If sunlight shines straight onto a peacock feather, the feather appears bright blue when viewed from 16 on either side of the incident beam of sunlight. The blue color is due to diffraction from the melanin bands in the feather barbules. Blue light with a wavelength of 472 is diffracted at 16 by these bands (this is the first-order diffraction) while other wavelengths in the sunlight are diffracted at different angles. What is the spacing of the melanin bands in the feather?