Show Me Some Science! Polarization of the Sky

Bees are capable of remarkable feats of orientation and navigation; they have a very strong sense of direction.

How do they do it?

One way is this: Bees are sensitive to a property of light that you and I are not, the polarization of the light. Light is an electromagnetic wave. Different waves have different wavelengths (which you sense as different colors, as do bees) and different intensities (which you sense as a difference in brightness, as do bees) and different polarizations, the direction of the electric field. You can’t sense the polarization of a light wave, but a bee can.

This is important because the blue light from the sky is polarized, and the direction of the polarization depends on the position of the sun. You can detect that the sky is blue, that the light is bright—but a bee can also tell, from looking at the sky, where the sun is, even if it can’t see the sun.

So a bee has need for a compass, as long as it can see a patch of blue sky!