Lateralman wrote:If that is correct then why can’t they be half a bubble?
It's a matter of the refraction of light through water droplets as seen by the observer that creates the arc which precludes any dome or bubble. You never find an end to a rainbow because moving also causes the rainbow to shift.
Now the OP.
Right, so it does not appear to be part of the spectrum as created via refraction but yet we do see a colour we call pink. It's an artifact of the brain trying to process two spectra from opposite ends of the visible spectrum, that's why we see it but when we see a refraction it's not there or at least that's what they suggest here
Hope is but the first step upon the road to disappointment.