I&#x27;m having trouble imagining how an extra cone in between red and green results rainbows and the like around the moon.  I would expect the spectrum of light forward-scattered as moonlight propagates through the atmosphere to be constant over small angular shifts.  I&#x27;d also expect the more interesting changes to be in the shorter-wavelength range, and the common tetrachromat theory (normal vision plus deuteranomaly) shouldn&#x27;t have much effect at shorter wavelengths.<p>Anyone who likes calculating scattering coefficients or who has an appropriate spectrometer should be able to check this.