Iridescent describes surfaces that shimmer with shifting colors, like a rainbow on an oil slick or the gleaming wings of a beetle. When something is iridescent, its colors seem to change as you move or as light hits it from different angles. A soap bubble floating through the air displays iridescent swirls of pink, blue, and green. Hummingbird feathers appear iridescent: brilliant green from one angle, fiery orange from another.

The effect happens because of how light interacts with thin layers or microscopic structures on a surface. Unlike a painted wall that stays the same blue no matter how you look at it, an iridescent surface plays tricks with light, splitting it into different colors depending on your viewpoint.

Nature creates some of the most stunning iridescent effects: peacock feathers, butterfly wings, certain seashells, and even some fish scales. Scientists and engineers have learned to create iridescent materials too, from special paints to shimmery fabrics.