Moon Illusion

An almost full moon taken 0.7 degrees above the horizon and an hour and a half later at 8.6 degrees.
This pair of images shows that the 'moon illusion' is an even bigger illusion that most people realise. The apparent size of rising full moon is actually smaller than when it is higher up because it has been squashed by refraction.

Different colours are refracted by slightly different amounts and this dispersion can show up near the horizon where the refraction is greatest. This produces a green rim along the top of the moon and a red rim along the bottom. (click on the image for a larger version which shows it more clearly)

Canon EOS 20D   11th July 2006
Wiltshire, England

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