light tints a just risen color-altered red moon (March 12, 2017).
Light passing through varied atmospheric densities is bent, changing how the moon’s shape appears (February 15, 2014).
During a total lunar eclipse, when the moon is in Earth’s shadow, bent red light falls on its surface (July 27, 2018).