The Best of Demos with Positive Impact

An Online Resource for Mathematics Instructors

Home About Contact Algebra Geometry Calculus More


Moon montage.

The article MOON VIEWS IN RAINBOW HUES apppeared in the National Geographic Magazine (February, 2023, Page 32).

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 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. When, for example, Pace photographs the moon through the densest air--as it rises and it sits just above the horizon-- the phenomenon is especially intense, glowing more red and 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 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.

This article was written by LIZ KRUESI.

An online version of this article is available at MOON VIEWS. The photographer Marcella Giulia Pace has more moon views at her web site PHOTOGRAHPER.