A peacock feather gets iridescent color from microscopic structures rather than from pigment.

The longer version

The barbules of a peacock feather contain stacked layers of keratin and air spaced at roughly the scale of light wavelengths. Reflections from successive layers interfere, so a narrow band of wavelengths is reinforced while others are suppressed. Melanin beneath the stack absorbs stray light and sharpens the result.

Change the viewing angle and the spacing effectively changes, so the colour shifts: this is iridescence, and it means the hue lives in the geometry rather than in chemistry. Crush the feather and the colour survives, unlike a pigment, which would remain the same from every angle. Synthetic versions copy the same layered principle.

Where this entry sits

These facts explore how light behaves and how human eyes turn it into the colors we see. Along the way you meet rainbows, prisms, mirrors, shadows, lasers, and optical tricks that fool our vision every day. The full list sits on the Color and Light page, where every entry is listed in order.

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More From Color and Light

Eight more entries

Butterfly wings often shimmer with structural color produced by tiny scales instead of dyes.

Blue pigments are rare in nature, so most blue animals rely on structure instead.

Cameras capture color by filtering light through red, green, and blue sensors.

Printed images use cyan, magenta, yellow, and black ink to reproduce many colors.

Stop signals are usually red because the color stands out against most natural backgrounds.

The human eye detects color using three types of cone cells sensitive to red, green, and blue light.

Rainbows form when sunlight bends and reflects inside countless tiny water droplets in the air.

A prism splits white light into a spectrum because each wavelength bends by a different amount.

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