I like your description of the distortion of refracted light from the Moon being different from the Sun or rainbow idea. I have only seen a Moonbow once in my life, and it was on a X-mas night many yrs. I was totally enthralled by that sight. Usually, Moonbows occur as a result of tiny ice crystals in the atmosphere causing this refraction instead of raindrop refraction. I'm not sure how that difference could be calculated to obtain a Speed of Light formula in that case.