The peacock's plumage glows without pigments, thanks to the diffraction of light by its feathers.
A male peacock doing a cartwheel puts on a colourful show for us (and no doubt for his lady). Yet this shimmering plumage contains very few coloured pigments.
This miracle — this mirage — has its origins in the intimate architecture of the barbules of the peacock's feather, which bring into play a whole series of physical properties linked to the wave-like nature of light. The nanostructures in question therefore act like a network of filtering mirrors: the diffracted waves interfere with each other, and changes in hue occur depending on the intensity of the lighting or the angle from which we look at the bird.
Far from being rare, these so-called structural colours and the iridescence phenomena that often go with them are very common in nature. They are found not only in animals, birds and insects in particular, but also in certain minerals and soap bubbles.
