The color of order (and order of color)
A rainbow forms when each tiny droplet of water disperses sunlight. The pattern of light is always the same in a primary rainbow because each color is reflected at its own particular wavelength. In a primary rainbow, the colors will be in the order of red, orange, yellow, green, blue, indigo and violet. Or ROYGBIV. Red has the longest wavelength, with each color decreasing away from it. The colors seem to blend into each other because the light exits at different angles, rather than one unmoving angle. Here we see a supernumerary rainbow, an infrequent phenomenon that happens when faint rainbows are seen within the inner ring of a primary rainbow. Experts say that geometric optics does not fully explain the existence of supernumerary rainbows, which are likely created due to the varying wave nature of light.