Atmospheric Spectral Shift
Why does the Sun seem red near the horizon? Why does the Moon do the same? We know the Moon isn’t actually changing colour, and the Sun isn’t either. So what is happening to the light? The first thing to note about the image above is that the size of the Moon doesn’t change, showing that the well-known ‘Moon Illusion,’ where the Moon appears larger near the horizon, is just that – an illusion. The second is of course the gradual change in hue as the Moon rises. The reason for the colour shift really has nothing to do with the Moon...