The moon appears yellow primarily because of the way its light passes through Earth's atmosphere. When the moon is low on the horizon, the light it reflects has to travel through a thicker layer of the atmosphere, which scatters shorter wavelengths of light like blue and violet. This scattering leaves the longer wavelengths, such as yellow, orange, and red, to be more visible to the observer, making the moon appear yellow or orange. This effect is especially noticeable during events like the Harvest Moon in late summer or early fall. The moon itself does not change color; it typically has a grey surface, but atmospheric conditions and particles like dust, smoke, and pollution affect how we perceive its color from Earth.
