 | The rainbow is always observed with the back to the sun. A line from the sun through the observer's eye leads to a point on the ground, the antisolar point, which is precisely the shadow of the head of the observer. The angle between the antisolar point and any point on the rainbow is 42 degrees, and between the antisolar point and the "secondary" rainbow is 51 degrees.
The order of colors in the inner or primary rainbow, proceeding from the center, is purple -> blue -> green -> yellow-> orange -> red, which is reversed in the secondary rainbow. Curiously the secondary rainbow has been attributed to the work of Satan, based on the widespread belief that the reversed color order is Satan's "parody of the Lord's rainbow, which had marked his covenant with Noah." *
Hence even today the secondary rainbow is sometimes referred to as the "devil's rainbow".
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* Arthur Zajonc, "Catching the Light, the Entwined History of Light and Mind", Oxford University Press, Copyright 1993, p. 169.
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