Science Explains the Rainbows That Appear in Hummingbirds’ Wings

Christian Spencer.

Christian Spencer became well-known for his stunning photos of hummingbirds that show rainbows in their wings, it’s a specialized technique of shooting the amazing birds, one which Spencer pioneered.

Now science has taken interest in Spencer’s work; The Physics Teacher printed one of his beautiful photos on the front cover and the periodical contains an article exploring how the tiny rainbows appear in the photos.

Cover of the Physics Teacher
The December 2023 issue of The Physics Teacher.

“Nature is full of impressive physical phenomena related to electromagnetism, fluid physics, optics, and so on,” writes Professor Francisco Torcal, a lecturer of physics at the University of Zaragoza.

“Among optical phenomena, the diffraction of light can be observed in several scenarios. Diffraction occurs when light impinges on an object whose features are close to the light wavelength.

“As an example, butterfly wings’ colors are due to the diffraction of the light reflected by them.”

The Hermit and the Jacobin © Christian Spencer

“Another diffraction effect is produced when light passes through the wings of some birds, such as the hummingbird,” he continues.

“The wing is composed of very tiny hairs closely positioned parallelly, which act as a diffraction grating. This effect has been masterfully captured by the photographer Christian Spencer.

“In these photographs, we may observe the color spreading that commonly occurs when a diffraction grating is illuminated by white light, from the Sun in this case.”

Hummingbirds are the smallest of birds, and some species can zip around at over 34 miles per hour while flapping their wings at over 80 times per second, making them difficult to capture.

While studying these hard-to-photograph birds, Spencer noticed that the wings would create a prism-like effect when sunlight passed through them, causing rainbow colors to appear. He then began working to snap photos of hummingbirds passing between his lens and the Sun in order to capture these rainbows on camera.

Spencer has even inspired other photographers to take on the same challenge; PetaPixel featured Stan Maupin who waited three summers to recreate the hummingbird prism shots.

More of Spencer’s work can be found on his website and Instagram. The December 2023 edition of The Physics Teacher can be found here.

Image credits: All photos by Christian Spencer.

Update 12/1: Updated quote attribution.